We can predict when driving is no longer safe for people who have HD using standard neuropsychological measures

Early cognitive dysfunction in Huntington's Disease (HD) is typically of a subcortical frontal executive type, with bradyphrenia, poor spatial and working memory, poor planning and organization, a lack of judgment, and poor mental flexibility. Although there is literature suggesting a correlation between deficits in speed of processing, working memory and executive function on driving competency, there is little direct evidence comparing these declines on tests to actual driving skills.

The current study examines the utility of specific neuropsychological measures in predicting actual driving competency in patients with HD.

Fifty-two patients at the UConn Health HD Program underwent yearly neuropsychological evaluations and were included in this study. Four scales were chosen a priori to predict driving impairment because of their reported relationship to driving ability. Within each test category, subjects who scored below the threshold suggestive of neurological impairment were found to have results within the impaired range (1.5 standard deviations below corrective normative data). A referral to the Connecticut Department of Motor Vehicles (DMV) for a driving evaluation was subsequently made on patients who were found impaired on any two of these tests.

The authors found a strong relationship between scores on a simple battery of four neuropsychological tests and driving competency.

This short battery may prove of pragmatic value for clinicians working with people with HD and their families.