Neuroimaging has become an integral tool to understand aging and cognitive decline. Despite this, most research has focused on non-Hispanic, white adults. A study published in Mapping human brains attempts to bridge the racial divide in the literature by examining neuroimaging in older black adults.
Neuroimaging is an important technique that can be used to understand the aging brain, cognitive decline and dementia. Despite how important this tool is, the research focused on white samples, excluding underrepresented racial and ethnic minorities. This is extremely important, as it limits generalizability and could hinder Alzheimer’s disease interventions for non-white people.
Functional connectivity and the hippocampus have been linked to cognitive decline, dementia and Alzheimer’s disease in previous research. This study seeks to expand the field of knowledge by focusing on neuroimaging for a historically underrepresented group known to be predisposed to Alzheimer’s disease.
For their study, Duke Han and colleagues used 132 older black adults who participated in longitudinal aging studies. The mean age for the study was 76 years and 81% of the participants were female. Participants with dementia were excluded. Cognition was measured by a battery of tests that measured semantic memory, episodic memory, immediate and delayed memory, working memory, perceptual speed, and visual-spatial ability. Neuroimaging was completed through MRI scans.
The results showed that, similar to previous research conducted on a white sample, functional connectivity between the hippocampus and dorsolateral prefrontal cortex is significant for cognitive decline and aging in older black participants. The stronger the measured functional connectivity, the slower the cognitive decline in participants.
“Our results suggest that functional connectivity between the hippocampus and the dorsolateral prefrontal cortex is an important mechanism underlying cognitive decline in the context of aging, similar to what has been shown in studies with mostly older white adults,” the researchers explained. .
In addition, impaired semantic memory was linked to the decline in functional connectivity of the hippocampus with the bilateral precentral gyrus. Decreased perceptual velocity was inversely related to hippocampal function connectivity with the bilateral intracalcarinic cortex and right fusiform gyrus, suggesting possible brain compensation in response to decreases in velocity associated with aging.
“Our results suggest specific functional pathways between the hippocampus and multiple brain regions that may be targets for clinical and therapeutic interventions aimed at reducing cognitive decline and delaying or preventing AD dementia in older black adults,” the researchers concluded.
This study has taken very important steps to extend neuroimaging to older black participants, a group vulnerable to Alzheimer’s disease that has been understudied. Nevertheless, there are limitations to note. One of those limitations is that the sample was highly skewed female, which may limit generalizability. In addition, health and contextual factors beyond simple demographics were not taken into account; future research might control for more confounds.
The study, “Cognitive Decline and Hippocampal Functional Connectivity in Older Black Adults,” is authored by S. Duke Han, Debra A. Fleischman, Lei Yu, Victoria Poole, Melissa Lamar, Namhee Kim, Sue E. Leurgans, David A. Bennett , Konstantinos Arfanakis and Lisa L. Barnes.