Early Huntington’s Patients More Impulsive, but Show Normal Risk Behaviors

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by Alice Melão |

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Early HD and risk-taking

A recent report showed that patients with early Huntington’s disease (HD) cannot control their impulsiveness. However, when confronted with a risk-taking situation, they present a similar response as individuals without the disease. Recognizing this behavior pattern can have important implications during treatment and rehabilitation.

The study, “Early Huntington’s Disease: Impulse Control Deficits but Correct Judgment Regarding Risky Situations,” was published in the Journal of Huntington’s Disease.

Decision-making is a complex process that requires the brain to integrate several variables to accomplish profit and the desired benefits.

Huntington’s is characterized by the death of brain cells affecting different regions of the brain, including those that are involved in the decision-making process. However, it was still unclear whether Huntington’s patients could have judgment deficits, or if behavioral alterations are a result of impaired working memory, insensitivity to high losses, or impulse problems.

Based on the Cambridge gambling task (CGT) from the Cambridge Neuropsychological Test Automated Battery (CANTAB), the authors performed an analysis of decision-making and risk-taking behaviors of HD patients and compared them to individuals without the disease. Unlike other similar tests, CGT does not require working memory, so its results are not influenced by learning impairments.

The study included 19 patients diagnosed with early Huntington’s, Stage 1 or 2, from the Unified Huntington’s Disease Rating Scale (UHDRS), and 19 controls matched according to age, education and gender.

Both groups were found to choose the most probable outcome during testing with no significant differences in the deliberation time. However, when presented with the possibility of a high reward, HD patients could not resist the impulse to respond, showing a faster reaction time compared to the control group. The results suggested that early HD patients were not taking a genuine risk behavior, but were incapable of controlling their impulses.

Previous studies showed that early Huntington’s disease patients have relative integrity in a brain region called the ventromedial prefrontal cortex. This region was found to be important for decision processes and was linked to successful performance in CGT. In part, this can explain the findings of the study.

“Our results suggest that early Huntington’s disease patients have an impaired impulse control; however, the correct judgment about risky situations is preserved,” the authors wrote.

These results can contribute to a better understanding of personality changes that can take place during the early stages of Huntington’s. It can also help improve rehabilitation strategies and drug therapies to rein in impulsive actions of patients.