Changes in mental state and behaviour in Huntington's disease.

Changes in mental state and behaviour have been acknowledged in Huntington's disease since the original monograph in 1872 provided evidence of disinhibition and impaired social cognition. Behavioural problems can manifest before obvious motor symptoms and are frequently the most disabling part of the illness. Although pharmacological treatments are used routinely for psychiatric difficulties in Huntington's disease, the scientific evidence base for their use is somewhat sparse.