Cognitive functioning in multiple sclerosis with focus on brainstem volume

The brainstem is a vital component of the cerebro-cerebellar network underlying cognition, however it remains unclear whether brainstem volumes are associated with cognitive functioning in MS.

Investigate the relationship between brainstem volumes and cognitive impairment in MS, as assessed by the BICAMS battery (processing speed, verbal and visuospatial memory).

We analyzed data from the VOLUMS (Volumetry in MS) study, including 143 MS patients. Magnetic resonance imaging (1.5/3.0 T, 3DT1-weighted images) was used for brain volumetrics and brainstem lesion counts. Cognitive data were collected using the "Brief International Assessment of Cognition for Multiple Sclerosis" (BICAMS). Correlation and stepwise logistic regression explored associations between brain volumes and cognitive performance. In a subset of 35 patients with 3-year follow-up, longitudinal changes in brain volumes and cognition were also assessed.

Cognitive impairment (≥ 2 standard deviations below predicted scores on at least one test) was present in 30.1% of participants. No significant correlations were found between brainstem volume and cognitive scores. Hippocampus (p = .046), thalamus (p = .024), cortex (p < .001), and gray matter (p < .001) volumes were significantly lower in cognitively impaired patients. Processing speed correlated with cortex (R = .217, p = .009) and GM (R = .206, p = .013), while verbal memory correlated with hippocampus (R = .218, p = .009), cortex (R = .251, p = .003) and GM (R = .275, p = .001) volumes. Disease duration was the only significant predictor of cognitive impairment (p < .001). In the longitudinal subset, no clear evidence of progressive volumetric decline or related cognitive deterioration was observed.

While no link was found between brainstem volumes and cognitive impairment, this analysis underscores the importance of considering various brain structures in understanding cognitive impairment in MS.