Depression may affect cognitive performance among those in their 90s

Depression appeared to adversely affect cognitive performance but not cognitive change among a cohort of individuals aged 90 years or older, according to study results presented at the Alzheimer’s Association International Conference.

“Midlife depression has been associated with greater cognitive decline and risk for dementia,” Rachel A. Whitmer, PhD, of the University of California, Davis, said during a virtual presentation. “However, the role of depression in late life on cognition, particularly among those ages 90 and older, is less clear. Depression symptoms and depression can impact up to half to two-thirds of the elderly, but its prevalence among ethnically diverse oldest-old, and the role in cognitive decline in this population, is less known.”

Whitmer and colleagues analyzed data from the LifeAfter90 cohort, a racially and ethnically diverse cohort of participants aged 90 years or older that launched in 2018 to attempt to characterize cognitive and brain aging among this age group. The researchers recruited participants from an integrated health care delivery system and included those without a dementia diagnosis in their medical record at recruitment. Of 655 participants, 32% were white, 22% Asian, 22% Black, 15% Latino and 8% other/multiracial, and 38% were men. Mean participant age was 93 years.

Whitmer and colleagues assessed depression at baseline via the Global Depression Scale, with a score of four or higher indicating depression. They conducted cognitive testing every 6 months via the Spanish and English Neuropsychological Assessment Scales to evaluate cognitive domains of episodic memory, semantic memory and executive function.

Results showed 32% of participants had depression at baseline, with the highest prevalence among Latinos and those with a high school education or less. The researchers reported an association between depression and poorer semantic memory (beta = 0.17) and executive function (beta = 0.18) but not with episodic memory. Although semantic memory (beta = 0.28) and executive function (beta = 0.11) decreased over time, episodic memory did not.

“Even though semantic memory and executive function did decline over time, depression was not associated with a greater decline or a difference in decline in these two cognitive domains,” Whitmer said.