Alcohol dehydrogenase is a critical enzyme in the metabolism of alcohol. Expression of three alleles at the ADH1B locus results in enzymes that differ in turnover rate and affinity for alcohol. The ADH1B*3 allele, which appears to be unique to individuals of African descent, is associated with more rapid alcohol metabolism than the more prevalent ADH1B*1 allele. It has been previously demonstrated that the presence of at least one maternal ADH1B*3 allele confers a protective effect against alcohol teratogenicity in infants and children. This study was conducted to determine whether the presence of the ADH1B*3 allele in the mother or child continues to be protective in alcohol-exposed individuals during adolescence. 186 adolescents and 167 mothers participating in a 14-year follow-up of the Detroit Longitudinal Cohort were genotyped for ADH1B alleles. Behavioral reports were obtained from classroom teachers. Frequencies of the ADH1B*3 allele were 17.6% in the mothers and 21.0% in the adolescents, which are consistent with the 15-20% expected for African Americans. Prenatal alcohol exposure was associated with increased attention problems and externalizing behaviors in adolescents born to mothers with two ADH1B*1 alleles but not in those whose mothers had at least one ADH1B*3 allele. A similar pattern was seen in relation to the presence or absence of an ADH1B*3 allele in the adolescent, which may have reflected the presence/absence of the maternal variant. This study is the first to demonstrate that the protective effects of the maternal ADH1B*3 allele continue to be evident during adolescence. These persistent individual differences in vulnerability of offspring to the behavioral effects of fetal alcohol exposure are likely attributable to more rapid metabolism of alcohol that the ADH1B*3 variant confers on the mother, leading to a reduction of the peak blood alcohol concentration to which the fetus is exposed during each drinking episode.
fetal alcohol spectrum disorders; prenatal alcohol exposure; alcohol dehydrogenase; ADH1B*3 allele; adolescent externalizing behavior
Amyloid deposition has been implicated as the key determinant of Alzheimer’s disease (AD) pathogenesis. Interventions to antagonize amyloid accumulation and mitigate dementia are now under active investigation. We conducted a combined clinical, biochemical and neuropathological assessment of a participant in a clinical trial of the γ-secretase inhibitor, semagacestat. This patient received a daily oral dose of 140 mg of semagacestat for approximately 76 weeks. Levels of brain amyloid-β (Aβ) peptides were quantified using enzyme-linked immunosorbent assays (ELISA). Western blot/scanning densitometry was performed to reveal BACE1, presenilin1, amyloid precursor protein (APP) and its proteolysis-produced C-terminal peptides APP-CT99 and APP-CT83 as well as several γ-secretase substrates. To serve as a frame of reference, the ELISA and Western analyses were performed in parallel on samples from neuropathologically confirmed non-demented control (NDC) and AD subjects who did not receive semagacestat. Neuropathology findings confirmed a diagnosis of AD with frequent amyloid deposits and neurofibrillary tangles in most areas of the cortex and subcortical nuclei as well as cerebellar amyloid plaques. Mean levels of Tris-soluble Aβ40 and glass-distilled formic acid (GDFA)/guanidine hydrochloride (GHCl)-extractable Aβ40 in the frontal lobe and GDFA/GHCl-soluble Aβ40 in the temporal lobe were increased 4.2, 9.5 and 7.7-fold, respectively, in the semagacestat-treated subject compared to those observed in the non-treated AD group. In addition, GDFA/GHCl-extracted Aβ42 was increased 2-fold in the temporal lobe relative to non-treated AD cases. No major changes in APP, β- and γ-secretase and CT99/CT83 were observed between the semagacestat-treated subject compared to either NDC or AD cases. Furthermore, the levels of γ-secretase substrates in the semagacestat-treated subject and the reference groups were also similar. Interestingly, there were significant alterations in the levels of several γ-secretase substrates between the NDC and non-treated AD subjects. This is the first reported case study of an individual enrolled in the semagacestat clinical trial. The subject of this study remained alive for ~7 months after treatment termination, therefore it is difficult to conclude whether the outcomes observed represent a consequence of semagacestat therapy. Additional evaluations of trial participants, including several who expired during the course of treatment, may provide vital clarification regarding the impacts and aftermath of γ-secretase inhibition.
Alzheimer’s disease; semagacestat immunotherapy; Alzheimer’s clinical trial; γ-secretase; γ-secretase inhibitors; γ-secretase substrates; amyloid-β
Hippocampal sclerosis (HS) is a neuropathological finding that frequently occurs with pathologies, such as Alzheimer's disease (AD). Prevalence estimates of HS in autopsy-confirmed dementia samples have varied between 0.4% and 24.5%. However, the prevalence of HS within other pathologic groups has not been well characterized.
Utilizing a sample of 910 prospectively followed and clinicopathologically confirmed dementia cases, we determined the prevalence of HS among the sample and within specific pathologic groups. HS prevalence of the sample was compared to reported HS prevalence rates in other autopsy-confirmed dementia samples.
