Cognitive Decline in Post-treatment Lyme Disease Syndrome

Patient-reported cognitive complaints are common in those with post-treatment Lyme disease syndrome (PTLDS). Objective evidence of cognitive impairment in this population is variable in part due to methodological variability in existing studies. In this study, we sought to use a systematic approach to characterizing PTLDS based on the most current consensus diagnosis. We further examined PTLDS-related cognitive decline, operationalized as a significant decline in cognitive test performance relative to premorbid cognitive ability. We enrolled a case series of 124 patients with confirmed PTLDS defined by Infectious Diseases Society of America-proposed case definition. Cognitive functioning was evaluated using standardized neuropsychological measures. The majority (92%) of participants endorsed some level of cognitive difficulty, yet 50% of the sample showed no statistically or clinically significant cognitive decline, 26% of the sample evidenced significant cognitive decline on measures of memory and variably on measures of processing speed, and 24% of the sample were excluded from analyses due to suboptimal test engagement. The current findings are consistent with the literature showing that the most robust neurocognitive deficit associated with PTLDS is in verbal memory and with variable decline in processing speed. Compared to population normative comparison standards, PTLDS-related cognitive decline remains mild. Thus, further research is needed to better understand factors related to the magnitude of subjective cognitive complaints as well as objective evidence of mild cognitive decline.