A Mitochondrial DNA Haplogroup Defines Patterns of Five-Year Cognitive Change.

BACKGROUND:Mitochondrial DNA (mtDNA) may play a role in Alzheimer's disease (AD) and cognitive decline. A particular haplogroup of mtDNA, haplogroup J, has been observed more commonly in patients with AD than in cognitively normal controls. OBJECTIVE:We used two mtDNA haplogroups, H and J, to predict change in cognitive performance over five years. We hypothesized that haplogroup J carriers would show less cognitive resilience. METHODS:We analyzed data from 140 cognitively normal older adults who participated in the University of Kansas Alzheimer's Disease Research Center clinical cohort between 2011 and 2020. We used factor analysis to create three composite scores (verbal memory, attention, and executive function) from 11 individual cognitive tests. We performed latent growth curve modeling to describe trajectories of cognitive performance and change adjusting for age, sex, years of education, and APOE ɛ4 allele carrier status. We compared haplogroup H, the most common group, to haplogroup J, the potential risk group. RESULTS:Haplogroup J carriers had significantly lower baseline performance and slower rates of improvement on tests of verbal memory compared to haplogroup H carriers. We did not observe differences in executive function or attention. CONCLUSION:Our results reinforce the role of mtDNA in changes to cognitive function in a domain associated with risk for dementia, verbal memory, but not with other cognitive domains. Future research should investigate the distinct mechanisms by which mtDNA might affect performance on verbal memory as compared to other cognitive domains across haplogroups.