![Illustration of brain regions studied in mental illness: ACC, amygdala, hippocampus, prefrontal cortex. [NIH]](https://sp-ao.shortpixel.ai/client/to_webp,q_glossy,ret_img,w_750,h_375/https://www.psypost.org/wp-content/uploads/2015/08/Hippocampus-prefrontal-cortex-amygdala-anterior-cingulate-cortex-by-NIMH-750x375.jpg)
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 Human Brain Mapping seeks to bridge the racial gap in the literature by exploring 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 has focused on White samples, leaving out underrepresented racial and ethnic minorities. This is extremely significant, as it limits generalizability and could impede interventions for Alzheimer’s for non-White people.
Functional connectivity and the hippocampus have been linked with cognitive decline, dementia, and Alzheimer’s in previous research. This study seeks to expand the field of knowledge by focusing on neuroimaging for a historically underrepresented group who are known to be susceptible to Alzheimer’s.
For their study, Duke Han and colleagues utilized 132 older Black adults who were participating in longitudinal aging studies. The mean age for the study was 76 years old and 81% of participants were female. Participants with dementia were excluded. Cognition was measured by a series of tests that measured semantic memory, episodic memory, immediate and delayed recall, working memory, perceptual speed, and visuospatial ability. Neuroimaging was completed through MRI scans.
Results showed that similar to previous research completed on a White sample, functional connectivity between the hippocampus and dorsolateral prefrontal cortex is significant to cognitive decline and aging in older Black participants. The stronger the functional connectivity measured, the slower the cognitive decline seen for participants.
“Our results suggest functional connectivity between the hippocampus and dorsolateral prefrontal cortex is an important mechanism underlying cognitive decline in the context of aging, similar to what has been demonstrated in studies comprised of mostly older White adults,” the researchers explained.
Additionally, decreased semantic memory ability was linked to the decline of functional connectivity of the hippocampus with the bilateral precentral gyrus. Decreased perceptual speed had an inverse relationship with function connectivity of the hippocampus with the bilateral intracalcarine cortex and the right fusiform gyrus, indicating a potential compensation of the brain in response to decline in speed associated with aging.
“Our results suggest specific functional pathways between the hippocampus and multiple brain regions that might be targets for clinical and therapeutic interventions aimed at reduction of cognitive decline and delay or prevention of AD dementia in older Black adults,” the researchers concluded.
This study took very significant steps into expanding neuroimaging to include older Black participants, a group vulnerable to Alzheimer’s that has been understudied. Despite this, there are limitations to note. One such limitation is that the sample was heavily skewed female, which can limit generalizability. Additionally, health and contextual factors beyond simple demographics were not considered; future research could control for more confounds.
The study, “Cognitive decline and hippocampal functional connectivity within older Black adults“, was 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.