Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory and autoimmune disorder of the central nervous system characterized by optic neuritis and longitudinally extensive transverse myelitis as core symptoms. Additionally, area postrema syndrome and brain stem syndrome are also common, as well as the presence of serum autoantibodies that act on the aquaporin-4 (AQP4-immunoglobulin G (AQP4-IgG)) water channels in approximately 80 % of cases (Jarius et al., 2008; Lennon et al., 2004; Wingerchuk et al., 2015)). NMOSD represents a major cause of neurological disability in adults which significantly affects the daily life of patients. It is more frequent in women, with ratios of 5:1 to 10:1. NMOSD has an average age of onset of 30–40 years and people of Hispanic, African, Asian, and Native American descent are more susceptible to it (Flanagan and Weinshenker, 2014). In Mexico, a prevalence of 1 per 100,000 inhabitants has been estimated, which represents 16 % of all autoimmune diseases of the central nervous system in that country (Rivera et al., 2008; Velazquez et al., 2023).

Recently, NMOSD has been associated to cognitive impairment, although the reports are still scarce and the results regarding the neuropsychological profile in these patients have been variable (Eizaguirre et al., 2017; Moore et al., 2016; Saji et al., 2013; Vanotti et al., 2013). Although cognitive impairment in NMOSD occurs in up to 70 % of patients, it has received little recognition (Oertel et al., 2019). Importantly, the neuropsychological batteries used for its study vary across studies, making comparisons challenging. Nevertheless, impairments in attention, memory, executive processes, and processing speed have been frequently reported (Blanc et al., 2008; Meng et al., 2017; Saji et al., 2013). Cognitive impairment in NMOSD has been identified as a determining factor in patients' quality of life, along with fatigue and depression (He et al., 2011). However, it is unclear whether cognitive changes are related to the expression of AQP4-IgG antibodies, the degree of lesions in the central nervous system, and/or the degree of functional disability (Blanc et al., 2008; Eizaguirre et al., 2017; Saji et al., 2013; Vanotti et al., 2013), especially at early and middle stages of the disease, which was our objective. Likewise, not enough research has been conducted on cognitive impairment in latin american (much less Mexican) persons suffering from NMOSD.