Risky decision-making in dementia: exploring neural correlates and related clinical symptoms.

Background: Appropriately balancing potential risks versus rewards is important for affective decision-making in everyday life. Impaired affective decision-making on risk-taking tasks has been reported in individuals with dementia, but the neural correlates of such deficits, and whether they relate to neuropsychiatric symptoms, such as disinhibition and apathy, have not been directly examined.

Methods: Forty-one behavioural-variant frontotemporal dementia (bvFTD), 28 Alzheimer's disease (AD) patients and 42 healthy controls completed the Balloon Analogue Risk Task (BART), which assessed their ability to weigh risks versus rewards to maximise monetary earnings. Informant-reported measures of disinhibition and apathy were completed. All participants underwent structural magnetic resonance imaging brain scans.

Results: While bvFTD and AD patients showed some impairments on the BART relative to controls, a high degree of variability was observed within patient groups. Poorer BART performance was associated with bilateral medial prefrontal and orbitofrontal cortex atrophy. A hierarchical cluster analysis revealed four groups of patients, with distinct patterns of BART performance, varying levels of disinhibition and apathy, and divergent patterns of brain atrophy. The group that showed the worst performance on the BART (i.e., collected the least money and popped the most balloons) showed the greatest disinhibition and orbitofrontal cortex atrophy.

Conclusions: Our findings highlight the heterogeneous nature of affective decision-making deficits in dementia and uncover important links between BART performance, symptoms of disinhibition and apathy, and orbitofrontal cortex atrophy. Greater understanding of these symptom profiles and underlying neurocognitive mechanisms may help to inform potential management strategies for impaired affective decision-making in dementia.