Psychiatric symptoms are more prevalent in Huntington's disease (HD) than the general population, but reasons for this are unknown. The primary aim of this research was to investigate possible familial influences on the psychiatric phenotype in HD.
96 gene positive and 5 gene negative siblings were recruited from 50 HD families throughout the UK and underwent a lifetime psychiatric history assessment using semi-structured interview and case-note review.
Gene positive index individuals had high lifetime rates of depressive (56%) and anxiety (38%) disorders. Their depressive episodes were less severe and more frequent with an older age of onset and fewer biological symptoms than individuals with depression without HD. Within gene positive sibling-pairs (n=53), there was significant familial aggregation of the presence (ĸ=0.46, p=0.004) and course (ICC=0.47, p=0.002) of depressive disorders and the presence of irritability (ĸ=0.357, p=0.024) and aggression (ĸ=OJ84, p=O.Ol6). Two gene negative siblings had lifetime psychiatric diagnoses.
The high prevalence of psychiatric co-morbidity in HD cannot be entirely explained by the HD gene. Familial factors, most likely other genetic factors, are likely to play a role. Further research into the contribution of biological and environmental factors to the psychiatric phenotype in large samples of individuals with HD is warranted