The age range of the sample was 43 to 106 years, with a mean of 81.49±8.45. Of the 910 cases, 505 were male and 405 were female. For the entire sample, the average educational level was 14.59±2.65years. Of the 910 individuals, 47 (5.16%) cases had HS pathology present at autopsy. Among the 561 AD cases, 26 (4.43%) had HS pathology present. The frontotemporal dementia (FTD)/Pick's group had the highest percentage of cases with HS pathology (23.08%) followed by primary progressive aphasia (PPA) (16.67%) and Parkinson's disease with dementia (PDD) (5.34%). The HS prevalence rate of this study was not significantly different from all but 2 studies.
The prevalence of HS pathology in this sample of autopsy-confirmed dementia cases was similar to other reported HS prevalence rates. This study is the first to report the presence of HS pathology in PDD cases.
hippocampal sclerosis; dementia; neuropathology; TDP-43; Alzheimer's disease; Parkinson's disease
Smoking during pregnancy is common among Inuit women from the Canadian Arctic. Yet, prenatal cigarette smoke exposure (PCSE) is seen as a major risk factor for childhood behavior problems. Recent data also suggest that co-exposure to neurotoxic environmental contaminants can exacerbate the effects of PCSE on behavior. This study examined the association between PCSE and behavior at school age in a sample of Inuit children from Nunavik, Québec, where co-exposure to environmental contaminants is also an important issue. Interactions with lead (Pb) and mercury (Hg), two contaminants associated with behavioral problems, were also explored.
Participants were 271 children (mean age = 11.3 years) involved in a prospective birth-cohort study. PCSE was assessed through maternal recall. Assessment of child behavior was obtained from the child’s classroom teacher on the Teacher Report Form (TRF) and the Disruptive Behavior Disorders Rating Scale (DBD). Exposure to contaminants was assessed from umbilical cord and child blood samples. Other confounders were documented by maternal interview.
After control for contaminants and confounders, PCSE was associated with increased externalizing behaviors and attention problems on the TRF and higher prevalence of attention deficit hyperactivity disorder (ADHD) assessed on the DBD. No interactions were found with contaminants.
This study extends the existing empirical evidence linking PCSE to behavioral problems in school-aged children by reporting these effects in a population where tobacco use is normative rather than marginal. Co-exposure to Pb and Hg do not appear to exacerbate tobacco effects, suggesting that these substances act independently.
attention deficit hyperactivity disorder; prenatal smoking; tobacco smoke; child behavior; environmental contaminants; externalizing behaviors; attention problems; Teacher Report Form
Defining the biochemical alterations that occur in the brain during “normal” aging is an important part of understanding the pathophysiology of neurodegenerative diseases and of distinguishing pathological conditions from aging-associated changes. Three groups were selected based on age and on having no evidence of neurological or significant neurodegenerative disease: 1) young adult individuals, average age 26 years (n = 9); 2) middle-aged subjects, average age 59 years (n = 5); 3) oldest-old individuals, average age 93 years (n = 6). Using ELISA and Western blotting methods, we quantified and compared the levels of several key molecules associated with neurodegenerative disease in the precuneus and posterior cingulate gyrus, two brain regions known to exhibit early imaging alterations during the course of Alzheimer’s disease. Our experiments revealed that the bioindicators of emerging brain pathology remained steady or decreased with advancing age. One exception was S100B, which significantly increased with age. Along the process of aging, neurofibrillary tangle deposition increased, even in the absence of amyloid deposition, suggesting the presence of amyloid plaques is not obligatory for their development and that limited tangle density is a part of normal aging. Our study complements a previous assessment of neuropathology in oldest-old subjects, and within the limitations of the small number of individuals involved in the present investigation, it adds valuable information to the molecular and structural heterogeneity observed along the course of aging and dementia. This work underscores the need to examine through direct observation how the processes of amyloid deposition unfold or change prior to the earliest phases of dementia emergence.
Day and colleagues have presented the first data showing that the behavioral effects of low to moderate prenatal alcohol exposure seen in childhood and adolescence persist into adulthood. Using the Achenbach Adult Self Report, they found dose-dependent effects of prenatal exposure on Internalizing, Externalizing, and Attention problems that persist in young adults and, thus, appear to be permanent. To date, few studies have attempted to identify thresholds at which prenatal alcohol exposure is harmful, although the animal literature suggests that even 1–2 binge episodes can result in adverse effects in the offspring. Four prospective longitudinal studies have reported adverse effects at what can be characterized as moderate exposure levels based on NIAAA criteria, but moderate drinking women often concentrate their alcohol use on 1–2 days per week, thereby engaging in binge drinking. In this study binge drinking was not a strong predictor of adverse outcome when average daily dose was held constant, a conclusion that the authors note runs “counter to studies that have reported that binge drinking has a greater effect.” This inconsistency may be due to the difficulty of allocating variance that is shared (overlapping) between average daily dose and binge drinking (i.e., dose/occasion). Data from laboratory animal studies, in which dosage can be manipulated experimentally, demonstrate that a higher dose per occasion, the key feature of binge drinking, leads to more severe adverse effects. Day et al.’s findings of adverse effects at low levels of exposure provides clear evidence that there is no safe level of drinking during pregnancy and that, even at low levels, drinking results in irreversible behavioral impairment. On the other hand, given the evidence from the animal and most human studies, it is important for all women who drink during pregnancy, even at light to moderate levels, to recognize that minimizing their intake per occasion and refraining from binge drinking can reduce risk to the fetus.
