PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-7 (7)
 

Clipboard (0)
None
Journals
Year of Publication
Document Types
issn:0003-99.2
1.  Effects of Growth Hormone–Releasing Hormone on Cognitive Function in Adults With Mild Cognitive Impairment and Healthy Older Adults 
Archives of neurology  2012;69(11):1420-1429.
Background
Growth hormone–releasing hormone (GHRH), growth hormone, and insulinlike growth factor 1 have potent effects on brain function, their levels decrease with advancing age, and they likely play a role in the pathogenesis of Alzheimer disease. Previously, we reported favorable cognitive effects of short-term GHRH administration in healthy older adults and provided preliminary evidence to suggest a similar benefit in adults with mild cognitive impairment (MCI).
Objective
To examine the effects of GHRH on cognitive function in healthy older adults and in adults with MCI.
Design
Randomized, double-blind, placebo-controlled trial.
Setting
Clinical Research Center, University of Washington School of Medicine in Seattle.
Participants
A total of 152 adults (66 with MCI) ranging in age from 55 to 87 years (mean age, 68 years); 137 adults (76 healthy participants and 61 participants with MCI) successfully completed the study.
Intervention
Participants self-administered daily subcutaneous injections of tesamorelin (Theratechnologies Inc), a stabilized analog of human GHRH (1 mg/d), or placebo 30 minutes before bedtime for 20 weeks. At baseline, at weeks 10 and 20 of treatment, and after a 10-week washout (week 30), blood samples were collected, and parallel versions of a cognitive battery were administered. Before and after the 20-week intervention, participants completed an oral glucose tolerance test and a dual-energy x-ray absorptiometry scan to measure body composition.
Main Outcome Measures
Primary cognitive outcomes were analyzed using analysis of variance and included 3 composites reflecting executive function, verbal memory, and visual memory. Executive function was assessed with Stroop Color-Word Interference, Task Switching, the Self-Ordered Pointing Test, and Word Fluency, verbal memory was assessed with Story Recall and the Hopkins Verbal Learning Test, and visual memory was assessed with the Visual-Spatial Learning Test and Delayed Match-to-Sample.
Results
The intent-to-treat analysis indicated a favorable effect of GHRH on cognition (P=.03), which was comparable in adults with MCI and healthy older adults. The completer analysis showed a similar pattern, with a more robust GHRH effect (P=.002). Subsequent analyses indicated a positive GHRH effect on executive function (P=.005) and a trend showing a similar treatment-related benefit in verbal memory (P=.08). Treatment with GHRH increased insulinlike growth factor 1 levels by 117% (P<.001), which remained within the physiological range, and reduced percent body fat by 7.4% (P<.001). Treatment with GHRH increased fasting insulin levels within the normal range by 35% in adults with MCI (P<.001) but not in healthy adults. Adverse events were mild and were reported by 68% of GHRH-treated adults and 36% of those who received placebo.
Conclusions
Twenty weeks of GHRH administration had favorable effects on cognition in both adults with MCI and healthy older adults. Longer-duration treatment trials are needed to further examine the therapeutic potential of GHRH administration on brain health during normal aging and “pathological aging.”
Trial Registration
clinicaltrials.gov Identifier: NCT00257712
doi:10.1001/archneurol.2012.1970
PMCID: PMC3764914  PMID: 22869065
2.  Diet Intervention and Cerebrospinal Fluid Biomarkers in Amnestic Mild Cognitive Impairment 
Archives of neurology  2011;68(6):743-752.
Objective
To compare the effects of a 4-week high–saturated fat/high–glycemic index (HIGH) diet with a low–saturated fat/low–glycemic index (LOW) diet on insulin and lipid metabolism, cerebrospinal fluid (CSF) markers of Alzheimer disease, and cognition for healthy adults and adults with amnestic mild cognitive impairment (aMCI).
Design
Randomized controlled trial.
Setting
Veterans Affairs Medical Center clinical research unit.
Participants
Forty-nine older adults (20 healthy adults with a mean [SD] age of 69.3 [7.4] years and 29 adults with aMCI with a mean [SD] age of 67.6 [6.8] years).
Intervention
Participants received the HIGH diet (fat, 45% [saturated fat, >25%]; carbohydrates, 35%–40% [glycemic index, >70]; and protein, 15%–20%) or the LOW diet (fat, 25%; [saturated fat, <7%]; carbohydrates, 55%–60% [glycemic index, <5]; and protein, 15%–20%) for 4 weeks. Cognitive tests, an oral glucose tolerance test, and lumbar puncture were conducted at baseline and during the fourth week of the diet.
