Cognitive Impairment in Transient Ischemic Attack Patients: A Systematic Review.

BACKGROUND: Although by definition a transient ischemic attack (TIA) lasts less than 24 h, many patients experience cognitive complaints beyond focal symptom resolution. However, their prevalence, causes and profile are unclear. We therefore performed a systematic review on cognitive impairment after TIA.
SUMMARY: Medline and Embase were searched for relevant studies. Risk of bias was assessed, and data synthesis was performed according to the severity of cognitive impairment. Thirteen studies were included, with considerable heterogeneity concerning methods and timing of cognitive testing. Confounding, detection bias and attrition were the main causes of a high risk of bias in several studies. The prevalence of post-TIA mild cognitive impairment ranged from 29 to 68%. Severe cognitive impairment was found in 8-22% of patients. Studies using a cognitive screening instrument and those performed shortly after TIA or several years later, reported the highest frequencies of impairment. Patients evaluated with a screening tool were substantially older than those who underwent a full neuropsychological assessment (weighted mean age difference 10.9 years). Based on limited data, the post-TIA cognitive profile showed prominent executive function deficits. Insufficient data refrained us from drawing conclusions on causality. The few studies that reported neuroimaging results found a minor correlation with cognitive impairment. KEY MESSAGES: Mild cognitive impairment is present in more than a third of the TIA patients and has a profile comparable with vascular cognitive impairment. Reported rates of post-TIA cognitive impairment are highly variable and higher frequencies are found with cognitive screening tools. Considerable heterogeneity and insufficient data limit further conclusions about potential causative factors.