light to moderate prenatal alcohol exposure; fetal alcohol spectrum disorders; binge drinking; adult behavior; prospective longitudinal studies; internalizing and externalizing behavior; attention
Dementia pugilistica (DP), a suite of neuropathological and cognitive function declines after chronic traumatic brain injury (TBI), is present in approximately 20% of retired boxers. Epidemiological studies indicate TBI is a risk factor for neurodegenerative disorders including Alzheimer disease (AD) and Parkinson disease (PD). Some biochemical alterations observed in AD and PD may be recapitulated in DP and other TBI persons. In this report, we investigate long-term biochemical changes in the brains of former boxers with neuropathologically confirmed DP. Our experiments revealed biochemical and cellular alterations in DP that are complementary to and extend information already provided by histological methods. ELISA and one-dimensional and two dimensional Western blot techniques revealed differential expression of select molecules between three patients with DP and three age-matched non-demented control (NDC) persons without a history of TBI. Structural changes such as disturbances in the expression and processing of glial fibrillary acidic protein, tau, and α-synuclein were evident. The levels of the Aβ–degrading enzyme neprilysin were reduced in the patients with DP. Amyloid-β levels were elevated in the DP participant with the concomitant diagnosis of AD. In addition, the levels of brain-derived neurotrophic factor and the axonal transport proteins kinesin and dynein were substantially decreased in DP relative to NDC participants. Traumatic brain injury is a risk factor for dementia development, and our findings are consistent with permanent structural and functional damage in the cerebral cortex and white matter of boxers. Understanding the precise threshold of damage needed for the induction of pathology in DP and TBI is vital.
adult brain injury; axonal injury; immunoblots; neurodegenerative disorders; traumatic brain injury
To date there is no validated peripheral biomarker to assist with the clinical diagnosis of Alzheimer’s disease (AD). Platelet proteins have been studied as AD biomarkers with relative success. In the present study we investigated whether platelet BACE1 levels differ between AD and cognitively normal (CN) control patients. Using a newly developed ELISA method, we found that BACE1 levels were significantly lower in AD compare to CN subjects. These data were supported by the observation that several BACE1 isoforms, identified by Western blotting, were also lower in AD platelets. This proof-of-concept study provides evidence for testing platelet BACE1 levels as a peripheral AD biomarker using a novel, sensitive and inexpensive method.
Alzheimer’s disease; BACE1; Biomarker; Peripheral; Platelets
Several studies have reported negative associations of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB) and mercury (Hg) with duration of gestation and foetal growth in fish eating populations. Docosahexaenoic acid (DHA) from fish, seafood and marine mammal intake has been reported to be positively related with pregnancy duration and foetal growth. So far, it remains unclear, however, if the associations of environmental contaminants (ECs) with growth are direct or mediated through their relation with the duration of gestation and the degree to which DHA intake during pregnancy attenuates the negative association of ECs with fetal growth.
To investigate direct and indirect associations of in utero exposure to ECs with foetal growth and pregnancy duration while taking into account the possible positive effects of DHA.
Pregnant Inuit women (N = 248) from Arctic Quebec were recruited and cord blood samples were analyzed for PCBs, HCB, Hg and DHA. Anthropometric measurements were assessed at birth. Path models were used to evaluate direct and indirect associations.
Cord concentrations of PCB 153, HCB and Hg were significantly associated with shorter duration of pregnancy (β varying from −0.17 to −0.20, p < 0.05). Path models indicated that the associations of PCBs, HCB and Hg with reduced foetal growth (β varying from −0.09 to −0.13, p < 0.05) were mediated through their relations with shorter gestation duration. Cord DHA was indirectly related to greater growth parameters (β varying from 0.17 to 0.20, p < 0.05) through its positive association with gestation duration.
Prenatal exposure to ECs was associated with reduced gestation duration, which is a recognized determinant of foetal growth. DHA intake during pregnancy appeared to have independent positive association with foetal growth by prolonging gestation. Whether these associations are causal remains to be elucidated.
