Thalamic atrophy and cognitive impairment in clinically isolated syndrome and multiple sclerosis

Cognitive deficits worsen the quality of life in multiple sclerosis and may be predicted by deep gray matter atrophy, especially thalamic atrophy. This relationship has not been studied in the clinically isolated syndrome (CIS). The aims of this study were to assess cognitive deficits in patients with CIS and relapsing-remitting multiple sclerosis (RRMS) using neuropsychological testing, to search for thalamic atrophy on brain MRI, and to test for their correlations.

Forty-three patients (19 with CIS and 24 with RRMS) underwent brain MRI and neuropsychological testing involving multiple cognitive domains and the severity of depression. Thalamic volumes automatically segmented from MRI data were compared to 19 healthy controls. Correlations were sought between cognitive performance and thalamic volume.

Cognitive impairment was detected in the majority of both CIS and MS patients, most affected in executive functions, auditory memory, lexical verbal fluency, distribution of attention and psychomotor speed. Cognitive impairment and depression were not significantly correlated to disease duration. Both CIS and MS patients demonstrated thalamic atrophy compared to controls, while many cognitive deficits correlated with thalamic volume in both patient groups.

Cognitive deficits in CIS resemble those found in the later stages of MS and may be directly related to the amount of thalamic damage.