Cognitive assessment in MS.

Abstract

Cognitive impairment has been demonstrated at all stages and in all subtypes of multiple sclerosis (MS) and has a wide-ranging impact on the lives of those affected. It can influence participative, safety and disease outcomes [1], with the net result being an overall reduction in quality of life. Worryingly, about half of patients with an Expanded Disability Status Scale (EDSS) score as low as 3 are unemployed [2] suggesting that physical disability is not the only contributing factor. Large unselected samples have identified cognitive impairment in around 60% of participants treated in clinics, with a slightly lower prevalence (50%) in community samples [3]. The strongest predictors of cognitive impairment are EDSS, progressive course of MS and age [3]. Cognitive domains most likely to be affected in MS are information processing speed and memory. Visual processing and executive function are less likely to be impaired, while language is largely intact. The profile is opposite to that usually seen in Alzheimer’s disease and, because language capability is mostly intact, diagnosis can be problematic. Cognition is affected by other MS symptoms such as fatigue and depression, although the link between objective measures and self-report is complex and unreliable for both symptoms [1]. Of current interest in this field is the relationship between intellectual enrichment (usually assessed by educational attainment) and cognitive reserve. It has been shown that people with lower cognitive reserve for specified disease burden, atrophy or lesions will lose more cognitive performance compared with people with the same level of disease burden, atrophy or lesions but with higher cognitive reserve [4]. Assessment of cognitive function in MS has traditionally been unavailable for patients outside specialist centers. This is partly because cognitive assessment requires specialist skills, can be time consuming to administer and the materials and validated measures have not been widely available in many countries. The Multiple Sclerosis Neuropsychological Questionnaire (MSNQ) is a selfreported screening questionnaire that predicts neuropsychological deficiency with good sensitivity and specificity, but is confounded by depression [5]. Other tests such as the Brief Battery and the Minimal Assessment of Cognitive Function in MS (MACFIMS) are time consuming and require a specialist psychologist to complete, and are therefore not ideal for routine use. The Brief International Cognitive Assessment for MS (BICAMS [6]) initiative was designed to address these issues. An international expert consensus group was set up to develop a tool that could be used by healthcare professionals who are not cognitive specialists. BICAMS comprises a 15-min battery of tests developed from approximately 80 key scientific articles. Two commit tee members evaluated each article, and candidate scales were rated for psychometric standards (reliability, validity and sensitivity) and pragmatic standards (international applicability, ease of administration, feasibility in the specified context and acceptability to patients) [7]. A validation