Gestation; growth; mercury; organochlorines; polyunsaturated fatty acids; prenatal exposure
This study characterized human cerebellar activity during eyeblink classical conditioning (EBC) in children and adults using functional magnetic resonance imaging (fMRI). During fMRI, participants were administered delay conditioning trials, in which the conditioned stimulus (a tone) precedes, overlaps, and coterminates with the unconditioned stimulus (a corneal airpuff). Behavioral eyeblink responses and brain activation were measured concurrently during two phases: pseudoconditioning, involving presentations of tone alone and airpuff alone, and conditioning, during which the tone and airpuff were paired. Although all participants demonstrated significant conditioning, the adults produced more conditioned responses (CRs) than the children. When brain activations during pseudoconditioning were subtracted from those elicited during conditioning, significant activity was distributed throughout the cerebellar cortex (Crus I– II, lateral lobules IV–IX, and vermis IV–VI) in all participants, suggesting multiple sites of associative learning-related plasticity. Despite their less optimal behavioral performance, the children showed greater responding in the pons, lateral lobules VIII, IX, and Crus I, and vermis VI, suggesting that they may require greater activation and/or the recruitment of supplementary structures to achieve successful conditioning. Correlation analyses relating brain activations to behavioral CRs showed a positive association of activity in cerebellar deep nuclei (including dentate, fastigial, and interposed nuclei) and vermis VI with CRs in the children. This is the first study to compare cerebellar cortical and deep nuclei activations in children versus adults during eyeblink classical conditioning.
cerebellum; development; learning; memory; neuroimaging
Classic facial characteristics of fetal alcohol syndrome (FAS) are shortened palpebral fissures, smooth philtrum, and thin upper vermillion. We aim to help pediatricians detect facial dysmorphism across the fetal alcohol spectrum, especially among nonsyndromal heavily exposed (HE) individuals without classic facial characteristics.
Of 192 Cape Coloured children recruited, 69 were born to women who reported abstaining from alcohol during pregnancy. According to multifaceted criteria, the remainder were allocated clinically to the FAS (n = 22), partial FAS (n = 26) or nonsyndromal HE (n = 75) categories. We used dense surface modeling and signature analyses of 3-dimensional facial photographs to determine agreement between clinical categorization and classifications induced from face shape alone, to visualize facial differences, and to consider predictive links between face shape and neurobehavior.
Face classification achieved significant agreement with clinical categories for discrimination of nonexposed from FAS alone (face: 0.97–1.00; profile: 0.92) or with the addition of partial FAS (face: 0.90; profile: 0.92). Visualizations of face signatures delineated dysmorphism across the fetal alcohol spectrum and in half of the nonsyndromal HE category face signature graphs detected facial characteristics consistent with prenatal alcohol exposure. This subgroup performed less well on IQ and learning tests than did nonsyndromal subjects without classic facial characteristics.
Heat maps and morphing visualizations of face signatures may help clinicians detect facial dysmorphism across the fetal alcohol spectrum. Face signature graphs show potential for identifying nonsyndromal heavily exposed children who lack the classic facial phenotype but have cognitive impairment.
facial dysmorphism; fetal alcohol spectrum disorders; fetal alcohol syndrome; dense surface modeling; signature graphs; prenatal alcohol exposure; alcohol-related neurodevelopmental disorder
Background: Polychlorinated biphenyls (PCBs), methylmercury (MeHg), and lead (Pb) are environmental contaminants known for their adverse effects on cognitive development.
Objectives: In this study we examined the effects of prenatal exposure to PCBs, MeHg, and Pb on cognitive development in a sample of Inuit infants from Arctic Québec.
Methods: Mothers were recruited at local prenatal clinics. PCBs, mercury (Hg), Pb, and two seafood nutrients—docosahexaenoic acid (DHA) and selenium (Se)—were measured in umbilical cord blood. Infants (n = 94) were assessed at 6.5 and 11 months of age on the Fagan Test of Infant Intelligence (FTII), A-not-B test, and Bayley Scales of Infant Development–2nd Edition (BSID-II).
Results: Multiple regression analyses revealed that higher prenatal PCB exposure was associated with decreased FTII novelty preference, indicating impaired visual recognition memory. Prenatal Hg was associated with poorer performance on A-not-B, which depends on working memory and is believed to be a precursor of executive function. Prenatal Pb was related to longer FTII fixation durations, indicating slower speed of information processing.
Conclusions: PCBs, MeHg, and Pb each showed specific and distinct patterns of adverse associations with the outcomes measured during infancy. By contrast, none of these exposures was associated with performance on the BSID-II, a global developmental measure. The more focused, narrow band measures of cognitive function that appeared to be sensitive to these exposures also provide early indications of long-term impairment in specific domains that would otherwise not likely be evident until school age.
