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1.  Dementia Resulting From Traumatic Brain Injury 
Archives of neurology  2012;69(10):1245-1251.
Traumatic brain injury (TBI) is among the earliest illnesses described in human history and remains a major source of morbidity and mortality in the modern era. It is estimated that 2% of the US population lives with long-term disabilities due to a prior TBI, and incidence and prevalence rates are even higher in developing countries. One of the most feared long-term consequences of TBIs is dementia, as multiple epidemiologic studies show that experiencing a TBI in early or midlife is associated with an increased risk of dementia in late life. The best data indicate that moderate and severe TBIs increase risk of dementia between 2-and 4-fold. It is less clear whether mild TBIs such as brief concussions result in increased dementia risk, in part because mild head injuries are often not well documented and retrospective studies have recall bias. However, it has been observed for many years that multiple mild TBIs as experienced by professional boxers are associated with a high risk of chronic traumatic encephalopathy (CTE), a type of dementia with distinctive clinical and pathologic features. The recent recognition that CTE is common in retired professional football and hockey players has rekindled interest in this condition, as has the recognition that military personnel also experience high rates of mild TBIs and may have a similar syndrome. It is presently unknown whether dementia in TBI survivors is pathophysiologically similar to Alzheimer disease, CTE, or some other entity. Such information is critical for developing preventive and treatment strategies for a common cause of acquired dementia. Herein, we will review the epidemiologic data linking TBI and dementia, existing clinical and pathologic data, and will identify areas where future research is needed.
PMCID: PMC3716376  PMID: 22776913
2.  Regionally Selective Atrophy after Traumatic Axonal Injury 
Archives of neurology  2010;67(11):1336-1344.
To determine the spatial distribution of cortical and subcortical volume loss in patients with diffuse traumatic axonal injury and to assess the relationship between regional atrophy and functional outcome.
Prospective imaging study. Longitudinal changes in global and regional brain volumes were assessed using high-resolution magnetic resonance imaging (MRI)-based morphometric analysis.
Inpatient traumatic brain injury unit
Patients or Other Participants
Twenty-five patients with diffuse traumatic axonal injury and 22 age- and sex-matched controls.
Main Outcome Measure
Changes in global and regional brain volumes between initial and follow-up MRI were used to assess the spatial distribution of post-traumatic volume loss. The Glasgow Outcome Scale – Extended was the primary measure of functional outcome.
Patients underwent substantial global atrophy with mean brain parenchymal volume loss of 4.5% (95% Confidence Interval: 2.7 – 6.3%). Decreases in volume (at a false discovery rate of 0.05) were seen in several brain regions including the amygdala, hippocampus, thalamus, corpus callosum, putamen, precuneus, postcentral gyrus, paracentral lobule, and parietal and frontal cortices, while other regions such as the caudate and inferior temporal cortex were relatively resistant to atrophy. Loss of whole brain parenchymal volume was predictive of long-term disability, as was atrophy of particular brain regions including the inferior parietal cortex, pars orbitalis, pericalcarine cortex, and supramarginal gyrus.
Traumatic axonal injury leads to substantial post-traumatic atrophy that is regionally selective rather than diffuse, and volume loss in certain regions may have prognostic value for functional recovery.
PMCID: PMC3465162  PMID: 20625067
3.  Elevated Serum Pesticide Levels and Risk of Parkinson Disease 
Archives of Neurology  2009;66(7):870-875.
Exposure to pesticides has been reported to increase the risk of Parkinson disease (PD), but identification of the specific pesticides is lacking. Three studies have found elevated levels of organochlorine pesticides in postmortem PD brains.
To determine whether elevated levels of organochlorine pesticides are present in the serum of patients with PD.
Case-control study.
An academic medical center.
Fifty patients with PD, 43 controls, and 20 patients with Alzheimer disease.
Main Outcome Measures
Levels of 16 organochlorine pesticides in serum samples.
β-Hexachlorocyclohexane (β-HCH) was more often detectable in patients with PD (76%) compared with controls (40%) and patients with Alzheimer disease (30%). The median level of β-HCH was higher in patients with PD compared with controls and patients with Alzheimer disease. There were no marked differences in detection between controls and patients with PD concerning any of the other 15 organochlorine pesticides. Finally, we observed a significant odds ratio for the presence of β-HCH in serum to predict a diagnosis of PD vs control (odds ratio, 4.39; 95% confidence interval, 1.67–11.6) and PD vs Alzheimer disease (odds ratio, 5.20), which provides further evidence for the apparent association between serum β-HCH and PD.
These data suggest that β-HCH is associated with a diagnosis of PD. Further research is warranted regarding the potential role of β-HCH as a etiologic agent for some cases of PD.
PMCID: PMC3383784  PMID: 19597089
4.  Temporoparietal hypometabolism is common in FTLD and is associated with imaging diagnostic errors 
Archives of neurology  2010;68(3):329-337.
To evaluate the cause of diagnostic errors in the visual interpretation of positron emission tomography scans with 18F-fluorodeoxyglucose (FDG-PET) in patients with frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD).
