European neuroborreliosis: neuropsychological findings 30 months post-treatment

Background: The aim of this study was to compare neuropsychological (NP) functioning in patients with Lyme neuroborreliosis (LNB) 30 months after treatment to matched controls. Methods: We tested 50 patients with LNB and 50 controls with the trail-making test (TMT), Stroop test, digit symbol test, and California Verbal Learning test (CVLT). A global NP sumscore was calculated to express the number of low scores on 23 NP subtasks. Results: Mean scores were lower amongst LNB-treated patients than amongst controls on tasks assessing attention/executive functions: (Stroop test 4: 77.6 vs. 67.0, P = 0.015), response/processing speed (TMT 5: 23.4 vs. 19.2, P = 0.004), visual memory (digit symbol recall: 6.6 vs. 7.2, P = 0.038), and verbal memory (CVLT list B: 4.68 vs. 5.50, P = 0.003). The proportion of patients and controls with NP sumscores within one SD from the mean in the control group (defined as normal) and between one and two SD (defined as deficit) were similar, but more LNB-treated patients than controls had a sumscore more than two SD from the mean (defined as impairment) (8 vs. 1, P = 0.014). Conclusions: As a group, LNB-treated patients scored lower on four NP subtasks assessing processing speed, visual and verbal memory, and executive/attention functions, as compared to matched controls. The distribution of NP dysfunctions indicates that most LNB-treated patients perform comparable to controls, whilst a small subgroup have a debilitating long-term course with cognitive problems.