Transforming a Concept in a Tool: Diagnostic and Prognostic Value of Tasks Depleting Cognitive Resources

Cognitive-Cognitive Dual-task in aging: A cross-sectional online study

The prevalence of neurodegenerative disorders, particularly dementia, is on the rise across many countries worldwide. This negative trend calls for improving our understanding of cognitive aging. While motor-cognitive dual-task approaches have already been proven valuable for clinical diagnosis, comparatively less research is available on the application of Cognitive-Cognitive Dual-Tasking (CCDT), across several cognitive domains. Moreover, there is limited understanding about how healthy aging affects performance in such dual-tasks in the general population. CCDT entails engaging individuals in multiple cognitive tasks simultaneously and holds promise for remote e-Health interventions. In this cross-sectional study, our objective was to evaluate the suitability of a newly developed, self-administered, online tool for examining age-related differences in memory performance under dual-tasking. 337 healthy adults aged 50-90 underwent a visual memory test (Memo) under both single and dual-task conditions (attend to auditory letters). Additional measures included questionnaires on subjective memory complaints (MAC-Q), on cognitive reserve (CR), and a cognitive screening (auto-GEMS). As expected, the accuracy of visual memory performance exhibited a negative correlation with age and MAC-Q, and a positive correlation with CR and auto-GEMS scores. Dual-tasking significantly impaired performance, and its detrimental effect decreased with increasing age. Furthermore, the protective effect of cognitive reserve diminished with advancing age. These findings suggest that the commonly observed age-related increase in dual-task costs is not universally applicable across all tasks and cognitive domains. With further refinement, a longitudinal implementation of this approach may assist in identifying individuals with a distinct cognitive trajectory and potentially at a higher risk of developing cognitive decline.

Scoping review of dual-task interference in individuals with intellectual disability

Dual-task paradigms can provide insights on the structures and mechanisms underlying information processing and hold diagnostic, prognostic, and rehabilitative value for populations with cognitive deficits such as in individuals with intellectual disability (ID). In this paradigm, two tasks are performed separately (single-task context) and concurrently (dual-task context). The change in performance from single- to dual-task context represents dual-task interference. Findings from dual-task studies have been largely inconsistent on whether individuals with ID present with dual-task-specific deficits. The current review aimed to map the published literature on dual-task methods and pattern of dual-task interference in individuals with ID. A scoping review based on Arksey and O'Malley's five-stage methodological framework was performed. Seventeen electronic databases and registries were searched to identify relevant studies, including gray literature. Charted data from included studies were analyzed quantitatively and qualitatively. PRISMA guidelines informed the reporting of this review. Twenty-two studies involving 1,102 participants (656 with ID and 446 without ID) met the review's inclusion criteria. Participants in the included studies were heterogeneous in sex, age (range 3-59 years), etiology and ID severity. Included studies characterized their ID-sample in different ways, most commonly using intelligence quotient (IQ) scores. Other measures of intellectual function (e.g., mental age, ID severity, verbal and/or visuospatial ability scores) were also used, either solely or in combination with IQ. Methods of dual-task testing varied across studies, particularly in relation to dual-task combinations, equation of single-task performance between groups, measurement and reporting of dual-task performance for each single-task, and task priority instructions. Thematic content of the included studies were: (1) structural interference to dual-tasking; (2) etiology-based differences in dual-tasking; (3) gait and balance dual-task performance; (4) testing executive function using dual-task paradigms; and (5) training effect on dual-task performance. Although the evidence consistently supported the intact dual-tasking ability of individuals with ID, the pattern of dual-task interference was inconsistent. Likewise, the evidence was inconclusive regarding dual-task deficit specific to individuals with ID because of heterogeneity in dual-task study designs among included studies.

Multitasking Effects on Perception and Memory in Older Adults

Performing multiple tasks in parallel is detrimental to performance, a phenomenon generically referred to as dual-task interference (DTi). Several variables can modulate DTi at the individual level, and increasing age is typically described as negatively affecting response costs. In this study, we investigated, in 252 healthy adults aged between 50 and 89 years, how age modulates the detrimental effect of DTi during the encoding of images. We combined a visual memory task and a sustained attention task (i.e., an auditory version of the continuous performance task, ACPT) in three separate blocks. In the first block, participants had to perform a four-alternative forced-choice recognition of previously memorized images without having attended to ACPT sounds during the encoding. In the second block, during memorization, participants had to press a response key when detecting the letter "X" within a stream of letters (Low Load). In the third block, they had to respond only when the letter "X" was preceded by the letter "A" (High Load). The results showed that overall performance linearly decreased with age. In contrast with our predictions, DTi was stable across different ages. Finally, using a cluster-based approach, we found that participants who paid the highest costs when dual-tasking also demonstrated, on a self-administered cognitive screening significantly lower scores than peers. These new types of tests, which ask for concurrent task performance, might become useful for detecting outlier performance that might anticipate or correlate with aging-related cognitive decline.