Main Outcome Measures
The CSF concentrations of β-amyloid (Aβ42 and Aβ40), tau protein, insulin, F2-isoprostanes, and apolipoprotein E, plasma lipids and insulin, and measures of cognition.
Results
For the aMCI group, the LOW diet increased CSF Aβ42 concentrations, contrary to the pathologic pattern of lowered CSF Aβ42 typically observed in Alzheimer disease. The LOW diet had the opposite effect for healthy adults, ie, decreasing CSF Aβ42, whereas the HIGH diet increased CSF Aβ42. The CSF apolipoprotein E concentration was increased by the LOW diet and decreased by the HIGH diet for both groups. For the aMCI group, the CSF insulin concentration increased with the LOW diet, but the HIGH diet lowered the CSF insulin concentration for healthy adults. The HIGH diet increased and the LOW diet decreased plasma lipids, insulin, and CSF F2-isoprostane concentrations. Delayed visual memory improved for both groups after completion of 4 weeks of the LOW diet.
Conclusion
Our results suggest that diet may be a powerful environmental factor that modulates Alzheimer disease risk through its effects on central nervous system concentrations of Aβ42, lipoproteins, oxidative stress, and insulin.
doi:10.1001/archneurol.2011.125
PMCID: PMC3175115  PMID: 21670398
3.  Intranasal Insulin Therapy for Alzheimer Disease and Amnestic Mild Cognitive Impairment 
Archives of Neurology  2011;69(1):29-38.
Objective
To examine the effects of intranasal insulin administration on cognition, function, cerebral glucose metabolism, and cerebrospinal fluid biomarkers in adults with amnestic mild cognitive impairment or Alzheimer disease (AD).
Design
Randomized, double-blind, placebo-controlled trial.
Setting
Clinical research unit of a Veterans Affairs medical center.
Participants
The intent-to-treat sample consisted of 104 adults with amnestic mild cognitive impairment (n = 64) or mild to moderate AD (n = 40).
Intervention
Participants received placebo (n = 30), 20 IU of insulin (n = 36), or 40 IU of insulin (n = 38) for 4 months, administered with a nasal drug delivery device (Kurve Technology, Bothell, Washington).
Main Outcome Measures
Primary measures consisted of delayed story recall score and the Dementia Severity Rating Scale score, and secondary measures included the Alzheimer Disease’s Assessment Scale–cognitive subscale (ADAS-cog) score and the Alzheimer’s Disease Cooperative Study–activities of daily living (ADCS-ADL) scale. A subset of participants underwent lumbar puncture (n = 23) and positron emission tomography with fludeoxyglucose F 18 (n = 40) before and after treatment.
Results
Outcome measures were analyzed using repeated-measures analysis of covariance. Treatment with 20 IU of insulin improved delayed memory (P < .05), and both doses of insulin (20 and 40 IU) preserved caregiver-rated functional ability (P < .01). Both insulin doses also preserved general cognition as assessed by the ADAS-cog score for younger participants and functional abilities as assessed by the ADCS-ADL scale for adults with AD (P < .05). Cerebrospinal fluid biomarkers did not change for insulin-treated participants as a group, but, in exploratory analyses, changes in memory and function were associated with changes in the Aβ42 level and in the tau protein–to–Aβ42 ratio in cerebrospinal fluid. Placebo-assigned participants showed decreased fludeoxyglucose F 18 uptake in the parietotemporal, frontal, precuneus, and cuneus regions and insulin-minimized progression. No treatment-related severe adverse events occurred.
Conclusions
These results support longer trials of intranasal insulin therapy for patients with amnestic mild cognitive impairment and patients with AD.
doi:10.1001/archneurol.2011.233
PMCID: PMC3260944  PMID: 21911655
4.  INSULIN RESISTANCE IS ASSOCIATED WITH ALZHEIMER-LIKE REDUCTIONS IN REGIONAL CEREBRAL GLUCOSE METABOLISM FOR COGNITIVELY NORMAL ADULTS WITH PRE-DIABETES OR EARLY TYPE 2 DIABETES 
Archives of neurology  2010;68(1):51-57.
