Alzheimer Disease-associated Cortical Atrophy Does not Differ Between Chinese and Whites.

PURPOSE: To assess whether there are differences in Alzheimer disease (AD)-associated atrophy regions in Chinese and white patients with AD versus cognitively normal older adults, and to test whether associations between clinical severity and gray matter volume are similar or different across these ethnic groups in a cross-sectional analysis. MATERIALS AND METHODS: Chinese and white patients with AD, individuals with mild cognitive impairment, and cognitively normal controls (46 white and 48 Chinese) were clinically evaluated at an academic center within 1 year of magnetic resonance imaging acquisition. Clinical severity was assessed using the Clinical Dementia Rating Sum of Boxes and cortical atrophy was measured using voxel-based morphometry as well as Freesurfer. Chinese and white cohorts were demographically matched for age, sex, and education. RESULTS: Clinical severity by diagnosis was similar across ethnicities. Chinese and white patient groups showed similar amounts of atrophy in the regions most affected in AD after accounting for demographic variables and head size. There was no significant difference between ethnic groups when compared by atrophy and clinical severity. CONCLUSIONS: Our study suggests that Chinese and white patients with AD, when matched demographically, are clinically and neuroanatomically similar on normalized measures of cortical atrophy and clinical severity.

Identification of a rare coding variant in TREM2 in a Chinese individual with Alzheimer's disease.

Rare variation in the TREM2 gene is associated with a broad spectrum of neurodegenerative disorders including Alzheimer's disease (AD). TREM2 encodes a receptor expressed in microglia which is thought to influence neurodegeneration by sensing damage signals and regulating neuroinflammation. Many of the variants reported to be associated with AD, including the rare R47H variant, were discovered in populations of European ancestry and have not replicated in diverse populations from other genetic backgrounds. We utilized a cohort of elderly Chinese individuals diagnosed as cognitively normal, or with mild cognitive impairment or AD to identify a rare variant, A192T, present in a single patient diagnosed with AD. We characterized this variant using biochemical cell surface expression assays and found that it significantly altered cell surface expression of the TREM2 protein. Together these data provide evidence that the A192T variant in TREM2 could contribute risk for AD. This study underscores the increasingly recognized role of immune-related processes in AD and highlights the importance of including diverse populations in research to identify genetic variation that contributes risk for AD and other neurodegenerative disorders.

Apolipoprotein ε4 is associated with lower brain volume in cognitively normal Chinese but not white older adults.

Studying ethnically diverse groups is important for furthering our understanding of biological mechanisms of disease that may vary across human populations. The ε4 allele of apolipoprotein E (APOE ε4) is a well-established risk factor for Alzheimer's disease (AD), and may confer anatomic and functional effects years before clinical signs of cognitive decline are observed. The allele frequency of APOE ε4 varies both across and within populations, and the size of the effect it confers for dementia risk may be affected by other factors. Our objective was to investigate the role APOE ε4 plays in moderating brain volume in cognitively normal Chinese older adults, compared to older white Americans. We hypothesized that carrying APOE ε4 would be associated with reduced brain volume and that the magnitude of this effect would be different between ethnic groups. We performed whole brain analysis of structural MRIs from Chinese living in America (n = 41) and Shanghai (n = 30) and compared them to white Americans (n = 71). We found a significant interaction effect of carrying APOE ε4 and being Chinese. The APOE ε4xChinese interaction was associated with lower volume in bilateral cuneus and left middle frontal gyrus (Puncorrected<0.001), with suggestive findings in right entorhinal cortex and left hippocampus (Puncorrected<0.01), all regions that are associated with neurodegeneration in AD. After correction for multiple testing, the left cuneus remained significantly associated with the interaction effect (PFWE = 0.05). Our study suggests there is a differential effect of APOE ε4 on brain volume in Chinese versus white cognitively normal elderly adults. This represents a novel finding that, if verified in larger studies, has implications for how biological, environmental and/or lifestyle factors may modify APOE ε4 effects on the brain in diverse populations.

The Chinese Verbal Learning Test specifically assesses hippocampal state.

