Incident Stroke Associated with Accelerated and Persistent Cognitive Decline Over Six Years Post-Stroke

BACKGROUND:
Disability due to stroke is a substantial health burden and cost for families, healthcare systems, and public programs (i.e., Medicaid, Medicare). Although stroke is associated with acute cognitive decline, it is unclear whether stroke survivors acquire a faster rate of cognitive decline over the years following the event compared with the pre-stroke rate of decline. This prospective study measured changes in cognitive function among survivors of incident stroke, controlling for their pre-stroke cognitive trajectories. Investigators identified 23,572 community-dwelling individuals (45 years and older) without baseline cognitive impairment from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, who were enrolled between 2003 and 2007, and followed through March 2013. REGARDS technicians who underwent formal training and certification administered cognitive function tests by telephone. Incident strokes were adjudicated by a team of experts who reviewed medical records. Covariates included demographics, vascular risk factors (i.e., systolic blood pressure, diabetes, body mass index, alcohol intake, smoking status, and physical activity), as well as clinical risk factors (i.e., baseline cognitive scores, glomerular filtration rate, history of stroke and/or myocardial infarction, self-reported health status, and depressive symptoms).

FINDINGS:

• Incident stroke was associated with an acute decline in cognitive function and accelerated and persistent cognitive decline over a median follow-up of six years.
• Incident stroke was associated with significant acute declines in new learning and verbal memory after the event. Executive function (e.g., remembering details, managing time) also declined significantly faster post-stroke compared to pre-stroke (0.63 versus 0.31 points per year).
• Of the study cohort, 515 individuals experienced incident stroke (470 ischemic, 43 hemorrhagic), with 306 strokes among 14,632 white individuals (2.1%), and 209 strokes among 8,940 African American individuals (2.3%).
• Compared with individuals who did not experience a stroke, those who did were more likely to be older men, current smokers, diabetic, and to have less income and education.

LIMITATIONS:

• Investigators were unable to control for stroke features (i.e., location, severity), acute stroke treatments, or heart failure because these data were unavailable.
• Results are generalizable only to community-dwelling stroke survivors not requiring a proxy respondent (e.g., without aphasia).

IMPACT:

• Study results suggest that stroke survivors may warrant monitoring for increasing cognitive impairment over the years after the event. In addition, long-term cognitive dysfunction is a potential domain for evaluating acute stroke therapies.

AUTHOR/FUNDING INFORMATION:
Drs. Levine and Langa are part of HSR&D's Center for Clinical Management Research, Ann Arbor, MI.

Levine D, Galecki A, Langa K, et al. Trajectory of Cognitive Decline after Incident Stroke. JAMA. July 7, 2015;314(1):41-51.