Why Cognitive–Cognitive Dual-Task Testing Assessment Should Be Implemented in Studies on Multiple Sclerosis and in Regular Clinical Practice

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.

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.

On the Reliability of Examining Dual-Tasking Abilities Using a Novel E-Health Device—A Proof of Concept Study in Multiple Sclerosis

The assessment of neuropsychological functions and especially dual-tasking abilities is considered to be increasingly relevant in the assessment of neurological disease, and Multiple Sclerosis (MS) in particular. However, the assessment of dual-tasking abilities is hindered by specific software requirements and extensive testing times. We designed a novel e-health (progressive web application-based) device for the assessment of dual-tasking abilities usable in “bedside” and outpatient clinic settings and examined its reliability in a sample of N = 184 MS patients in an outpatient setting. Moreover, we examined the relevance of dual-tasking assessment using this device with respect to clinically relevant parameters in MS. We show that a meaningful assessment of dual-tasking is possible within 6 min and that the behavioral readouts overall show good reliability depending on dual-tasking difficulty. We show that dual-tasking readouts were correlated with clinically relevant parameters (e.g., EDSS, disease duration, processing speed) and were not affected by fatigue levels. We consider the tested dual-tasking assessment device suitable for routine clinical neuropsychological assessments of dual-tasking abilities. Future studies may further evaluate this test regarding its suitability in the long-term follow up assessments and to assess dual-tasking abilities in other neurological and psychiatric disorders.