Cognitive decline before and after a first-ever stroke in Africans.

OBJECTIVES There is a knowledge gap on the impact of pre-existing cognitive decline on poststroke decline in indigenous Africans. We describe the trajectories of domain-specific cognitive and activities of daily life (ADL) functioning across the first year of stroke in Nigerians with pre-existing cognitive decline. MATERIALS AND METHODS Prospective observational study. Prestroke cognitive decline was ascertained retrospectively using the 16-item Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE). Assessments for global cognition, learning, memory, executive and ADL functioning were conducted at 3 time points using the Mini-Mental state examination (MMSE), 10-words list learning and delayed recall test (10 WDRT), Animal naming test and Barthel index, respectively. RESULTS Among 150 stroke survivors, prestroke cognitive decline was found in 25 (16.7%, 95% C.I = 11.5%-23.6%). In linear regression analyses adjusting for the effect of age, education, stroke severity and comorbid diabetes mellitus, prestroke cognitive decline predicted poor memory scores at one year [Adjusted standardized mean difference (SMD) = -0.6, 95% C.I = -1.1, -0.1, p = 0.016)]. The association of prestroke cognitive decline with poststroke poor memory was substantially mediated by age (SMD = -0.9, 95% C.I = -1.4, -0.4, p < 0.001). CONCLUSION Pre-existing cognitive decline in this sample was associated with an age-mediated poor memory function at one-year poststroke. Early institution of targeted cognitive rehabilitation in stroke survivors with pre-existing cognitive decline may reduce the neurocognitive burden of stroke in Black Africans.