Cognitive impairment and multiparametric brain MRI in aquaporin-4-IgG positive neuromyelitis optica spectrum disorder.

BACKGROUND

Cognitive impairment (CI) in neuromyelitis optica spectrum disorder (NMOSD) remains poorly understood.

OBJECTIVES

To investigate the prevalence of CI and its association with diffuse brain tissue integrity, assessed by multiparametric brain MRI, in NMOSD.

METHODS

This cross-sectional study included 99 participants: 57 anti-aquaporin-4 positive NMOSD patients and 42 age-, sex-, and education-matched healthy controls (HC). All participants underwent neuropsychological testing and multimodal brain MRI. Patients were classified as CI if they scored ≤ -1.5 z-score in at least one test in two or more cognitive domains. Global and regional brain volume fractions and the mean values for the T1/T2-weighted ratio, magnetization transfer ratio, fractional anisotropy, and diffusivity metrics were analyzed in normal-appearing white and gray matter. After conducting univariable analyses to compare clinical, neuropsychological, and MRI metrics between groups (NMOSD vs. HC or NMOSD with vs. without CI), we performed ordinal logistic regression using MRI metrics to predict cognitive outcomes.

RESULTS

Thirty-two percent of the NMOSD patients showed CI, with attention/processing speed and executive function being the most affected domains. NMOSD and HC were similar in most MRI metrics (p > 0.05), as were the CI and cognitively preserved NMOSD subgroups (p > 0.05). Lower brain parenchymal and gray matter (GM) fractions predicted worse Stroop test performance (OR = 0.38; p = 0.013; OR = 0.44; p = 0.043). Most diffuse microstructural MRI metrics did not predict CI.

CONCLUSIONS

One-third of NMOSD patients exhibited CI. Notably, multiparametric brain MRI revealed preserved diffuse microstructural integrity in NMOSD patients, including CI patients. While most MRI metrics did not predict cognitive impairment, GM atrophy was associated with executive dysfunction.