The capacity of people with a 'mental disability' to make a health care decision

Background. Based on the developing clinical and legal literature, and usin g the framework adopted in draft legislation, capacity to make a valid deci sion about a clinically required blood test was investigated in three group s of people with a 'mental disability' (i.e. mental illness (chronic schizo phrenia), 'learning disability' ('mental retardation', or intellectual or d evelopmental disability), or, dementia) and a fourth, comparison group. Methods. The three 'mental disability' groups (N = 20 in the 'learning disa bility' group, N = 21 in each of the other two groups) were recruited throu gh the relevant local clinical services; and through a phlebotomy clinic fo r the 'general population' comparison group (N = 20). The decision-making t ask was progressively simplified by presenting the relevant information as separate elements and modifying the assessment of capacity so that respondi ng became gradually less dependent on expressive verbal ability. Results. Compared with the 'general population' group, capacity to make the particular decision was significantly more impaired in the 'learning disab ility' and 'dementia' groups. Importantly, however, it was not more impaire d among the 'mental illness' group. All the groups benefited as the decisio n-making task was simplified, but at different stages. In each of the 'ment al disability' groups, one participant benefited only when responding did n ot require any expensive verbal ability. Conclusions. Consistent with current views, capacity reflected an interacti on between the decisionmaker and the demands of the decision-making task. T he findings have implications for the way in which decisions about health c are interventions are sought from people with a 'mental disability'. The me thodology may be extended to assess capacity to make other legally-signific ant decisions.