<p>Some patients with myasthenia gravis (MG) present with cognitive impairment (CI), and dysfunction of the cerebral glymphatic system (GS) is considered a key contributor. We hypothesized that dysfunction of the GS contributes to cognitive impairment in MG and aimed to identify potential neuroimaging biomarkers. This study included 41 patients with MG (29 patients without CI, 12 patients with CI) and 35 healthy controls (HC). GS function was assessed by calculating the diffusion tensor image analysis along the perivascular space (DTI-ALPS) and gBOLD-CSF coupling strength. Concurrently, neuropsychological testing (including MMSE, MoCA, CDT, etc.) was performed to examine the relationship between GS function and cognitive performance. Single factor analysis of variance and Kruskal-Wallis test were used for intergroup comparison. Spearman correlation analysis was used to observe the relationship between DTI-ALPS and gBOLD-CSF coupling and clinical scales. Compared with HC, patients with MG exhibited significantly reduced DTI-ALPS indices and gBOLD-CSF coupling strength (p &lt; 0.05). Additionally, MG patients with CI demonstrated a decrease in DTI-ALPS index compared with MG patients without CI (p &lt; 0.05). Furthermore, DTI-ALPS index demonstrated significant correlations with overall cognitive function in all participants. Patients with MG demonstrate impaired GS function, which correlates with their overall cognitive performance. These findings suggest that GS dysfunction may represent a characteristic feature of cognitive decline in MG.</p>