Multiple Sclerosis
Cognitive Impairment in Multiple Sclerosis – Recent Advances and Future Prospects
Dawn Langdon Clinical Neuropsychologist, and Reader in Neuropsychology, Royal Holloway, University of London
Abstract
Multiple sclerosis (MS) is characterised not only by physical disability but also by gradual cognitive impairment. A large proportion of patients exhibit signs of cognitive deficit that negatively affect their quality of life. Reduced processing speed is often seen with the disease and several tests have been developed to measure its severity, including the Paced Auditory Serial Addition Test (PASAT) and the Symbol Digit Modality Test (SDMT). Long-term memory function is also commonly impaired in MS and studies suggest problems in primary registration of information. Also affected are executive functions used in novel planning and problem-solving. To evaluate cognitive function, cognitive test batteries with varying effectiveness have been introduced. The correlation of cognitive performance with magnetic resonance imaging (MRI) results remains inconsistent as multiple pathologies lead to the observed impairments. Therefore, combinations of MRI data are most successful at predicting deficiencies. The efficacy of current MS treatments in terms of cognition is unclear, making their clinical evaluation a great unmet need; the same is true of universal, validated cognitive measures that can be easily administered to MS patients around the world.
Keywords Multiple sclerosis, cognitive impairment, memory loss, executive functions, cognitive test batteries, rivastigmine
Disclosure: Dawn Langdon has received research support from Bayer Schering Pharma AG/Bayer HealthCare Pharmaceuticals and honoraria from Bayer Schering Pharma AG/Bayer HealthCare Pharmaceuticals, Biogen, Hoffman La Roche, Merck-Serono, Novartis, sanofi-aventis and Serono Symposia, and has been contracted as a cognitive expert on studies for Bayer Schering Pharma and Merck-Serono. Received: 15 June 2010 Accepted: 2 July 2010 Citation: European Neurological Review, 2010;5(1):69–72 Correspondence: Dawn Langdon, Department of Psychology, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK. E:
D.Langdon@rhul.ac.uk
The Extent of Cognitive Impairment in Multiple Sclerosis
In his original characterisation of multiple sclerosis (MS), Jean Martin Charcot noted a loss of memory and reduced understanding,1
but
this wisdom was overlooked for a century. It is only since the early 1980s that cognitive impairment in MS has begun to be scientifically investigated and understood.2
In part this may be because reduced functioning in the context of complex physical disability may seem reasonably attributable to physical impairments. In addition, the typical pattern of cognitive deficits in MS, with intact language masking inefficiencies in concentration, memory and reasoning, may escape casual (or even clinical) observation.
The prevalence of cognitive impairment in large heterogeneous groups of MS patients has been demonstrated by formal psychometric assessment to be 43–70%, with the higher prevalence rates from clinic samples.3
Cognitive impairment has been reported at all stages and in all subtypes of the disease. In the comparative study by Potagas et al., the cognitive impairment prevalence rates were 27.3% in clinically isolated syndrome (CIS), 40.0% in relapsing–remitting MS (RRMS), 56.5% in primary progressive MS (PPMS) and 82.8% in secondary progressive MS (SPMS).4
has been demonstrated in benign MS.5 progress over time, but rarely in the space of a few years.6
The Impact of Cognitive Impairment in Multiple Sclerosis
Cognitive impairment has been shown to have an adverse effect on the lives of people with MS, over and above that imposed by their physical impairments. Cognitive impairment leads to reduced employment, social function,7 function,8 in driving11
progress in rehabilitation,9
physical independence, sexual everyday life activities,10
and adherence to medication.12 safety Poorer self-reported
scores on formal measures of quality of life have also been linked to cognitive status. Reduced information-processing speed has been associated with lower quality of life.13
However, in one study of patients with advanced disease, more intact autobiographical memory was associated with lower quality of life.14 This suggests that once patients enter the stage of significant physical dependence, the clear comparison with previous independence afforded by intact memory and other cognitive function results in greater awareness of the deterioration of their condition, resulting in a more negative assessment of current quality of life.
Cognitive Impairment Profile
A cognitive impairment prevalence of 45% Cognitive impairment tends to
There is increasing (but not yet universal) agreement that reduced processing speed is the fundamental cognitive deficit in MS.15 Processing speed affects the ability to maintain and manipulate information (working memory).16,17
Processing speed and working memory are the cognitive processes most likely to be affected in MS.18 © TOUCH BRIEFINGS 2010 69
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116