Capacity to make medical treatment decisions in multiple sclerosis: a potentially remediable deficit.

Ability to make decisions about medical treatment is compromised in significant numbers of people with neurological and psychiatric illness, and this incapacity frequently corresponds with compromised neuropsychological function. Although cognitive deficits occur often in people with multiple sclerosis (MS), no research has studied decisional capacity in that disease. The present investigation examined ability to understand treatment disclosures, which is a core component of decisional capacity, in 36 people with MS and 16 normal controls. MS patients with diminished neuropsychological function showed poor understanding of treatment disclosures compared to the control group, and diminished new learning and executive function correlated with poorer understanding. Nonetheless, with sufficient cuing, the MS patients with diminished neuropsychological function were able to display understanding that was equivalent to that of the control group. Implications of these results for clinical practice and medical research involving people with MS are discussed.