['Neuropsychological studies have extensively described the presence of cognitive dysfunction in MS patients. One possible pharmacological treatment of the impairment could be based on acetylcholinesterase inhibitors (AChEIs), which have shown efficacy in alleviating cognitive impairment in many other disorders. The findings on the efficacy of AChEI medication in MS associated cognitive symptoms are preliminary and no studies concerning cerebral acetylcholinesterase (AChE) activity in these patients have been published.', 'The objective of the study was to examine cerebral AChE activity in cognitively deteriorated MS patients. Cerebral AChE activity of 10 MS patients with secondary progressive disease and marked cognitive impairment, and 10 healthy controls, was studied with positron emission tomography using tracer (11)C-MP4A.', "The cognitive profile of the patients was assessed with CERAD (Consortium to Establish a Registry for Alzheimer's Disease).", 'No differences in cortical AChE activity between MS patients and controls were seen.'] Is cerebral acetylcholinesterase activity decreased in MS patients with cognitive impairment?