Cognition in the early stage of multiple sclerosis.

OBJECTIVE: Cognitive dysfunctions may contribute to limitation of everyday activities of patients with multiple sclerosis (MS). Recent studies have demonstrated that 45 to 65% of MS-patients are cognitively impaired. The profile of MS-related cognitive dysfunctions varies greatly. It includes memory and learning deficits, attention deficits, executive dysfunctions and visuo-spatial deficits. Most studies of cognition in MS examined patients in later stages, often including MS-patients with marked physical disabilities. Studies of cognitive dysfunctions in the early stage of the disease are rare. This study specifically aimed at evaluating and characterizing cognitive impairments in the early stage of MS, and determining specific patterns of cognitive dysfunction.

METHODS: 21 MS patients, experiencing their first neurological symptoms not more than two years previously, and 22 healthy controls were compared. A comprehensive neuropsychological test-battery was used to evaluate MS-related cognition. The battery consisted of memory and learning tests, executive functioning tests and a visuo spatial functioning test. A computerized attention test-battery was also included, which assess accuracy and speed of test responses. In addition depression and intellectual capabilities were assessed.

RESULTS: Compared with healthy controls, MS-patients in the early stage of the disease performed significantly lower on each neuropsychological assessment, except for verbal short-term memory. In particular, MS-patients showed a lengthened reaction time for simple and focused attention (19-38%), impaired non-verbal memory function (RVDLT recognition: 33%) and a planning deficit (24%). Associations between information processing speed and disease course and the employment situation were additionally found. However, patients did not have clinically relevant depression rates on the ADS-L and visuo spatial abilities remain preserved.

CONCLUSION: Our findings revealed discrete cognitive dysfunction in MS-patients within the early stage of the disease.