Cognitive Impairment

There is lots to be gained from preventing worsening of cognitive impairment in MS. #MSBlog #MSResearch

“The paper below is interesting. It is a mixed systemic review on definitions of cognitive impairment in MSers and a study testing these criteria. The bad news is that cognitive impairment occurs in early MS, which we already know. The good news is that the prevalence of cognitive impairment depends on how you define it. It is clear from this relatively small study (25 MSers with early MS and 52 MSers with late MS) that when cognitive impairment is found in early MS it is relatively mild. This is good news and implies that there is a lot to be gained by preventing further damage and to protect cognition from getting worse. This is why I refer to MS as being a preventable dementia.”

Epub: Fischer et al. How reliable is the classification of cognitive impairment across different criteria in early and late stages of multiple sclerosis? J Neurol Sci. 2014 May 27. pii: S0022-510X(14)00332-3. doi: 10.1016/j.jns.2014.05.042.

BACKGROUND: Prevalence rates of cognitive impairment (CI) in MS vary between 40% and 80%. Differences in classification criteria for CI may explain this variance.

OBJECTIVE: This study reviewed and compared classification criteria for CI in patients with early and late MS.

METHODS: The paper consists of two parts: a systematic review of published classification criteria and the presentation of new data. Criteria were reviewed in respect to percentage of abnormal parameters and cut-offs concerning standard deviations. Thereafter, criteria were applied to cognitive data of 25 MSers with early MS (duration ≤ 2y), 52 matched MSers with late MS (≥12y), and 75 matched controls. The test battery assessed alertness, divided attention, mental flexibility, verbal and visual learning, memory, and visuospatial abilities.

RESULTS: Seventy classification criteria were revealed and grouped into 20 distinct approaches that can be subdivided into three basic classification strategies. Most commonly, CI was defined as performing 1.5 SD or 2 SD below the normative mean in 18-30% of test parameters (n=42). Other criteria utilized cognitive domains (n=6), composite indices (n=8), or combinations of cut-offs and strategies. The stringency of the criteria was correlated with the prevalence rate of CI (r=-.43) and disease duration (r=.48). In the new data, a substantial effect of classification criteria was found with a prevalence rate ranging from 0 to 68% in early and 4 to 81% in late MS. Increased rates of CI in patients vs. controls were found following 18 out of 20 criteria in the sample of late MS. In early MS, an increased rate of CI was only found following a liberal 1.5 SD cut-off criterion. Inter-rater reliability between all criteria was moderate. However, between criteria of comparable stringency the inter-rater reliability was found to be strong.

CONCLUSION: Classification based on different published criteria is not fully comparable and criteria need to be better homogenized.

One thought on “Cognitive Impairment”

  1. It's not clear to me whether the late MS patients were tested at onset and then after 12 Years. I don't think of 12 years as late. Whenever I'm asked to take part in research I am asked what education level I reached. I worked with people who had degrees and those that didn't. It wasn't possible to identify their level of education although all doing really mentally demanding jobs. The cognitive impairment studies really need to up their game, before frightening people that need to just get on with their life.

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