Predicting risk of dementia among the elderly with major depressive disorder in remission: A prospective study

Cognitive impairment and change are a focus of research into late-life depression. The aims of this 5-year prospective study were (1) to observe cognitive status change; (2) to investigate the rate and risk ratio of dementia or cognitive decline; and (3) to examine the cognitive domain predictors for conversion to dementia within 5 years among a clinical cohort with remitted major depressive disorder (MDD).

The study cohort included 130 elderly persons with late-life remitted MDD and 100 normal controls. Comprehensive neuropsychological tests were conducted to determine cognitive domain status. Diagnoses of mild cognitive impairment (MCI) and dementia were made at baseline and at a follow-up visit at the 5-year point. In total, 98 cases and 55 normal controls completed the 5-year follow-up assessment.

Of the study cohort with late-life remitted MDD, 28.6% had MCI and 25.5% developed dementia within 5 years. Patients with late-life remitted MDD had an approximate 3 times higher risk of subsequent cognitive decline as compared with the normal controls. Information-processing speed (p = 0.009) and memory (p = 0.041) could predict subsequent progression to dementia within 5 years among patients with MDD.

This study demonstrated that compared with the general elderly population, elderly patients with depression have more significant impairment in cognitive function after 5 years. Further, we found that in depressed patients, deficits in information-processing speed and memory domains were highly suggestive of progression to dementia within 5 years.