No abstract

Cognitive decline is recognized as a prevalent and debilitating symptom of multiple sclerosis (MS), especially deficits in episodic memory and processing speed. The field aims to (1) incorporate cognitive assessment into standard clinical care and clinical trials, (2) utilize state-of-the-art neuroimaging to more thoroughly understand neural bases of cognitive deficits, and (3) develop effective, evidence-based, clinically feasible interventions to prevent or treat cognitive dysfunction, which are lacking. There are obstacles to these goals. Our group of MS researchers and clinicians with varied expertise took stock of the current state of the field, and we identify several important practical and theoretical challenges, including key knowledge gaps and methodologic limitations related to (1) understanding and measurement of cognitive deficits, (2) neuroimaging of neural bases and correlates of deficits, and (3) development of effective treatments. This is not a comprehensive review of the extensive literature, but instead a statement of guidelines and priorities for the field. For instance, we provide recommendations for improving the scientific basis and methodologic rigor for cognitive rehabilitation research. Toward this end, we call for multidisciplinary collaborations toward development of biologically based theoretical models of cognition capable of empirical validation and evidence-based refinement, providing the scientific context for effective treatment discovery.

We provide longitudinal support for theories of brain reserve and cognitive reserve in MS. Larger MLBG protects against decline in cognitive efficiency, and greater intellectual enrichment protects against decline in cognitive efficiency and memory. Consideration of these protective factors should improve prediction of future cognitive decline in patients with MS.

Despite the importance of good lecture notes to test performance, very little is known about the cognitive processes that underlie effective lecture note taking. The primary purpose of the 2 studies reported (a pilot study and Study 1) was to investigate 3 processes hypothesized to be significantly related to quality of notes: transcription fluency, verbal working memory, and the ability to identify main ideas. A 2nd purpose was to replicate the findings from previous research that notes and verbal working memory were significantly related to test performance. Results indicated that transcription fluency was the only predictor of quality of notes and that quality of notes was the only significant predictor of test performance. The findings on transcription fluency extend those of the children's writing literature to indicate that transcription fluency is related to a variety of writing outcomes and suggest that interventions directed at transcription fluency may enhance lecture note taking.

The cognitive reserve hypothesis helps to explain the incomplete relationship between brain disease and cognitive status in people with neurologic diseases, including Alzheimer's; disease and multiple sclerosis. Lifetime intellectual enrichment (estimated with education or vocabulary knowledge) lessens the negative impact of brain disease on cognition, such that people with greater enrichment are able to withstand more severe neuropathology before suffering cognitive impairment or dementia. The current research is the first to investigate directly the relationship between intellectual enrichment and an index of cerebral activity (the blood oxygen level dependent signal) in a neurologic sample. Multiple sclerosis patients completed a vocabulary-based estimate of lifetime intellectual enrichment. Disease severity was estimated with brain atrophy. Cognitive status was measured with the Symbol Digit Modalities Test. Cerebral activity (functional magnetic resonance imaging blood oxygen level dependent signal) and behavioural performance (accuracy, reaction time) were recorded during the visual N-Back working memory task (three levels of demand: 0-, 1-, 2-Back). All patients produced perfect/nearly perfect accuracy during lower demands (0- and 1-Back), and reaction time was unrelated to intellectual enrichment; however, voxelwise partial correlations controlling for brain atrophy revealed strong positive correlations between intellectual enrichment and cerebral activity within the brain's; default network (e.g. anterior and posterior cingulate corticies), indicating that patients with greater enrichment were able to maintain resting state activity during cognitive processing better. In turn, intellectual enrichment was negatively associated with prefrontal recruitment, suggesting that patients with lesser enrichment required more cerebral resources to perform the same cognitive task as patients with greater enrichment. This same pattern of enrichment-related cerebral activity was observed when cognitive demands increased (2-Back), and intellectual enrichment was negatively associated with reaction time. Principle components analysis revealed a single cognitive reserve network across tasks (greater default network, lesser prefrontal recruitment). Expression of this network almost fully mediated the positive relationship between intellectual enrichment and cognitive status (Symbol Digit Modalities Test). Also, expression of this network was positively associated with brain atrophy when controlling for cognitive status, indicating that patients with greater expression of this network can withstand more severe brain disease before exhibiting cognition similar to patients with lesser network expression. Of note, similar functional magnetic resonance imaging research with healthy adults has not found an association between intelligence and cerebral efficiency. The unique relationship between intellectual enrichment and cerebral efficiency in neurologic patients is consistent with the cognitive reserve hypothesis, which does ...

