Survey-based assessment of the relationship between cognitive impairment and mentally stimulating activity in multiple sclerosis

Systematic review of cognitive reserve in multiple sclerosis: Accounting for physical disability, fatigue, depression, and anxiety

BACKGROUND

Cognitive reserve (CR) describes an individual's ability to adapt cognitive processes in response to brain atrophy, and has been reported to explain some of the discrepancy between brain atrophy and cognitive functioning outcomes in multiple sclerosis (MS). CR in MS is typically investigated by assessing an individual's pre- and/or post-diagnosis enrichment, which includes premorbid intellectual abilities, educational level, occupational attainment, and engagement in cognitively enriching leisure activities. Common MS symptoms (e.g., physical disability, fatigue, depression, anxiety) may impact an individual's ability to engage in various CR-enhancing activities post-diagnosis. It is unknown to what extent these MS symptoms have been taken into account in MS research on CR. As such, we identified whether studies assessed CR using measures of premorbid or continuous (including post-diagnosis) enrichment. For studies investigating continuous enrichment, we identified whether studies accounted for MS-impact, which MS symptoms were accounted for, and how, and whether studies acknowledged MS symptoms as potential CR-confounds.

METHODS

Three electronic databases (PsycINFO, PubMed, Scopus) were searched. Eligible studies investigated CR proxies (e.g., estimated premorbid intellectual abilities, vocabulary knowledge, educational level, occupational attainment, cognitively enriching leisure activities, or a combination thereof) in relation to cognitive, brain atrophy or connectivity, or daily functioning outcomes in adult participants with MS. We extracted data on methods and measures used, including any MS symptoms taken into account. Objectives were addressed using frequency analyses and narrative synthesis.

RESULTS

115 studies were included in this review. 47.8% of all studies investigated continuous enrichment. Approximately half of the studies investigating continuous enrichment accounted for potential MS-impact in their analyses, with only 31.0% clearly identifying that they treated MS symptoms as potential confounds for CR-enhancement. A narrative synthesis of studies which investigated CR with and without controlling statistically for MS-impact indicated that accounting for MS symptoms may impact findings concerning the protective nature of CR.

CONCLUSION

Fewer than half of the studies investigating CR proxies in MS involved continuous enrichment. Just over half of these studies accounted for potential MS-impact in their analyses. To achieve a more complete and accurate understanding of CR in MS, future research should investigate both pre-MS and continuous enrichment. In doing so, MS symptoms and their potential impact should be considered. Establishing greater consistency and rigour across CR research in MS will be crucial to produce an evidence base for the development of interventions aimed at improving quality of care and life for pwMS.

A mixed-methods study of cognitive performance in persons with multiple sclerosis: Association between neuropsychological test performance and interviews about daily cognitive functioning

BACKGROUND

Cognitive difficulties are commonly reported in persons with multiple sclerosis (MS), however, self-reports of cognition often do not correspond well to objective neuropsychological test performance. The use of qualitative interviews can allow for persons with MS to describe in more detail how their cognitive function is impacted in daily life while also taking into consideration personal and environmental influences. No study to our knowledge has examined the association between objective neuropsychological test performance and qualitative interview reports of daily cognitive function. Such information could help explain the reported lack of correspondence between these two methods of evaluating cognitive function in MS.

OBJECTIVE

To investigate the relationship between objective neuropsychological test performance and qualitative interview reported daily cognitive function in persons with MS .

METHODS

Convergent parallel mixed-methods design whereby 12 persons with MS (mean age= 47, 9 female, 7 relapsing-remitting MS) took part in a 2-hour neuropsychological assessment [including the Brief International Cognitive Assessment for MS (BICAMS)] followed by a semi-structured qualitative interview probing daily cognitive functioning. Interview data were analysed using thematic analysis. Interview codes and themes were compared with neuropsychological performance on respective cognitive domains and between those with and without cognitive impairment on the BICAMS.

RESULTS

Based on the qualitative interview data, the most commonly reported difficulties were related to memory, word finding, and processing speed but only 43%, 0%, and 33% of the individuals reporting these deficits actually demonstrated impairment on the respective/ corresponding neuropsychological measures. Eleven of the twelve participants reported the use of strategies to manage cognitive difficulties. The most frequently reported strategies used were related to fatigue management. Personal (age, fatigue) and environmental factors (pressure of daily responsibilities, availability of support) were reported as influencers of daily cognitive function. Three of the 12 participants were classified as cognitively impaired on the BICAMS but they did not differ from those who were non-impaired with respect to use of strategies, and influence of personal and environmental factors on daily cognitive functioning.

CONCLUSIONS

Interview-reported daily cognitive difficulties did not correspond well to objective neuropsychological performance. Greater emphasis should be placed on utilizing and developing objective neuropsychological measures that have greater sensitivity, particularly to word finding difficulties in MS, and to the incorporation of personal and environmental factors into the interpretation of neuropsychological test results. As almost all participants reported the use of cognitive strategies, we feel greater emphasis needs to be placed on patient education of evidence-based strategies, particularly focused on highly reported impacted word finding and processing speed abilities.

Coming off cannabis: a cognitive and magnetic resonance imaging study in patients with multiple sclerosis

Cognitive dysfunction affects 40-80% of patients with multiple sclerosis. Smoking cannabis may add to these deficits. It is unclear whether coming off cannabis results in cognitive improvement. To address this question, 40 patients with multiple sclerosis who started using cannabis after the onset of multiple sclerosis and who used it for at least 4 days a week over many years were divided by odd-even number selection into two groups: cannabis continuation and cannabis withdrawal. Assessments took place at baseline and after 28 days and included serial versions of the Brief Repeatable Neuropsychological Battery for multiple sclerosis containing tests of verbal and visual memory, processing speed and executive function; structural and functional MRI, the latter entailing a compatible version of the Symbol Digit Modalities Test; urine for cannabinoid metabolites to detect compliance with abstinence. Only those participants deemed globally impaired at baseline (failure on at least two cognitive domains) were enrolled. The results revealed that the two groups were well matched demographically and neurologically. One subject was removed from the withdrawal group because of failed abstinence. Urine analysis revealed the cannabinoid consumed was predominantly tetrahydrocannabinol (THC). There were no baseline between group cognitive differences, but by Day 28 the withdrawal group performed significantly better on every cognitive index (P < 0.0001 for all). Significant within group differences were present for every test over time, but only in the abstinent group (P < 0.0001 for all tests). There were no between group baseline or Day 28 differences in structural MRI indices (global atrophy, total T1 and T2 lesion volume). At index assessment the two groups had a similar performance on the functional MRI-compatible Symbol Digit Modalities Test and there were no group differences in brain activation. However, by Day 28, the withdrawal group completed more trials correctly (P < 0.012) and had a faster reaction time (P < 0.002), associated with significantly increased activation in brain regions known to be associated with performance of the test (bilateral inferior frontal gyri, caudate and declive/cerebellum, P < 0.001 for all regions). These results reveal that patients with multiple sclerosis who are frequent, long-term cannabis users can show significant improvements in memory, processing speed and executive function after 28 days of drug abstinence. The absence of similar improvements in a matched multiple sclerosis group that remained on cannabis shows that beneficial cognitive change after stopping cannabis is not solely attributable to the effects of practice.