BACKGROUND: Recently, the Chinese Verbal Learning Test (ChVLT) was developed to assess episodic memory in Chinese speakers. The goal of this analysis was to determine whether memory consolidation as measured by the ChVLT was specifically associated with hippocampal volume in patients with cognitive impairment. METHODS: We administered the ChVLT to 22 Chinese-speaking patients with mild cognitive impairment and 9 patients with dementia and obtained hippocampal and cortical volumes from T1-weighted magnetic resonance imaging. RESULTS: Linear regression revealed that hippocampal volume explained 9.9% of the variance in delayed memory (P = .018) after controlling for the effects of age, education, immediate recall after the last learning trial, overall level of cognitive impairment, and volumes of other cortical regions. CONCLUSION: These results indicate that the ChVLT is specifically correlated with hippocampal volume, supporting its utility for detecting hippocampal disease and monitoring hippocampal state over time.

Depressive symptoms in Chinese-American subjects with cognitive impairment.

OBJECTIVES: To compare the prevalence of depressive symptoms and frequency of antidepressant use between a group of elderly Chinese-American subjects with and without cognitive impairment and a group of matched white subjects. A secondary aim was to examine the clinical and demographic predictors of depressive symptoms across these groups. METHODS: The study was conducted at an academic neurology subspecialty clinic. This was a case-control study with 140 Chinese-American subjects and 140 demographically and cognitively matched white subjects. In each group, there were 48 cognitively normal and 92 cognitively impaired participants (49 with mild cognitive impairment, 43 with Alzheimer disease). The proportion of individuals with significant depressive symptoms, as indicated by a Geriatric Depression Scale score ≥6 of 15, and frequency of antidepressant use were compared across groups by using χ(2) analysis. Factors predicting depressive symptoms, including racial and diagnostic group, age, gender, Mini-Mental State Examination score, level of functional impairment, education level, and medical comorbidities, were assessed by using linear regression analysis. RESULTS: Significant depressive symptoms were more common in cognitively impaired Chinese-American (35%) than cognitively impaired white (15%; χ(2)[1] = 9.4; p = 0.004) subjects. Chinese-American subjects with cognitive impairment were less likely to be receiving treatment for depression (12%) than white subjects with cognitive impairment (37%; χ(2)[1] = 15.6; p = 0.002). Racial and diagnostic group, age, level of functional impairment, Mini-Mental State Examination score, and education level were all statistically significant independent predictors of Geriatric Depression Scale score. CONCLUSIONS: Elderly Chinese-American subjects with cognitive impairment are at increased risk for unrecognized and untreated depressive symptoms compared with elderly white subjects with cognitive impairment. Education level may contribute to this risk or it may be a surrogate marker for other factors contributing to depressive symptoms in this group.

Frontotemporal dementia in eight Chinese individuals.

Frontotemporal dementia (FTD) has rarely been reported in Chinese populations. There are many potential reasons for this, including possible hesitancy on the part of patients or families to bring FTD-related symptoms to medical attention. Here, we present data on eight Chinese individuals, all of whom met criteria for the behavioral variant of FTD or the semantic variant of primary progressive aphasia. These patients presented for neurological evaluation at a relatively advanced stage. The mean MMSE score at initial presentation was 15. Behavioral symptoms were common and usually elicited during the medical history only after direct questioning. Delay in presentation was attributed to a variety of issues, including family disagreements about whether the symptoms represented a disease and lack of medical insurance. These cases illustrate that the symptoms of FTD in Chinese-Americans are similar to those in Caucasians but various factors, some potentially culturally relevant, may influence the likelihood and timing of clinical presentation for FTD, as well as other dementias. Additional study of FTD in diverse ethnic groups needs to address barriers to clinical presentation, including factors that may be culturally specific.

Recruitment of Chinese American elders into dementia research: the UCSF ADRC experience.

PURPOSE: To describe the results of efforts to recruit Asian Americans into longitudinal research on cognitive decline in aging. DESIGN AND METHODS: Recruitment strategies include clinics for assessment of cognitive impairment at the University of California, San Francisco campus and San Francisco's Chinatown, lectures to local health care providers and community members, participation in community events, and publications in mass media. RESULTS: Over 200 Chinese patients were evaluated in our outreach clinic. Many were primarily Chinese speaking with low levels of education. One hundred and twenty-five participants enrolled, and annual follow-up has been 88%. Among enrollees, 36% were recruited from our clinical service; 30% via word of mouth; and the rest from community lectures and events, flyers, and mass media. Participants who enrolled were relatively highly educated, tended to be interested in learning about their cognitive abilities, and were supportive of the goals of research. IMPLICATIONS: Despite the significant cultural and linguistic barriers, Chinese Americans can be successfully recruited into longitudinal studies of aging and cognitive impairment. Clinical services are a critical component of such an effort, and low education and other factors that may be associated with it are clear barriers to research participation.