Determinants of cognitive impairment in elderly myasthenia gravis patients.

The relationship between myasthenia gravis (MG) and cognitive dysfunction has been a matter of debate because of the possible association between peripheral and central nervous system (CNS) cholinergic dysfunction. The aim of this study was to evaluate cognitive function in a series of elderly MG patients in comparison to matched controls. In all, 100 consecutive MG patients aged over 60 years and 31 matched control subjects underwent an extensive neuropsychological test battery to explore multiple cognitive domains. There were no differences in cognitive performances between patients and controls. Severe MG was associated with impaired attention, constructional praxis, and frontal control. Logistic regression analysis showed that advanced age, diabetes, and thyroid dysfunction were independently associated with cognitive impairment. This study does not support the hypothesis of CNS cholinergic involvement in MG. The impairments of attention, memory, and control tasks in MG are related to general visual motor slowness and to the concomitant presence of other diseases.