IMPAIRED RECOGNITION OF DISGUST IN HUNTINGTONS-DISEASE GENE CARRIERS

Face processing and facial expression recognition were investigated in the earliest stages of Huntington's disease, by studying 40 people wh o presented for genetic testing. Twenty-three of these 'at risk' indiv iduals turned out not to carry the gene for Huntington's disease (the AR(-) group). Seventeen were found to be gene carriers (the AR(+) grou p); 15 from generic testing, and two who showed signs of early stages of Huntington's disease. A number of standard tasks were used to provi de background information, including recognition memory for words, pic ture naming, verbal fluency, and figure copying; none revealed signifi cant differences between AR(+) and AR(-) groups. Face processing abili ties were investigated using tests of identification of familiar (famo us) faces, unfamiliar face matching, recognition memory for faces, and recognition of facial expressions of emotion. No statistically signif icant differences between the AR(+) and AR(-) groups were found for an y of these tests, but the AR(+) group showed a borderline overall impa irment in recognizing facial expressions of emotion (0.05 < P < 0.1). When recognition of each of the six basic emotions used was examined s eparately only disgust was found to be significantly impaired. This hi ghly selective deficit in the recognition of disgust was confirmed in the subgroup of 15 individuals shown by genetic testing to be Huntingt on's gene carriers; it was therefore found in people who were free fro m clinical symptoms and did not perform significantly more poorly than non-carriers on any of the background tests, on any of the other face processing tasks, and even for recognition of any other basic emotion . This points strongly to the importance of the basal ganglia in the e motion of disgust.