Objective: To investigate behavioural problems in Huntington's disease (HD).
Method: In 152 HD mutation carriers and a control group of 56 noncarriers at initial 50% risk, the Dutch version of the Problem Behaviours Assessment (PBA) was administered. Mutation carriers were divided into three groups according to the motor section of the Unified Huntington's Disease Rating Scale (UHDRS): pre-(motor) symptomatic, early and advanced symptomatic subjects. The factor structure and interrater reliability of the PBA were investigated.
Results: The clinically relevant interrater reliability of the PBA was 0.82 for severity scores and 0.73 for frequency scores. The PBA showed a three-factor solution: apathy, depression and irritability. Mutation carriers, including presymptomatic subjects, portrayed more apathy, depression and irritability than noncarriers. Early symptomatic subjects had more apathy, but not more depression or irritability, compared to presymptomatic subjects. Advanced symptomatic subjects had more apathy than early symptomatic subjects.
Conclusions: The PBA is a reliable and sensitive instrument. Behavioural problems occur in all stages of HD and arise before the onset of motor symptoms. Apathy is related to disease severity, whereas depression and irritability are not. The broad clinical phenotype of HD therefore requires adequate service delivery with integrated and multidisciplinary patient care.