Abstract
Objective: Research suggests that prospective memory (PM) is impaired from the very early stages of Alzheimer’s disease (AD). We sought to further characterize this impairment in patients with mild AD, using a virtual reality (VR) task to provide ecological assessment of PM.Methods: Fifteen cognitively normal older individuals (76.47 years old ± 4.14, MMSE: 28.80 ± 1.21), and 17 patients with mild AD (79.29 years old ± 4.45, MMSE: 22.82 ± 2.83) were asked to recall the prospective and retrospective components of seven intentions in a virtual town task. Six intentions were event-based, where the prospective cue was either highly (three intentions) or weakly (three intentions) associated with the retrospective component. The remaining intention was time-based. All participants completed a neuropsychological assessment of episodic memory, semantic memory and executive functioning. Non-parametric tests were used to compare the two groups on the different intentions types and components. Correlations between cognition and PM scores were then realized to further understand the cognitive correlates of the PM impairment in patients with AD.Results: Overall, patients with Alzheimer disease recalled fewer intentions than controls, with the retrospective component and time-based intentions being the most challenging for them. The strength of the association between the prospective and retrospective components, however, had no effect on their performance. Event-based PM impairment, as well as deficit in the recall of prospective component correlated with memory and executive functions performance.Conclusion: PM is impaired in AD. Both automatic and controlled processes of PM retrieval are disturbed. This study also confirms the reliability of VR for assessing complex cognitive functions such as PM.
Highlights
Sporadic Alzheimer’s disease (AD) is a progressive neurodegenerative pathology that mainly affects individuals over 65 years
While previous findings suggested that patients with mild AD exhibit comparable impairments in the recall of both components of intentions (Jones et al, 2006), our results indicate that the recall of the retrospective component is more challenging than that of the prospective component in early AD
This study demonstrates the relevance of Virtual reality (VR)-based tasks for assessing prospective memory (PM) in patients with AD
Summary
Sporadic Alzheimer’s disease (AD) is a progressive neurodegenerative pathology that mainly affects individuals over 65 years. Despite advances in the analysis of cerebrospinal fluid and neuroimaging biomarkers, neuropsychological assessments remain an essential diagnostic tool in order to detect the earliest cognitive and behavioral critical symptoms of AD. Diagnosis of AD remains an important issue as it enables caregivers to plan the management of the disease and to provide tailored interventional therapies (Buracchio and Kaye, 2009). Episodic memory impairment is usually described as the key symptom of disease onset and remains a major criterion for the diagnosis of probable AD (McKhann et al, 1984, 2011; Dubois et al, 2014). Forgetfulness of intentions has been found as an early hallmark of AD (Jones et al, 2006). Prospective memory (PM) assessments are still rare in clinical practice
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