Abstract NS10: Patients with Mild and Moderate Stroke Have Frequent, Severe, and Persistent Impairment in Information Processing Speed

Abstract

Background: One year after stroke 50-70% of survivors have information processing speed (IPS) impairment. IPS is a complex, elemental cognitive function with close but separate relationships with memory, attention, executive function, reading, and writing. IPS impairment can be devastating, even without physical deficits. Hypothesis: The frequency and severity of IPS impairment in patients with acute stroke is unrelated to stroke severity. Methods: In a longitudinal study, 30 adults with acute mild (NIHSS <5) versus moderate stroke (NIHSS 5-12) were assessed for IPS and memory impairments at three time points (< 72 hours, Week 3, and Week 12). The Symbol Digit Modalities Test (SDMT) was the primary IPS instrument, scores below the norm (51-62 points) indicate impairment. Results: Using linear mixed model regression, no significant difference was noted between patients with mild and moderate stroke in frequency and severity of IPS impairment (p=0.2). All patients had baseline abnormal SDMT scores, improving 21% by Week 12 (p=.005) with one patient scoring as unimpaired (51 points). Patients with mild stroke (n=18) had baseline scores on average 53% lower than SDMT norm (mean score 24 (12), [95% CI] 6 [18, 30], Standard Error (SEM) 3) and 32% lower at Week 12 (mean 34 (11), [95% CI] 5 [29, 40], SEM 3). Patients with moderate stroke (n=12) had baseline SDMT scores 60% lower than norm (mean 21 (11), [95% CI] 6 [15, 27], SEM 3) and 39% lower by Week 12 (mean 31 (12), [95% CI] 7 [25, 38], SEM 3). Memory impairment at enrollment (<72 hours post stroke) was noted in 100% of patients with moderate stroke and 78% of patients with mild stroke; at Week 12 the frequency of memory impairment was equal in both groups (67%). Conclusion: IPS were critically impaired, in both mild and moderate stroke, with minimal spontaneous recovery at Week 12. IPS impairment is clinically significant during stroke recovery. IPS impairment should be considered in the planning of healthcare of stroke victims even with mild stroke.