Contrary to popular belief, receiving a diagnosis of a devastating fatal disease does not exacerbate, and may even alleviate, the risk of suicide. Suicidal ideation was examined in 4,171 individuals in the Huntington Study Group database. Participants were grouped according to a standardized neurological examination from 0 (i.e., normal examination) to 3 (definite Huntington's disease). Patients with an unequivocal diagnosis of Huntington's disease were further divided by stage of disease, from stage 1 (early) to stage 5 (end stage). Findings showed that the frequency of suicidal ideation doubled from 9.1% in at-risk persons with a normal neurological examination to 19.8% in at-risk persons with soft neurological signs and increased to 23.5% in persons with "possible Huntington's disease." In persons with a diagnosis of Huntington's disease, 16.7% had suicidal ideation in stage 1, and 21.6% had suicidal ideation in stage 2, whereas the proportion of Huntington's disease patients with suicidal ideation diminished thereafter. Findings suggest two critical periods for increased risk of suicide in Huntington's disease. The first critical period is immediately before receiving a formal diagnosis of Huntington's disease, and the second is in stage 2 of the disease, when independence diminishes. Although the underlying mechanisms of suicidal ideation in Huntington's disease are poorly understood, it is critical for health care providers to be aware of periods during which patients may be at an increased risk.

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Associations between two types of measures of executive functions, namely, neuropsychological and personality, and measures of real-world behavior were investigated. Undergraduate students were administered neuropsychological measures of executive functions and completed a personality questionnaire developed to measure traits central to the construct of executive functions. Participants also reported on their behavior. Hierarchical regressions indicated that neuropsychological and personality measures of executive functions were significant predictors of different types of behavior. Neuropsychological measures predicted work behaviors and personality measures predicted substance use, risk-taking, and aggressive behaviors. Findings highlight the importance of including personality assessment in standard neuropsychological assessment in order to maximize ability to predict real-world behaviors relevant to independent and socially responsible functioning.

Engaging in conversation diverts attention from cognitive processes associated with driving. Drivers tend to commit errors that may lead to crashes when their attention is focused away from the driving task. The interference occurs at the level of central attentional processes that are especially susceptible to aging. The current study assessed the effects of a controlled auditory—verbal processing load induced by the Paced Auditory Serial Addition Task (PASAT) on vehicle control by 160 legally licensed older drivers. Of these drivers, 78 were neurologically normal (mean age of 71 years) and 82 (mean age of 75 years) had impairments of selective attention but no diagnosable neurological disease. Measurements aboard the instrumented vehicle Automobile for Research in Ergonomics and Safety showed that performing the PASAT reduced speed and steering control of the older drivers relative to baseline (no-task) driving conditions and was associated with greater counts of at-fault safety errors. Yet, driving performance did not differ significantly between neurologically normal and attention-impaired older drivers between PASAT and no-PASAT (baseline) conditions. It may be that the PASAT, which involves auditory-verbal and working-memory, sustained-attention, and executive-function components, commands different resources than driving on uneventful highways, which might rely on overlearned, automatic cognitive processes. Interference produced by PASAT, like that of cell phone operation, might become more evident during demanding driving conditions, as exist at busy traffic intersections. Relevant studies in these potentially unsafe circumstances can be conducted in a driving simulator, as in our ongoing research on older drivers.

Two experienced drivers who developed severe amnesia due to bilateral hippocampal lesions participated in a series of standardized challenges of driving performance and knowledge of driving rules. During drives in a high fidelity simulator and on the road in an instrumented vehicle, they demonstrated vehicle control similar to that of normal drivers on measures of steering, speed control, safety errors, and driving with distraction. Their knowledge of driving rules, safety procedures, and road sign meaning also was normal. However, both participants were impaired at following route directions, and both had unsafe responses in a difficult crash avoidance scenario on the simulator. These findings suggest that memory impairment acquired by experienced drivers does not impair most aspects of driving performance, but may increase safety risk under some challenging circumstances.