Neuropsychological characteristics of Huntington's disease carriers: a double blind study.

A cohort of 33 people at risk for Huntington's disease (HD), applying for genetic testing, were tested with a battery of neuropsychological tests covering attentional, visuospatial, learning, memory, and planning functions. A psychiatric rating scale, SCL-90R, was also applied, mainly as a control, since cognitive dysfunction could be ascribed to functional disorders as well as neurodegenerative processes. Self-rating did not indicate any psychiatric symptoms in carriers or non-carriers. However, significantly inferior cognitive functioning in the gene carriers was disclosed by the neuropsychological tests. Primarily, attentional, learning, and planning functions were affected. It is concluded that premorbid cognitive decline occurs in HD.