Cognitive dysfunction in adult patients with neuromyelitis optica: a systematic review and meta-analysis

The objective of this study was to investigate cognitive dysfunction in 24-60-year-old neuromyelitis optica (NMO) patients, demographically matched healthy subjects, and MS patients. We conducted a comprehensive literature review of the PubMed, Medline, EMBASE, CNKI, Wan Fang Date, Web of Science, and Cochrane Library databases from inception to May 2016 for case-control studies that reported cognitive test scores in NMO patients, healthy subjects, and MS patients. Outcome measures were cognitive function evaluations, including performance on attention, language, memory, information processing speed, and executive function tests. The meta-analysis included eight studies. NMO patients performed significantly worse on attention (P < 0.00001), language (P = 0.00008), memory (P = 0.00004), information processing speed (P < 0.00001), and executive function tests (P = 0.00009) than healthy subjects. There were no significant differences in performance between NMO patients and MS patients on these tests. This meta-analysis indicates that NMO patients aged 24-60 years have significantly worse cognitive performance than demographically matched healthy subjects. However, this was comparable to the performance of demographically matched MS patients. There is a need for further rigorous randomized controlled trials with focus on elucidating the underlying mechanism of cognitive dysfunction in NMO patients.