The Guaranteed Euros: Probabilistic Discounting in Behavioural-Variant Frontotemporal Dementia.

Financial decision-making requires trading off between guaranteed and probabilistic outcomes and between immediate and delayed ones. While research has demonstrated that patients with behavioural-variant frontotemporal dementia (bvFTD) prefer immediate rewards at the expense of future ones (i.e. temporal discounting), little is known about how patients choose between smaller, guaranteed and larger, but probabilistic, outcomes (i.e. probabilistic discounting). We thus investigated probabilistic discounting by inviting 18 patients with bvFTD and 20 control participants to choose between fixed smaller monetary amounts and a fixed larger monetary amount with a variated probability of occurrence (e.g. 'Would you rather have 40euro for sure or a 20% chance of winning 100euro?'). Results demonstrated lower scores, indicating higher risk tolerance, on the probabilistic discounting task in patients with bvFTD (while impulsively choosing more immediate rewards on the temporal discounting task) compared to control participants. Probabilistic discounting was significantly correlated with a decline in general cognitive performance in patients with bvFTD. When dealing between smaller, guaranteed, and larger, but probabilistic, rewards, patients with bvFTD tend to prefer guaranteed rewards and discount the uncertain ones.