Cognitive Decline Accelerates Years After Stroke

August 5, 2015

About one-third of stroke patients have significant cognitive impairment within several months of the event, but what is their status in the long term?

Incident stroke is associated with acute decline in cognitive function as well as a decline in new learning and memory, according to the first study to monitor cognitive function in a longitudinal manner before and after stroke.

About one-third of stroke patients have significant cognitive impairment within several months of the event. In addition, silent strokes, experienced by 1 in 10 adults by their early 60s, are harbingers of both future stroke and cognitive dysfunction.

Researchers led by Deborah A. Levine, MD, MPH, of the University of Michigan, Ann Arbor, tracked the trajectories of cognitive decline before and after incident stroke in a prospective study of 23,572 participants age 45 years or older without baseline cognitive impairment.

The participants were part of the Reasons for Geographic and Racial Differences in Stroke cohort.

Over a median follow-up of 6 years, 515 participants survived incident stroke and 23,057 remained stroke free.

All participants underwent cognitive function tests administered by telephone to assess their global cognition annually. They also underwent a battery of cognitive tests administered twice a year.

The results show stroke was associated with acute decline in global cognition, new learning, and verbal memory. “Participants with stroke, compared with those without stroke, demonstrated faster declines in global cognition and executive function, but not in new learning and verbal memory, compared with pre-stroke slopes,” they wrote.

Also, cognitive impairment was significantly faster post stroke compared with pre stroke.

As an example, the researchers note that for a 70-year-old black woman who had average values at baseline, stroke at year 3 was associated with greater incident cognitive impairment. The absolute difference was 4% at year 3 and 12.4% at year 6.

The results suggest that stroke survivors should be monitored for years, they note.

In an accompanying editorial, Philip B. Gorelick, MD, MPH, and David Nyenhuis, PhD, from the Michigan State University College of Human Medicine, Grand Rapids, state that “acute cognitive decline was associated with incident stroke and accelerated and persisted over the approximately 6-year follow-up period.”

They note that a novel feature of the study was that it allowed for pre-stroke cognition to be tracked, allowing the researchers to acquire rates of cognitive change prior to incident stroke.

These results suggest that clinicians may have an opportunity to intervene immediately following stroke to prevent accelerated stroke-related cognitive decline. They support screening for cognitive impairment over the long term following stroke.

Also of note. . .

Small Brain Lesions and Incident Stroke

Very small cerebrovascular lesions may be associated with increased risks for stroke and death, according to a new cohort study.

The presence of lesions smaller than 3 mm and 3 mm or larger may result in a particularly striking risk increase, according to a study of 1884 adults aged 50 to 73 years with MRI, no prior stroke, and average follow-up of 14.5 years.

The adults were part of the Atherosclerosis Risk in Communities Study.

Compared with no lesions, stroke risk tripled with lesions smaller than 3 mm only, doubled with lesions 3 mm or larger only, and was 8-fold higher with lesions of both sizes.

Risk for stroke-related death tripled with lesions smaller than 3 mm only and was 7 times higher with lesions of both sizes.