A Cochrane review [Abstract] 1 included 20 studies with a total of 986 subjects. A total of 966were patients with multiple sclerosis (MS), 20 were healthy controls. Most of the patients had relapsing-remitting type of disease. In only 13 studies cognitive impairment, either self reported, objectively demonstrated or both, was one of the inclusion criteria. The mean age was 44.6 years, the mean Expanded Disability Status Scale (EDSS) score was 3.2 and the mean duration of disease was 14.0 years. Cognitive training was included in 90% of the studies and described for 5 domains: memory, attention, visuospatial, executive functions and problem-solving skills. Two studies (10%) not using neuropsychological rehabilitation used cognitive-behavioural intervention to reduce behavioural problems and notebooks to intensify the observation of institutionalised patients' needs. The control group received no intervention in 13 studies and unspecific cognitive training in 5 studies. Duration of rehabilitation intervention was from 4 weeks to 6 months. The primary target was usually memory function, either alone or together with other functions. In 11 studies the outcome was measured within a month post-treatment and in 9 studies follow-ups varied from 11 weeks to one year post-treatment (mean 25.3 weeks). Cognitive training was found to improve memory span (SMD 0.54, 95% CI 0.20 to 0.88; 2 trials, n=150) and working memory (SMD 0.33, 95% CI 0.09 to 0.57; 3 trials, n=288). Cognitive training combined with other neuropsychological rehabilitation methods was found to improve attention (SMD 0.15, 95% CI 0.01 to 0.28; 10 studies, n=894), immediate verbal memory (SMD 0.31, 95% CI 0.08 to 0.54; 6 studies, n=308) and delayed memory (SMD 0.22, 95% CI 0.02 to 0.42; 4 studies, n=400). There was no evidence of an effect of neuropsychological rehabilitation on emotional functions.
Comment: The quality of evidence is downgraded by study quality (inadequate allocation concealment), inconsistency (heterogeneity in population, interventions and outcomes) and indirectness (differences in studied patients, part of the studies included neuropsychologically intact persons and short follow-up time) and upgraded by large magnitude of effect.
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