The model combining older age at testing, lower education level, and lower number of CD4+ T lymphocyte predicted a higher risk of cognitive impairment of ALS patients, with an area under the ROC curve value of 0.842 (95% CI 0.775–0.933, P < 0.001), a sensitivity of 90.6%, and a specificity of 67.3% (Fig. 1). Here, CD4 is linked to amyotrophic lateral sclerosis.