TIA Associated with Long-Term Cognitive Impacts

People who experience a first-time transient ischemic attack (TIA), even without visible brain injury on imaging, demonstrated accelerated long-term cognitive decline at a rate comparable to that observed after stroke. The results of a secondary data analysis of the ongoing Reasons for Geographic and Racial Differences in Stroke (REGARDS) population-based cohort study, published in JAMA Neurology, suggest that post-TIA care and management should be reevaluated to account for potential long-term cognitive impacts, according to study investigators.

The REGARDS study enrolled 30,239 English-speaking, non-Hispanic Black and White adults aged ≥45 years living in the United States between 2003 and 2007 who were assessed for baseline demographic and medical data. On an ongoing basis, participants received follow-up for biosamples and the recording of potential cerebrovascular events as adjudicated by a committee of stroke experts. Since 2006, participants received biannual assessment for cognitive outcomes including verbal learning, verbal memory, processing speed, and executive function, which were combined as a standardized cognitive composite z score.

In the secondary analysis, researchers analyzed cognitive outcomes for 16,203 participants in the REGARDS cohort, including 356 individuals with a first-time TIA (diffusion-weighted imaging [DWI]–negative), 965 individuals with first-time stroke, and 14,883 individuals in an asymptomatic control group.

Before the index event:

• The overall cognitive composite score was lower in individuals who went on to experience stroke (-.25; 95% CI, -.32 to -.17) compared with those who experienced TIA (-.05; 95% CI, -.17 to .07; P=.005) or were in the control group (0; 95% CI, -.03 to .03; P<.001).
• This finding indicates that people who experience stroke may have a preexisting cerebrovascular burden not present for those who experience TIA or for asymptomatic controls.

After the index event:

• Participants with stroke showed a significant decline in cognitive composite score (-.45; 95% CI, -.21 to -.07) compared with those with TIA (.01; 95% CI, -.10 to .12; P=.02) or asymptomatic controls (-.03; 95% CI, -.05 to -.01; P=.003)
• Participants with stroke (-.04; 95% CI, -.05 to -.03; P=.43) and TIA (-.05; 95% CI, -.06 to -.03; P=.001) had similar annual rates of cognitive decline, which were fasters than for those in the control group (-.02; 95% CI, -.02 to -.02).
• For participants with TIA, cognitive decline was driven by verbal recall and not fluency.

The authors discuss possible mechanisms underlying TIA-related cognitive decline, including unobserved vascular risk factors, GABAergic disruption, or blood brain barrier (BBB) disruption, noting the need for further investigation.