Does process-specific slowing account for cognitive deficits in Lyme disease?

Although several studies have suggested that cognitive slowing is a symptom in Lyme disease, it is not clear whether this slowing is general or relates to specific cognitive tasks. This study examined cognitive speed in 25 Lyme disease patients using a mental arithmetic task. These patients showed significant impairments when initiating the cognitive processes involved in counting, but performed as well as healthy participants (n = 23) when the number of counting increments increased. Lyme patients also performed a speeded perceptual-motor matching task as well as healthy participants. Lyme-related initiation speed deficits were significantly correlated with performance on standardized neuropsychological tests, including the Trail Making Test and the Digit Symbol Test, but not with self-reported depression. These results suggest that the cognitive deficits seen on speeded tasks are process specific in the Lyme patient group, and are not the result of generalized slowing.