Citation: Boucher O, Muckle G, Jacobson JL, Carter RC, Kaplan-Estrin M, Ayotte P, Dewailly É, Jacobson SW. 2014. Domain-specific effects of prenatal exposure to PCBs, mercury, and lead on infant cognition: results from the Environmental Contaminants and Child Development Study in Nunavik. Environ Health Perspect 122:310–316; http://dx.doi.org/10.1289/ehp.1206323
Fetal alcohol-related growth restriction persists through infancy but its impact later in life is less clear. Animal studies have demonstrated important roles for maternal nutrition in FASD, but the impact of prenatal maternal body composition has not been studied in humans. This study examined the effects of prenatal alcohol exposure on longitudinal growth from birth through young adulthood and the degree to which maternal weight and body mass index (BMI) moderate these effects.
480 mothers were recruited at their first prenatal clinic visit to over-represent moderate-to-heavy use of alcohol during pregnancy, including a 5% random sample of low-level drinkers and abstainers. They were interviewed at every prenatal visit about their alcohol consumption using a timeline follow-back approach. Their children were examined for weight, length/height, and head circumference at birth, 6.5 and 13 months, and 7.5, 14, and 19 years.
In multiple regression models with repeated measures (adjusted for confounders), prenatal alcohol exposure was associated with longitudinal reductions in weight, height, and weight-for-length/BMI that were largely determined at birth. At low-to-moderate levels of exposure, these effects were more severe in infancy than in later childhood. By contrast, effects persisted among children whose mothers drank at least monthly and among those born to women with alcohol abuse and/or dependence who had consumed ≥4 drinks/occasion. In addition, effects on weight, height, and head circumference were markedly stronger among children born to mothers with lower prepregnancy weight.
These findings confirm prior studies demonstrating alcohol-related reductions in weight, height, weight-for-height/BMI, and head circumference that persist through young adulthood. Stronger effects were seen among children born to mothers with smaller prepregnancy weight, which may have been due to attainment of higher blood alcohol concentrations in smaller mothers for a given amount of alcohol intake or to increased vulnerability in infants born to women with poorer nutrition.
fetal alcohol syndrome; prenatal alcohol exposure; intrauterine growth retardation; postnatal growth; body composition; prepregnancy weight; maternal nutrition
Many children with heavy exposure to alcohol in utero display characteristic alterations in brain size and structure. However, the long-term effects of low-to-moderate alcohol exposure on these outcomes are unknown.
Using voxel-based morphometry and region-of-interest analyses, we examined the influence of lower doses of alcohol on gray and white matter composition in a prospectively recruited, homogeneous, well-characterized cohort of alcohol-exposed (n=11, age 19.5±0.3 yr) and control (n=9, age 19.6±0.5 yr) young adults. A large proportion of the exposed individuals were born to mothers whose alcohol consumption during pregnancy was in the low-to-moderate range.
There were no differences in total brain volume or total gray or white matter volume between the exposed and control groups. However, gray matter volume was reduced in alcohol-exposed individuals in several areas previously reported to be affected by high levels of exposure, including the left cingulate gyrus, bilateral middle frontal gyri, right middle temporal gyrus, and right caudate nucleus. Notably, this gray matter loss was dose dependent, with higher exposure producing more substantial losses.
These results indicate that even at low doses, alcohol exposure during pregnancy impacts brain development and that these effects persist into young adulthood.
prenatal alcohol exposure; voxel based morphometry; fetal alcohol spectrum disorders; brain volume
Prenatal alcohol exposure has been associated with pre- and postnatal growth restriction, but little is known about the natural history of this restriction throughout childhood or the effects of prenatal alcohol on body composition.
To examine the effects of heavy prenatal alcohol exposure on longitudinal growth and body composition.
85 heavy drinking pregnant women (≥ 2 drinks/day or ≥ 4 drinks/occasion) and 63 abstaining and light-drinking controls (< 1 drink/day, no binging) were recruited at initiation of prenatal care in an urban obstetrical clinic in Cape Town, South Africa, and prospectively interviewed during pregnancy about alcohol, smoking, drug use, and demographics. Among their children, length/height, weight, and head circumference were measured at 6.5 and 12 months and at 5 and 9 years. Percent body fat was estimated at age 9 years using bioelectric impedance analysis.
In multiple regression models with repeated measures (adjusted for confounders), heavy alcohol exposure was associated with reductions in weight (0.6 SD), length/height (0.5 SD), and head circumference (0.9 cm) from 6.5 months to 9 years that were largely determined at birth. These effects were exacerbated by iron deficiency in infancy but were not modified by iron deficiency or measures of food security at 5 years. An alcohol-related postnatal delay in weight gain was seen at 12 months. Effects on head circumference were greater at age 9 than at other age points. Although heavy alcohol exposure was not associated with changes in body composition, children with fetal alcohol syndrome (FAS) and partial FAS (PFAS) had lower % body fat than heavy exposed nonsyndromal and control children.
