Cognition and Mood in the First Few Months after Stroke: Relationship to Stroke Severity and Dependency

Introduction Cognitive decline and mood disorders are two major concerns of people affected by stroke. The extent to which cognition and mood relate to or are independent of stroke severity and post-stroke dependency are unclear. We examined the associations between stroke severity, global measures of cognition, mood and dependency up to 14-weeks post-stroke in a large national study of neurocognitive complications of stroke up to two years, the Rates, Risks and Routes to Reduce Vascular Dementia (R4VaD) study. Methods R4VaD recruited patients with stroke of all subtypes and severities and collected clinical, cognitive and mood data at baseline (within six-weeks post-stroke), subacutely (6+/-2 weeks later; ie. maximum 14-weeks post-stroke) and 1 and 2 years. We measured baseline stroke severity (National Institute of Health Stroke Scale, NIHSS), pre-stroke and 14-week dependency (Modified Rankin Scale, mRS), cognition (Montreal Cognitive Assessment, MoCA; Modified Telephone Interview for Cognitive Status, TICS-m), and mood (Zung depression scale; Patient Health Questionnaire, PHQ; General Anxiety Disorder scale, GAD-7). We analysed baseline and 14-week cognition and mood using linear models with log-transformed NIHSS, adjusted for mRS, age, sex, education, hypertension, diabetes and smoking. Results We recruited 2441 participants (mean age=68.2 SD=13.5; 40% female; median NIHSS=2.0, IQR=0-4, range=0-24; median stroke onset to recruitment=6 days, IQR=3-13; median time to follow-up=6.6 weeks, IQR=6.0-7.9). Table 1 shows baseline and subacute cognition and mood scores. At baseline higher NIHSS associated with lower cognition (MoCA: β= -0.22, p<0.001; TICS-m: β= -0.19, p<0.001) and increased depressive symptoms (Zung β=0.09, p<0.01; PHQ: β=0.09, p<0.001) independent of prestroke mRS. At 6-week follow-up higher NIHSS associated with lower cognition (T-MoCA: β= -0.06, p=0.03; TICS-m: β= -0.09, p<0.01) independent of concurrent mRS. Discussion In this largest study of neurocognitive disorders after stroke, reduced cognition is associated with worse stroke severity 6-weeks post-stroke, independent of pre and post-stroke dependency. Low mood is not independent of post-stroke dependency. The extent to which these relationships remain at 1 and 2 years will be determined shortly. Improved prediction of clinical outcomes after stroke would benefit patient care; by allowing better prediction of cognitive and mood disorders, providing better prognostic information to patients.