The Piano Man: A Case Report of Anterior Thalamic Infarct with Dementia and Preserved Music Ability.

OBJECTIVE: The thalamus is the integrative hub of the brain with reciprocal connections throughout the cortex. This case report describes a right-handed 81-year-old male patient who experienced sudden onset cognitive impairment following a focal left anterior thalamic infarct. METHODS: With consent/assent, the patient was seen for a short neuropsychological assessment 6 weeks post stroke. Neuropsychological assessment included review of medical history, collateral intake, the Toronto Cognitive Assessment, Frontal Systems Behavior Scale-Family Rating Form, the Neuropsychiatric Inventory Questionnaire, and piano performance. RESULTS: The assessment revealed impaired performance on measures of orientation, memory, executive function, and language, as well as symptoms including hallucinations, apathy, and hypersomnolence, consistent with thalamic dementia. Remarkably, in this context, the patient maintained an ability to play piano and read music. CONCLUSIONS: The case has implications for understanding the complex integrative functions of the thalamus, including how profound impairment can simultaneously present with cognitive strengths that may not be captured by performance on neuropsychological testing. This case also suggests that magnetic resonance imaging may be indicated in cases presenting with vascular risk factors and sudden onset cognitive impairment, given that computed tomography may not be sensitive to small subcortical infarcts.

Brief diesel exhaust exposure acutely impairs functional brain connectivity in humans: a randomized controlled crossover study.

BACKGROUND: While it is known that exposure to traffic-related air pollution causes an enormous global toll on human health, neurobiological underpinnings therein remain elusive. The study addresses this gap in knowledge. METHODS: We performed the first controlled human exposure study using functional MRI with an efficient order-randomized double-blind crossover study of diesel exhaust (DE) and control (filtered air; FA) in 25 healthy adults (14 males, 11 females; 19-49 years old; no withdrawals). Analyses were carried out using a mixed effects model in FLAME. Z (Gaussianised T/F) statistic images were thresholded non-parametrically using clusters determined by Z > 2.3 and a (corrected) cluster significance threshold of p = 0.05. RESULTS: All 25 adults went through the exposures and functional MRI imaging were collected. Exposure to DE yielded a decrease in functional connectivity compared to exposure to FA, shown through the comparison of DE and FA in post-exposure measurement of functional connectivity. CONCLUSION: We observed short-term pollution-attributable decrements in default mode network functional connectivity. Decrements in brain connectivity causes many detrimental effects to the human body so this finding should guide policy change in air pollution exposure regulation. TRIAL REGISTRATION: University of British Columbia Clinical Research Ethics Board (# H12-03025), Vancouver Coastal Health Ethics Board (# V12-03025), and Health Canada's Research Ethics Board (# 2012-0040).

A Systematic Review of Neuroimaging Studies Comparing Individuals with Subjective Cognitive Decline to Healthy Controls.

BACKGROUND: Individuals with subjective cognitive decline (SCD) are hypothesized to be the earliest along the cognitive continuum between healthy aging and Alzheimer's disease (AD), although more research is needed on this topic. Given that treatment approaches may be most effective pre-clinically, a primary objective of emerging research is to identify biological markers of SCD using neuroimaging methods. OBJECTIVE: The current review aimed to comprehensively present the neuroimaging studies on SCD to date. METHODS: PubMed and PsycINFO databases were searched for neuroimaging studies of individuals with SCD. Quality assessments were completed using the Appraisal tool for Cross-Sectional Studies. RESULTS: In total, 62 neuroimaging studies investigating differences between participants with SCD and healthy controls were identified. Specifically, the number of studies were as follows: 36 MRI, 6 PET, 8 MRI/PET, 4 EEG, 7 MEG, and 1 SPECT. Across neuroimaging modalities, 48 of the 62 included studies revealed significant differences in brain structure and/or function between groups. CONCLUSION: Neuroimaging methods can identify differences between healthy controls and individuals with SCD. However, inconsistent results were found within and between neuroimaging modalities. Discrepancies across studies may be best accounted for by methodological differences, notably variable criteria for SCD, and differences in participant characteristics and risk factors for AD. Clinic based recruitment and cross-sectional study design were common and may bias the literature. Future neuroimaging investigations of SCD should consistently incorporate the standardized research criteria for SCD (as recommended by the SCD-Initiative), include more details of their SCD sample and their symptoms, and examine groups longitudinally.

Identification of Earlier Biomarkers for Alzheimer's Disease: A Multimodal Neuroimaging Study of Individuals with Subjective Cognitive Decline.

BACKGROUND: Individuals with subjective cognitive decline (SCD) are thought to be the earliest along the cognitive continuum between healthy aging and Alzheimer's disease (AD). OBJECTIVE: The current study used a multi-modal neuroimaging approach to examine differences in brain structure and function between individuals with SCD and healthy controls (HC). METHODS: 3T high-resolution anatomical images and resting-state functional MRI scans were retrieved for 23 individuals with SCD and 23 HC from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. RESULTS: The SCD and HC groups were not significantly different in age or education level. Voxel-based morphometry results did not show significant differences in grey matter volume between the groups. Functional MRI results revealed significantly greater functional connectivity in the default mode network in regions including the bilateral precuneus cortex, bilateral thalamus, and right hippocampal regions in individuals with SCD relative to controls. Conversely, those with SCD showed decreased functional connectivity in the bilateral frontal pole, caudate, angular gyrus, and lingual gyrus, compared to HC. CONCLUSION: Findings revealed differences in brain function but not structure between individuals with SCD and HC. Overall, this study represents a crucial step in characterizing individuals with SCD, a group recognized to be at increased risk for AD. It is imperative to identify biomarkers of AD prior to significant decline on clinical assessment, so that disease-delaying interventions may be delivered at the earliest possible time point.

White matter and its relationship with cognition in subjective cognitive decline.

INTRODUCTION: Subjective cognitive decline (SCD) is the earliest stage on the continuum toward Alzheimer's disease. This study examined (1) differences in white matter integrity between individuals with SCD and healthy control subjects and (2) how white matter integrity related to memory and executive function. METHODS: Diffusion tensor imaging and neuropsychological assessment data were retrieved from the Alzheimer's Disease Neuroimaging Initiative database for 30 individuals with SCD and 44 control subjects. RESULTS: Results revealed significantly lower white matter integrity in individuals with SCD relative to control subjects in widespread regions, including the bilateral corticospinal tracts, superior and inferior longitudinal fasciculi, fronto-occipital fasciculi, corpus callosum, forceps major and minor, hippocampi, anterior thalamic radiations, and the cerebellum. There was a widespread relationship between diffusion tensor imaging metrics and executive function in SCD, but not healthy control subjects, and no relationship with memory for either group. DISCUSSION: Relatively lower white matter integrity in SCD may be a useful early biomarker for risk of future cognitive decline. Future research should better characterize the SCD group longitudinally and in individuals at risk for Alzheimer's disease.