Heavy prenatal alcohol exposure is related to prenatal growth restriction that persists through age 9 years and an additional delay in weight gain during infancy. FAS and PFAS diagnoses are associated with leaner body composition in later childhood.
fetal alcohol syndrome; intrauterine growth retardation; postnatal growth; body composition; bioelectric impedance analysis; prenatal alcohol exposure; iron deficiency; food security
Synucleinopathies are a broad class of neurodegenerative disorders characterized by the presence of intracellular protein aggregates containing α-synuclein protein. The aggregated α-synuclein protein is hyperphosphorylated on serine 129 (S129) compared to the unaggregated form of the protein. While the precise functional consequences of S129 hyperphosphorylation are still being clarified, numerous in vitro and in vivo studies suggest that S129 phosphorylation is an early event in α-synuclein dysfunction and aggregation. Identifying the kinases and phosphatases that regulate this critical phosphorylation event may ultimately prove beneficial by allowing pharmacological mitigation of synuclein dysfunction and toxicity in Parkinson’s disease and other synucleinopathies. We report here the development of a high-content, fluorescence-based assay to quantitate levels of total and S129 phosphorylated α-synuclein protein. We have applied this assay to conduct high-throughput loss-of-function screens with siRNA libraries targeting 711 known and predicted human kinases and 206 phosphatases. Specifically, knockdown of the phosphatidylinositol 3-kinase related kinase SMG1 resulted in significant increases in the expression of pS129 phosphorylated α-synuclein (p-syn). Moreover, SMG1 protein levels were significantly reduced in brain regions with high p-syn levels in both dementia with Lewy bodies (DLB) and Parkinson’s disease with dementia (PDD). These findings suggest that SMG1 may play an important role in increased α-synuclein pathology during the course of PDD, DLB, and possibly other synucleinopathies.
Alzheimer’s disease (AD) dementia impacts all facets of higher order cognitive function and is characterized by the presence of distinctive pathological lesions in the gray matter (GM). The profound alterations in GM structure and function have fostered the view that AD impacts are primarily a consequence of GM damage. However, the white matter (WM) represents about 50% of the cerebrum and this area of the brain is substantially atrophied and profoundly abnormal in both sporadic AD (SAD) and familial AD (FAD). We examined the WM biochemistry by ELISA and Western blot analyses of key proteins in 10 FAD cases harboring mutations in the presenilin genes PSEN1 and PSEN2 as well as in 4 non-demented control (NDC) individuals and 4 subjects with SAD. The molecules examined were direct substrates of PSEN1 such as Notch-1 and amyloid precursor protein (APP). In addition, apolipoproteins, axonal transport molecules, cytoskeletal and structural proteins, neurotrophic factors and synaptic proteins were examined. PSEN-FAD subjects had, on average, higher amounts of WM amyloid-beta (Aβ) peptides compared to SAD, which may play a role in the devastating dysfunction of the brain. However, the PSEN-FAD mutations we examined did not produce uniform increases in the relative proportions of Aβ42 and exhibited substantial variability in total Aβ levels. These observations suggest that neurodegeneration and dementia do not depend solely on enhanced Aβ42 levels. Our data revealed additional complexities in PSEN-FAD individuals. Some direct substrates of γ-secretase, such as Notch, N-cadherin, Erb-B4 and APP, deviated substantially from the NDC group baseline for some, but not all, mutation types. Proteins that were not direct γ-secretase substrates, but play key structural and functional roles in the WM, likewise exhibited varied concentrations in the distinct PSEN mutation backgrounds. Detailing the diverse biochemical pathology spectrum of PSEN mutations may offer valuable insights into dementia progression and the design of effective therapeutic interventions for both SAD and FAD.
Sporadic Alzheimer’s disease; familial Alzheimer’s disease; presenilin; γ-secretase; white matter; gray matter; amyloid precursor protein; amyloid-beta
The identification of individuals exposed prenatally to alcohol can be challenging, with only those having the characteristic pattern of facial features, CNS abnormality, and growth retardation receiving a clinical diagnosis of fetal alcohol syndrome (FAS).
17 anthropometric measurements were obtained at 5 and 9 years from 125 Cape Town, South African children, studied since birth. The children were divided into 3 groups: FAS or partial FAS (PFAS), heavily exposed nonsyndromal (HE), and non-alcohol exposed controls (C). Anthropometric measurements were evaluated for mean group differences. Logistic regression models were used to identify the subset of anthropometric measures that best predicted group membership. Anthropometric measurements were examined at the two ages in relation to prenatal alcohol exposure obtained prospectively from the mothers during pregnancy. Correlation of these facial measurements with key neurobehavioral outcomes including WISC-IV IQ and eyeblink conditioning was used to assess their utility as indicators of alcohol-related central nervous system impairment.