Background
Insulin resistance is a causal factor in pre-diabetes and type 2 diabetes (T2D), and also increases the risk of developing Alzheimer’s disease (AD). Reductions in cerebral glucose metabolic rate (CMRglu) as measured by fluorodeoxyglucose positron emission tomography (FDG PET) in parietotemporal, frontal, and cingulate cortex are also associated with increased AD risk, and can be observed years before dementia onset.
Objectives
We examined whether greater insulin resistance as indexed by the homeostasis model assessment (HOMA-IR) would be associated with reduced resting CMRglu in areas known to be vulnerable in AD in a sample of cognitively normal adults with newly diagnosed pre-diabetes or T2D (P-D/T2D). We also determined whether P-D/T2D adults have abnormal patterns of CMRglu during a memory encoding task.
Design
Randomized crossover design of resting and activation [F-18] FDG-PET.
Setting
University Imaging Center and VA Clinical Research Unit.
Participants
Participants included 23 older adults (mean age±SEM=74.4±1.4) with no prior diagnosis of or treatment for diabetes, but who met American Diabetes Association glycemic criteria for pre-diabetes (n=11) or diabetes (n=12) based on fasting or 2-h oral glucose tolerance test (OGTT) glucose values, and 6 adults (mean age±SEM=74.3±2.8) with normal fasting glucose and glucose tolerance. No participant met Petersen criteria for mild cognitive impairment (MCI).
Intervention
Fasting participants rested with eyes open in a dimly lit room and underwent resting and cognitive activation [F-18]FDG PET imaging on separate days, in randomized order, at 9 am. Following a 30-min transmission scan, subjects received an intravenous injection of 5 mCi [F-18]FDG, and the emission scan commenced 40 min post-injection. In the activation condition, a 35-min memory encoding task was initiated at the time of tracer injection. Subjects were instructed to remember a repeating list of 20 words that were randomly presented in series through earphones. Delayed free recall for items on the word list was assessed once the emission scan was complete.
Main Outcome Measures
HOMA-IR was calculated for each participant using fasting glucose and insulin values obtained during OGTT screening, and then correlated with CMRglu values obtained during the resting scan. Resting CMRglu values were also subtracted from CMRglu values obtained during the memory encoding/activation scan to examine task-related patterns of CMRglu.
Results
Greater insulin resistance as indexed by HOMA-IR was associated with an AD-like pattern of reduced CMRglu in frontal, temporal-parietal, and cingulate regions in adults with P-D/T2D. The relationship between CMRglu and HOMA-IR was independent of age, 2-h OGTT glucose concentration, or apolipoprotein E-ε4 allele carriage. During the memory encoding task, normal adults showed activation in right anterior and inferior prefrontal cortex, right inferior temporal cortex, and medial and posterior cingulate regions. Compared to the normal group, adults with P-D/T2D showed a different pattern during the memory encoding task, characterized by more diffuse and extensive activation, and recalled fewer items on the delayed memory test.
Conclusions
Our results suggest that insulin resistance may be a marker of AD risk that is associated with reduced CMRglu and subtle cognitive impairments at the earliest stage of disease, even before the onset of MCI.
doi:10.1001/archneurol.2010.225
PMCID: PMC3023149  PMID: 20837822
Alzheimer’s disease; FDG PET; insulin; insulin resistance; diabetes; pre-diabetes; memory
5.  Effects of Aerobic Exercise on Mild Cognitive Impairment 
Archives of neurology  2010;67(1):71-79.
Objectives
To examine the effects of aerobic exercise on cognition and other biomarkers associated with Alzheimer disease pathology for older adults with mild cognitive impairment, and assess the role of sex as a predictor of response.
Design
Six-month, randomized, controlled, clinical trial.
Setting
Veterans Affairs Puget Sound Health Care System clinical research unit.
Participants
Thirty-three adults (17 women) with amnestic mild cognitive impairment ranging in age from 55 to 85 years (mean age,70 years).
Intervention
Participants were randomized either to a high-intensity aerobic exercise or stretching control group. The aerobic group exercised under the supervision of a fitness trainer at 75% to 85% of heart rate reserve for 45 to 60 min/d, 4 d/wk for 6 months. The control group carried out supervised stretching activities according to the same schedule but maintained their heart rate at or below 50% of their heart rate reserve. Before and after the study, glucometabolic and treadmill tests were performed and fat distribution was assessed using dual-energy x-ray absorptiometry. At baseline, month 3, and month 6, blood was collected for assay and cognitive tests were administered.