Objective: We first tested the brain reserve (BR) hypothesis in multiple sclerosis (MS) by examining whether larger maximal lifetime brain volume (MLBV; determined by genetics) protects against disease-related cognitive impairment, and then investigated whether cognitive reserve (CR) gained through life experience (intellectually enriching leisure activities) protects against cognitive decline independently of MLBV (BR).Methods: Sixty-two patients with MS (41 relapsing-remitting MS, 21 secondary progressive MS) received MRIs to estimate BR (MLBV, estimated with intracranial volume [ICV]) and disease burden (T2 lesion load; atrophy of gray matter, white matter, thalamus, and hippocampus). Early-life cognitive leisure was measured as a source of CR. We assessed cognitive status with tasks of cognitive efficiency and memory. Hierarchical regressions were used to investigate whether higher BR (ICV) protects against cognitive impairment, and whether higher CR (leisure) independently protects against cognitive impairment over and above BR. ) showed that leisure independently attenuated the impact of disease burden on cognition. Follow-up analyses revealed that BR protected against cognitive inefficiency, not memory deficits, whereas CR was more protective against memory deficits than cognitive inefficiency. Conclusion:We provide evidence of BR in MS, and show that CR independently protects against disease-related cognitive decline over and above BR. Lifestyle choices protect against cognitive impairment independently of genetic factors outside of one's control.

According to the cognitive reserve hypothesis, neuropsychological expression of brain disease is attenuated among persons with higher education or premorbid intelligence. The current research examined cognitive reserve in multiple sclerosis (MS) by investigating whether the negative effect of brain atrophy on information processing (IP) efficiency is moderated by premorbid intelligence. Thirty-eight persons with clinically definite MS completed a vocabulary-based estimate of premorbid intelligence (Wechsler Vocabulary) and a composite measure of IP efficiency (Symbol Digit Modalities Test and Paced Auditory Serial Addition Task). Brain atrophy was estimated from measurements of third ventricle width using high-resolution anatomical brain magnetic resonance imaging (magnetization-prepared rapid gradient echo). In a hierarchical regression analysis controlling for age and depressive symptomatology, brain atrophy predicted worse IP efficiency (R2 = .23, p = .003) and cognitive reserve predicted better IP efficiency (R2 = .13, p = .013), but these effects were moderated by an Atrophy x Cognitive Reserve interaction (R2 = .15, p = .004). The negative effect of brain atrophy on IP efficiency was attenuated at higher levels of reserve, such that MS subjects with higher reserve were better able to withstand MS neuropathology without suffering cognitive impairment. Results help explain the incomplete and inconsistent relationship between brain atrophy and IP efficiency in previous research.

Cognitive impairment is common among persons with multiple sclerosis (MS), but some patients are able to withstand considerable disease burden (e.g. white matter lesions, cerebral atrophy) without cognitive impairment (cognitive inefficiency, memory decline). What protects these patients from cognitive impairment? We review the literature on cognitive reserve in MS, which shows that heritable (larger maximal lifetime brain growth) and environmental (greater intellectual enrichment) factors attenuate the negative effect of disease burden on cognitive status. That is, persons with larger maximal lifetime brain growth, greater vocabulary knowledge, and/or greater early life participation in cognitive leisure activities (e.g. reading, hobbies) are better able to cope with MS disease without cognitive impairment. We review evidence that benefits of intellectual enrichment on cognitive status may stem from more efficient patterns of brain function. We discuss clinical implications and highlight important unanswered questions for future research on reserve against cognitive impairment in MS.