Internet-based cognitive testing in multiple sclerosis

Cognitive impairment in multiple sclerosis is difficult to study because of the heterogeneity and variability of this disease. The gold standard for measurement of cognitive function in multiple sclerosis is a full battery of neurocognitive tests, which is time consuming and expensive. Some cognitive tests like the PASAT, a measure of working verbal memory and processing speed, have been proposed for screening and follow-up of cognitive function in clinical trials. We studied whether we could measure cognitive function in multiple sclerosis over the Internet. For this we used the Cognitive Stability Index (CSI)trade mark, developed for persons with known or suspected primary central nervous system illness. The CSI was compared with formal neurocognitive testing (NPsych) and the PASAT in a cross-sectional study of 40 consecutive multiple sclerosis patients with subjective cognitive complaints. NPsych revealed that only 18 of the 40 patients (46%) were cognitively impaired. Although both the CSI and the PASAT were equalivalent in their specificity (86%), the CSI was significantly more sensitive than the PASAT (83% versus 28%). We conclude that the CSI, because of its availability over the Internet, has great potential as a tool for screening and follow up of cognitive function in multiple sclerosis.