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Changes in decision making during normal aging and in Alzheimer's disease : links to executive functions, working memory and episodic memory

Year: 2022
Type: dissertation
Study design: Observational Study
Abstract: Both normal and pathological ageing lead to cognitive changes that can affect decision-making capacity (DMC). Although the elderly face many important decisions, to our knowledge, no study has systematically investigated the links between changes in DMC and changes in cognitive functions during ageing. Objective: The aim of this PhD thesis was double: 1) better specify the characteristics of DMC in elderly adults without neurocognitive disorders, as well as in elderly adults with mild Alzheimer's disease (AD); and 2) investigate the links between changes in DMC and changes in executive functions, working memory and episodic memory during normal ageing and mild AD. Method: Three studies were conducted, two interested in normal ageing and one in mild AD. In all studies, DMC was assessed using the Iowa Gambling Task (IGT) and a scenario task based on everyday life situations, comprising under-risk and under-ambiguity conditions. Study 1 aimed to understand the relationship that DMC shares with executive functions (i.e., mental flexibility, inhibition and updating) and working memory in normal ageing. Fifty adults aged between 62 and 87 years and 50 young adults aged between 18 and 32 years were included. Study 2 aimed to shed light on the relationship between DMC and episodic memory (i.e., recollection and familiarity processes) in normal ageing. Thirty adults aged between 60 and 83 years and 30 young adults aged between 18 and 30 years were included. Finally, using the same protocol as Study 1, Study 3 aimed to understand the relationship between DMC, executive functions and working memory in patients with mild AD. Twenty elderly control adults and 20 patients with mild AD were included. Results: Studies 1 and 2 showed that elderly adults had more difficulty adapting their decisions during IGT and that they were more risk and ambiguity-averse in the scenario task than young adults. In addition, elderly adults relied more on the percentage of certainty of the risky option, regardless of the context (i.e., gain vs. loss), than their younger counterparts. However, both young and elderly adults were sensitive to the context effect. Studies 1 and 2 respectively showed a particular involvement of inhibitory processes and familiarity processes on the ability to make decisions. Study 3 showed greater difficulty in maintaining a stable strategy on IGT in AD patients than in elderly control adults. For the scenario task, in the under-ambiguity condition, elderly adults with AD and controls had the same attitude towards ambiguity and adjusted their decisions equally to the percentage certainty of the unambiguous option. In the under-risk condition, AD patients adjusted their decision to the certainty percentages only in the gain condition. All of the cognitive functions assessed (i.e., inhibition, mental flexibility, updating, and working memory) accounted for some of the performances of elderly control adults and of AD patients on decision tasks. Discussion: Both normal ageing and mild AD lead to changes in DMC. Elderly adults with and without cognitive impairment make safer decisions than young adults. According to the Socioemotional Selectivity Theory, they tend to optimise their well-being. Already in the Mild AD already knows a weakening of the context effect. Partially challenging the model of Schiebener and Brand (2015), cognitive processes, that depend on the reflective mode, also seem to be involved in decision-making under ambiguity.
Language: English
Field: Medicine
Open Access status: green
OpenAlex ID: W4392531969
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