Activation of working memory in patients at the earliest stage of multiple sclerosis--an fMRI study.

Objective: Previous fMRI studies on activation of working memory in multiple sclerosis (MS) patients presented heterogeneous results. Patients were reported to have altered brain activation patterns either in typical working memory circuits or in other brain regions even if they did not have any cognitive impairment according to the test batteries. We hypothesized that brain activation patterns in patients at a very early stage of the disease at very low EDSS-Score would not differ from healthy subjects.

Methods: We examined 13 patients at an early stage of MS matched with 13 healthy controls with a detailed psychometric test battery and an fMRI working memory paradigm.

Results: Patients and healthy controls did not differ in psychometric test batteries. In both groups those cortex areas typically involved in working memory processes like dorso-lateral prefrontal (DLPFC), ventro-lateral-prefrontal (VLPFC), fronto-medial and parietal cortex areas (Brodmann 6, 7, 8, 9, 10, 32, 40, 45, 46, 47) were equally activated.

Conclusion: In contrast to former studies we found no differences in activation patterns in the fMRI scanning measuring working memory tasks between psychometrically tested homogenous groups of patients in early stages of MS and control subjects.