Phonemic fluency deficits in asymptomatic gene carriers for Huntington's disease

The aim of the present study was to investigate verbal fluency in preclinical Huntington's disease (HD). Phonemic and semantic fluency and the rate of word production over time were assessed for 29 asymptomatic gene carriers and 34 noncarriers of HD. The relationship between fluency tasks and other cognitive domains was investigated. Compared to noncarriers, carriers produced fewer words and produced them more slowly in the phonemic fluency task but not in the semantic fluency task. When the carrier group was divided on the basis of Predicted-Years-To-Onset (PYTO), only carriers with < 12 PYTO performed worse than noncarriers on both fluency tasks. Correlational analyses revealed that phonemic fluency was associated with cognitive speed and working memory, while semantic fluency was linked with crystallized abilities. The difference between carriers and noncarriers in phonemic fluency and a difference between the two carrier groups (< 12 PYTO and >= 12 PYTO) in semantic fluency, but not in phonemic fluency, suggest that frontostriatal deficits may precede temporal involvement in preclinical HD.