Twelve trained raters unaware of clinical and autopsy information independently reviewed FDG-PET scans and provided their diagnostic impression and confidence of either FTLD or AD. Six of these raters also recorded whether metabolism appeared normal or abnormal in 5 predefined brain regions in each hemisphere – frontal cortex, anterior cingulate cortex, anterior temporal cortex, temporoparietal cortex and posterior cingulate cortex. Results were compared to neuropathological diagnoses.
Academic medical centers
45 patients with pathologically confirmed FTLD (n=14) or AD (n=31)
Raters had a high degree of diagnostic accuracy in the interpretation of FDG-PET scans; however, raters consistently found some scans more difficult to interpret than others. Unanimity of diagnosis among the raters was more frequent in patients with AD (27/31, 87%) than in patients with FTLD (7/14, 50%) (p = 0.02). Disagreements in interpretation of scans in patients with FTLD largely occurred when there was temporoparietal hypometabolism, which was present in 7 of the 14 FTLD scans and 6 of the 7 lacking unanimity. Hypometabolism of anterior cingulate and anterior temporal regions had higher specificities and positive likelihood ratios for FTLD than temporoparietal hypometabolism had for AD.
Temporoparietal hypometabolism in FTLD is common and may cause inaccurate interpretation of FDG-PET scans. An interpretation paradigm that focuses on the absence of hypometabolism in regions typically affected in AD before considering FTLD is likely to misclassify a significant portion of FTLD scans. Anterior cingulate and/or anterior temporal hypometabolism indicates a high likelihood of FTLD, even when temporoparietal hypometabolism is present. Ultimately, the accurate interpretation of FDG-PET scans in patients with dementia cannot rest on the presence or absence of a single region of hypometabolism, but must take into account the relative hypometabolism of all brain regions.
PMCID: PMC3058918  PMID: 21059987
5.  A Serum Protein-Based Algorithm for the Detection of Alzheimer's Disease 
Archives of neurology  2010;67(9):1077-1081.
Alzheimer's disease (AD) is the most common form of age-related dementia and one of the most serious health problems in the industrialized world. Biomarker approaches to diagnostics would be more time and cost effective and may also be useful for identifying endophenotypes within AD patient populations.
We analyzed serum protein-based multiplex biomarker data from 197 patients diagnosed with AD and 203 controls from a longitudinal study of Alzheimer's disease being conducted by the Texas Alzheimer's Research Consortium to develop an algorithm that separates AD from controls. The total sample was randomized equally into training and test sets and random forest methods were applied to the training set to create a biomarker risk score.
The biomarker risk score had a sensitivity and specificity of 0.80 and 0.91, respectively and an AUC of 0.91 in detecting AD. When age, gender, education, and APOE status were added to the algorithm, the sensitivity, specificity, and AUC were 0.94, 0.84, and 0.95, respectively.
These initial data suggest that serum protein-based biomarkers can be combined with clinical information to accurately classify AD. Of note, a disproportionate number of inflammatory and vascular markers were weighted most heavily in analyses. Additionally, these markers consistently distinguished cases from controls in SAM, logistic regression and Wilcoxon analyses, suggesting the existence of an inflammatory-related endophenotype of AD that may provide targeted therapeutic opportunities for this subset of patients.
PMCID: PMC3069805  PMID: 20837851
6.  Deficits in Functional Connectivity of Hippocampal and Frontal Lobe Circuits after Traumatic Axonal Injury 
Archives of neurology  2011;68(1):74-84.
To examine the functional connectivity (fc) of hippocampal and selected frontal lobe circuits among patients with traumatic axonal injury (TAI).
Echo-planar and high-resolution T1-weighted images were acquired using 3 Tesla scanners. Regions of interest (ROI) were drawn bilaterally for the hippocampus, anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex (DLPFC), and were used to extract time series data. BOLD data from each ROI were used as reference functions for correlating with all other brain voxels. Interhermispheric fc was assessed for each participant by correlating homologous regions using a Pearson correlation coefficient. Patient functional and neurocognitive outcomes were assessed approximately 6 months post-injury.
Patients were recruited within days of their injury while in an inpatient traumatic brain injury unit. Imaging and neurocognitive assessments were conducted in an outpatient research facility.
25 consecutive patients with brain injuries consistent with TAI and acute subcortical white matter abnormalities were studied. Sixteen healthy volunteers of similar age and gender were recruited.
Main Outcome Measures
Interhemispheric fc for each ROI was compared between patients and controls. Spatial patterns of fc were examined for each of the three ROIs. Connectivity measures were examined for associations with functional and neurocognitive outcomes.
Patients showed significantly lower interhemispheric fc for the hippocampus and ACC. Healthy controls demonstrate stronger and more focused fc for hippocampi and ACC, and a more focused recruitment of the default mode network for the DLPFC ROI. The interhemispheric fc for the hippocampus was correlated to delayed recall of verbal information.
Our findings suggest that traumatic axonal injury impacts interhemispheric neural activity, as patients with TAI show disrupted interhemipsheric fc. These results suggest more careful investigation of interhemisheric connectivity is warranted, as it demonstrated a modest association with outcome in chronic TBI.
PMCID: PMC3100186  PMID: 21220676

Results 1-6 (6)