Significant group differences were found for the majority of the anthropometric measures, with means of these measures smaller in the FAS/PFAS compared with HE or C. Upper facial widths, ear length, lower facial depth, and eye widths were consistent predictors distinguishing those exposed to alcohol from those who were not. Using longitudinal data, unique measures were identified that predicted facial anomalies at one age but not the other, suggesting the face changes as the individual matures. 41% of the FAS/PFAS group met criteria for microtia at both ages. Three of the predictive anthropometric measures were negatively related to measures of prenatal alcohol consumption, and all were positively related to at least one neurobehavioral outcome.
The analysis of longitudinal data identified a common set of predictors, as well as some that are unique at each age. Prenatal alcohol exposure appears to have its primary effect on brain growth, reflected by smaller forehead widths, and may suppress neural crest migration to the branchial arches, reflected by deficits in ear length and mandibular dimensions. These results may improve diagnostic resolution and enhance our understanding of the relation between the face and the neuropsychological deficits that occur.
fetal alcohol syndrome; fetal alcohol spectrum disorders; prenatal alcohol exposure; anthropometrics; neurobehavior; facial image; 3D photography
The objective of this report is to estimate the benefits of universal meconium screening for maternal drinking during pregnancy. Fetal alcohol spectrum disorder (FASD), including its most severe manifestation fetal alcohol syndrome (FAS), is preventable and remains a public health tragedy. The incidences of FAS and FASD have been conservatively estimated to be 0.97 and 10 per 1000 births, respectively. Meconium testing has been demonstrated to be a promising at-birth method for detection of drinking during pregnancy.
The current costs of FAS and FASD, alcohol treatment programs, and meconium screening were estimated by literature review. Monetary values were converted roughly to equal dollars in 2006.
Costs of adding meconium analysis to the current newborn screening program and of treatment for the identified mothers were estimated and compared to potential averted costs that may result from identification and intervention for mothers and affected infants. Three potential maternal treatment strategies are analyzed. Depending on the treatment type, the savings may range from $6 to $97 for every $1 spent on screening and treatment.
It needs to be emphasized, however, that such screening is premature and that to be effective this screening can be implemented only if there is a societal willingness to institute prevention and intervention programs to improve both women’s and children’s health. Future research should be directed at improving detection and developing in-depth prevention and remedial intervention programs. A thorough consideration of the ethical issues involved in such a screening program is also needed.
fetal alcohol spectrum disorder; meconium; fatty acid ethyl esters; newborn screening; benefits; maternal alcohol use
Two models of vulnerability to socioenvironmental risk were examined in 337 African American children (M = 7.8 years) recruited to over-represent prenatal alcohol or cocaine exposure: the cumulative risk model predicted synergistic effects from exposure to multiple risk factors, and the fetal patterning of disease model predicted that prenatal insult will increase vulnerability to environmental risk. Four or more risks emerged as a threshold for poorer cognitive and behavioral outcome among the non-substance exposed children, whereas substance-exposed children showed greater vulnerability to lower levels of environmental risk. Cumulative risk was associated with increased delinquent and internalizing behaviors only for the substance-exposed group. Results support the cumulative risk model for non-substance exposed children and increased vulnerability to environmental risk among the substance-exposed group.
Classical eyeblink conditioning (EBC) involves contingent temporal pairing of a conditioned stimulus (e.g., tone) with an unconditioned stimulus (e.g., air puff). Impairment of EBC has been demonstrated in studies of alcohol-exposed animals and in children exposed prenatally at heavy levels.
Fetal alcohol syndrome (FAS) was diagnosed by expert dysmorphologists in a large sample of Cape Coloured, South African children. Delay EBC was examined in a new sample of 63 children at 11.3 years, and trace conditioning in 32 of the same children at 12.8 years. At each age, two sessions of 50 trials each were administered on the same day; two more sessions the next day, for children not meeting criterion for conditioning.
6 of 34 (17.6%) children born to heavy drinkers were diagnosed with FAS, 28 were heavily exposed nonsyndromal (HE), and 29 were non-exposed controls. Only 33.3% with FAS and 42.9% of HE met criterion for delay conditioning, compared with 79.3% of controls. The more difficult trace conditioning task was also highly sensitive to fetal alcohol exposure. Only 16.7% of the FAS and 21.4% of HE met criterion for trace conditioning, compared with 66.7% of controls. The magnitude of the effect of diagnostic group on trace conditioning was not greater than the effect on short delay conditioning, findings consistent with recent rat studies. Longer latency to onset and peak eyeblink CR in exposed children indicated poor timing and failure to blink in anticipation of the puff. Extended training resulted in some but not all of the children reaching criterion.
These data showing alcohol-related delay and trace conditioning deficits extend our earlier findings of impaired EBC in 5-year-olds to school-age. Alcohol-related impairment in the cerebellar circuitry required for both forms of conditioning may be sufficient to account for the deficit in both tasks. Extended training was beneficial for some exposed children. EBC provides a well-characterized model system for assessment of degree of cerebellar-related learning and memory dysfunction in fetal alcohol exposed children.
