Multiple Sclerosis (MS) is one of the most common chronic diseases of the central nervous system, and in New Zealand an estimated 4000 people are currently affected. This study was conducted to examine executive functioning, memory and general ability in a community-based sample of 95 participants with MS. The sample included those with relapsing-remitting, secondary progressive, chronic progressive and benign MS with an average duration of illness of 11.8 years. Only 9% of the participants showed no indication of cognitive impairment with most exhibiting mild executive dysfunction across the range of shifting, inhibition, fluency and working memory categories. As this became more widespread, all other measures of cognitive ability and memory also showed evidence of deterioration, but in some, this may have been due to slowed information processing. Overall, there was a high degree of variability in the levels of performance and there was no 'typical' pattern of deficits associated with MS. Thus, a proportion of those living with MS may have to cope with noticeable and unpredictable cognitive decline in addition to their physical disabilities.

Slowed information processing speed (IPS) is frequently reported in those with multiple sclerosis (MS), and at least 20% are compromised on some aspect of executive functioning also. However, any relationship between these two processes has not been examined. The Sternberg Memory Scanning Test, Processing Speed Index (WAIS-III), Delis Kaplan Executive Function System (D.KEFS), and Working Memory Index (WMS-III) were administered to 90 participants with MS. Their performance on the PSI was significantly below the normative scores but no deficits in memory scanning speed were evident. The initial response speed of the Sternberg and the PSI were more closely related to D.KEFS performance, particularly in timed tasks with a high cognitive demand (switching tasks). In contrast, memory scanning speed was related to working memory. This study reinforces the link between IPS and working memory in MS, and supports the suggestion that IPS is not a unitary construct.

No abstract