A Systematic Review of Neurocognitive Functioning in Behçet's Disease

Behçet's disease (BD) is a vascular, inflammatory multisystem disorder with neuro-Behçet's (NBD) diagnosed in a subset of patients with neurological manifestations. The objective of this review was to determine whether neurocognitive dysfunction is observed in BD, in which neurocognitive domains, and whether there are differences in rates of dysfunction observed between BD and NBD groups. Studies of any methodology were included that reported results from standardized neurocognitive assessment measures in participants with BD or NBD. Twelve group comparison studies met the criteria for inclusion in the review (totalling 284 BD and 157 NBD participants), as well as 17 case study/series papers (11 BD, 35 NBD). Issues with blinding, incomplete data reporting and selective reporting bias were found across the group and case study/series papers, as well as inadequate statistical adjustment for multiple comparisons in the group studies, and the lack of the use of appropriate norms or adjustment for premorbid ability in the case series/studies papers. These quality issues impacted on the conclusions that could be drawn from the current literature. Neurocognitive dysfunction was found in NBD compared to health controls (HC) in a higher proportion of results across studies, than in comparisons between BD and HC groups. The domains in which neurocognitive attenuation was most often reported were visual spatial ability, working memory and acquired knowledge, with more than 25% of these results showing significantly lower functioning in both the BD and NBD groups compared to HC. More than 25% of the processing speed and long-term memory encoding and retrieval results were also lower for the NBD group, compared to HC. Group comparisons between NBD and multiple sclerosis participants indicated few significant differences in neurocognitive test results. The majority of case study/series participants were found to have some degree of attenuated neurocognitive functioning, as defined by case study/series authors.