Fetal Alcohol Syndrome; Delay Eyeblink Conditioning; Trace Eyeblink Conditioning; Fetal Alcohol Spectrum Disorder; Cerebellar-Mediated Temporal Processing
Carriers of the ApoE ϵ4 allele are at a greater risk for developing Alzheimer’s disease (AD) and those who do develop AD tend to have a much greater neuropathological disease burden. Although several studies have shown significant differences in AD pathology among ϵ4 carriers and non-carriers, few have characterized these differences in terms of brain region and neuropathological score frequency.
566 pathologically-confirmed AD cases who were followed prospectively with antemortem dementia diagnoses (312 ApoE ϵ4 carriers and 254 ApoE ϵ4 non-carriers) were compared on the frequencies of neuropathological frequency scores (none, sparse, moderate, frequent) among several different brain regions (frontal, temporal, parietal, hippocampal, and entorhinal) using the CERAD scoring system. Pathology score frequencies were analyzed by carrier status (ϵ4 carrier vs. ϵ4 non-carrier) and by genotype (2/3, 3/3, 2/4, 3/4, 4/4). Both analyses investigated pathology score frequencies among different brain regions (frontal, temporal, parietal, hippocampal, and entorhinal).
ϵ4 carriers had a significantly lower age at death (p <0.001) and significantly higher Braak scores (p <0.001) than ϵ4 non-carriers. Genotype comparison revealed that plaque and tangle pathologies increased in the following pattern, 2/3<3/3<2/4<3/4<4/4, for several brain regions. When stratified by age and ApoE ϵ4 carrier status, ϵ4 carriers tended to have significantly more frequent scores across most cortical areas. However, non-carriers age 90 and older tended to have greater plaque pathology than carriers. For tangle pathology, ϵ4 carriers tended to have significantly more “frequent” scores than non-carriers, except for the hippocampal and entorhinal areas in individuals age 90 and older.
ApoE ϵ4 carriers had a significantly higher percentage of “frequent” scores for plaques and tangles when compared to ApoE ϵ4 non-carriers for several brain regions. However, ϵ4 non-carriers age 90 and older tended to have less plaque and tangle pathology in certain brain regions. These results demonstrate that AD pathology may manifest itself differently based on ApoE genotype and suggest that ApoE carriers and non-carriers may have different patterns of AD neuropathology location and density.
Background: accurately identifying individuals with cognitive impairment is difficult. Given the time constraints that many clinicians face, assessment of cognitive status is often not undertaken. The intent of this study is to determine the diagnostic accuracy of the Alzheimer's questionnaire (AQ) in identifying individuals with mild cognitive impairment (MCI) and AD.
Methods: utilising a case–control design, 300 [100 AD, 100 MCI, 100 cognitively normal (CN)] older adults between the ages of 53 and 93 from a neurology practice and a brain donation programme had the AQ administered to an informant. Diagnostic accuracy was assessed through receiver-operating characteristic analysis, which yielded sensitivity, specificity and area under the curve (AUC).
Results: the AQ demonstrated high sensitivity and specificity for detecting MCI [89.00 (81.20–94.40)]; [91.00 (83.60–65.80)] and AD [99.00 (94.60–100.00)]; [96.00 (90.10–98.90)]. AUC values also indicated high diagnostic accuracy for both MCI [0.95 (0.91–0.97)] and AD [0.99 (0.96–1.00)]. Internal consistency of the AQ was also high (Cronbach's alpha = 0.89).
Conclusion: the AQ is a valid informant-based instrument for identifying cognitive impairment, which could be easily implemented in a clinician's practice. It has high sensitivity and specificity in detecting both MCI and AD and allows clinicians to quickly and accurately assess individuals with reported cognitive problems.
mild cognitive impairment; Alzheimer's disease; cognitive screening; informant-based assessment
To investigate predictors of missing data in a longitudinal study of Alzheimer disease (AD).
The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a clinic-based, multicenter, longitudinal study with blood, CSF, PET, and MRI scans repeatedly measured in 229 participants with normal cognition (NC), 397 with mild cognitive impairment (MCI), and 193 with mild AD during 2005–2007. We used univariate and multivariable logistic regression models to examine the associations between baseline demographic/clinical features and loss of biomarker follow-ups in ADNI.
CSF studies tended to recruit and retain patients with MCI with more AD-like features, including lower levels of baseline CSF Aβ42. Depression was the major predictor for MCI dropouts, while family history of AD kept more patients with AD enrolled in PET and MRI studies. Poor cognitive performance was associated with loss of follow-up in most biomarker studies, even among NC participants. The presence of vascular risk factors seemed more critical than cognitive function for predicting dropouts in AD.
The missing data are not missing completely at random in ADNI and likely conditional on certain features in addition to cognitive function. Missing data predictors vary across biomarkers and even MCI and AD groups do not share the same missing data pattern. Understanding the missing data structure may help in the design of future longitudinal studies and clinical trials in AD.