Brain behavior relationships among African Americans, whites, and Hispanics - PubMed (original) (raw)
Brain behavior relationships among African Americans, whites, and Hispanics
Charles DeCarli et al. Alzheimer Dis Assoc Disord. 2008 Oct-Dec.
Abstract
There is an increasing racial and ethnic diversity within the elderly population of the United States. Although increased diversity offers unique opportunities to study novel influences on aging and dementia, some aspects of racial and ethnic research have been hampered by the lack of culturally and linguistically consistent testing protocols. Structural brain imaging is commonly used to study the biology of normal aging and cognitive impairment and may therefore serve to explore potential biologic differences of cognitive impairment among racially and ethnically diverse individuals. To test this hypothesis, we recruited a cohort of approximately 400 African American, white, and Hispanic subjects with various degrees of cognitive ability. Each subject was carefully evaluated using standardized diagnostic protocols that included clinical review of brain magnetic resonance image (MRI) to arrive at a clinical diagnosis of normal cognition, mild cognitive impairment or dementia. Each MRI was then independently quantified for measures of brain, white matter hyperintensities, and hippocampal volumes by a technician blind to subject age, sex, ethnicity, race, and diagnostic category. The appearance of infarction on MRI was also rated by examining neurologists. Regression analyses were used to assess associations with various MRI measures across clinical diagnostic categories in relation to racial and ethnic differences. Hispanic subjects were, on average, significantly younger and had less years of education than African Americans or whites. Whites with dementia were significantly older than both African American and Hispanic dementia patients. Highly significant differences in MRI measures were associated with clinical diagnoses for the group as a whole after adjusting for the effects of age, sex, education, race, and ethnicity. Subsequent independent analyses by racial and ethnic status revealed consistent relationships between diagnostic category and MRI measures. Clinical diagnoses were associated with consistent differences in brain structure among a group of racially and ethnically diverse individuals. We believe these results help to validate current diagnostic assessment of individuals across a broad range of racial, ethnic, linguistic, and educational backgrounds. Moreover, interesting and potentially biologically relevant differences were found that might stimulate further research related to the understanding of dementia etiology within an increasingly racially and ethnically diverse population.
Figures
Figure 1
a. MMSE Scores. Graphic display of MMSE scores across cognitive syndrome stratified by race and ethnicity. b. Blessed Roth Scores. Blessed-Roth disability scores across cognitive syndrome stratified by race and ethnicity.
Figure 1
a. MMSE Scores. Graphic display of MMSE scores across cognitive syndrome stratified by race and ethnicity. b. Blessed Roth Scores. Blessed-Roth disability scores across cognitive syndrome stratified by race and ethnicity.
Figure 2
MRI Measures by Diagnosis. Graphic display illustrating brain, hippocampal and WMH measures for the entire group according to clinical syndrome. Volumes were converted to z-scores for comparison across measures. See text for details.
Figure 3
a. Brain Volume by Diagnosis. b. Hippocampal Volume by Diagnosis. c. WMH Volume by Diagnosis. Graphic display of age related differences in brain (3a), hippocampal (3b) and log WMH volumes (3c). Hispanic subjects had higher mean volumes for age for both measures, but declined with age in a manner similar to African Americans and Caucasians. Measures are presented as percentage of head size to correct for potential differences related to gender and height. Note that the log of a fraction is a negative value. Since WMH/TCV is generally less than 1%, the log of this ratio is negative. Less negative values translate to higher WMH volumes.
Figure 3
a. Brain Volume by Diagnosis. b. Hippocampal Volume by Diagnosis. c. WMH Volume by Diagnosis. Graphic display of age related differences in brain (3a), hippocampal (3b) and log WMH volumes (3c). Hispanic subjects had higher mean volumes for age for both measures, but declined with age in a manner similar to African Americans and Caucasians. Measures are presented as percentage of head size to correct for potential differences related to gender and height. Note that the log of a fraction is a negative value. Since WMH/TCV is generally less than 1%, the log of this ratio is negative. Less negative values translate to higher WMH volumes.
Figure 3
a. Brain Volume by Diagnosis. b. Hippocampal Volume by Diagnosis. c. WMH Volume by Diagnosis. Graphic display of age related differences in brain (3a), hippocampal (3b) and log WMH volumes (3c). Hispanic subjects had higher mean volumes for age for both measures, but declined with age in a manner similar to African Americans and Caucasians. Measures are presented as percentage of head size to correct for potential differences related to gender and height. Note that the log of a fraction is a negative value. Since WMH/TCV is generally less than 1%, the log of this ratio is negative. Less negative values translate to higher WMH volumes.
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