Main Outcome Measures
Performance measures on Symbol-Digit Modalities, Verbal Fluency, Stroop, Trails B, Task Switching, Story Recall, and List Learning. Fasting plasma levels of insulin, cortisol, brain-derived neurotrophic factor, insulinlike growth factor-I, and β-amyloids 40 and 42.
Results
Six months of high-intensity aerobic exercise had sex-specific effects on cognition, glucose metabolism, and hypothalamic-pituitary-adrenal axis and trophic activity despite comparable gains in cardiorespiratory fitness and body fat reduction. For women, aerobic exercise improved performance on multiple tests of executive function, increased glucose disposal during the metabolic clamp, and reduced fasting plasma levels of insulin, cortisol, and brain-derived neurotrophic factor. For men, aerobic exercise increased plasma levels of insulinlike growth factor I and had a favorable effect only on Trails B performance.
Conclusions
This study provides support, using rigorous controlled methodology, for a potent nonpharma-cologic intervention that improves executive control processes for older women at high risk of cognitive decline. Moreover, our results suggest that a sex bias in cognitive response may relate to sex-based differences in glucometabolic and hypothalamic-pituitary-adrenal axis responses to aerobic exercise.
doi:10.1001/archneurol.2009.307
PMCID: PMC3056436  PMID: 20065132
6.  The Role of Metabolic Disorders in Alzheimer's Disease and Vascular Dementia: Two Roads Converged? 
Archives of neurology  2009;66(3):300-305.
In recent years, there has been a rapidly increasing number of studies focused on the relationship between dementia and metabolic disorders such as diabetes, obesity, hypertension and dyslipidemia. Etiological heterogeneity and co-morbidity pose challenges for determining relationships among metabolic disorders. The independent and interactive effects of brain vascular injury and classic pathological agents such as Aβ have also proved difficult to untangle in human patients, blurring the lines between Alzheimer's disease and vascular dementia. This review highlights recent work aimed at identifying convergent mechanisms such as insulin resistance that may underlie co-morbid metabolic disorders and thereby increase dementia risk. Identification of such convergent factors will not only provide important insights into the causes and interdependencies of late-life dementias, but will also inspire novel strategies for treating and preventing these disorders.
doi:10.1001/archneurol.2009.27
PMCID: PMC2717716  PMID: 19273747
7.  Different Patterns of Cerebral Injury in Dementia with or Without Diabetes 
Archives of neurology  2009;66(3):315-322.
Background
Diabetes mellitus (DM) increases the risk of dementia in the elderly. However the underlying mechanisms, its connection with Alzheimer's disease (AD) and vascular cognitive impairment (VCI), and effects of therapy remain unclear.
Objective
To test the hypothesis that DM promotes specific neuropathologic processes that contribute to dementia and that these processes may be suppressed by antidiabetic therapy.
Design
A comprehensive neuropathologic assessment of all cases from a community-based study of incident dementia (Adult Changes in Thought study) that underwent autopsies (n=259) and had information on DM status (n=196). Biochemical analysis was conducted on a subset of these cases with rapidly frozen brain tissue (n=57).
Participants
Autopsy cases were divided into four groups: no DM/no dementia (DM−/dementia−), DM/no dementia (DM+/dementia−), no DM/dementia (DM−/dementia+), and DM/dementia (DM+/ dementia+). Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) diagnosis of dementia was assigned through a consensus of experts following biennial cognitive and physical evaluations. Diabetes was diagnosed based on information obtained from participants’ extensive medical records.
Results
In cases without dementia (n=125), neuropathologic or biochemical endpoints did not differ significantly by DM status. However, we observed 2 patterns of injury in patients with dementia (n=71) by their DM status. Individuals without DM, but with dementia (DM−/dementia+) had greater Aβ peptide load and increased F2-isoprostanes in the cerebral cortex, while DM+/dementia+ patients had more microvascular infarcts (MVI) and an increased cortical IL-6 (interleukin 6) concentration. The number of microvascular infarcts was greater in deep cerebral structures in patients with dementia whose diabetes was treated, whereas amyloid plaque load tended to be greater for untreated diabetic patients with dementia.
Conclusions
These novel characterizations of 2 different patterns of cerebral injury in patients with dementia depending on DM status may have etiologic and therapeutic implications.
doi:10.1001/archneurol.2008.579
PMCID: PMC2766529  PMID: 19139294

Results 1-7 (7)