About 3% of the working-age population experience an episode of depressive disorder each year. Due to recall problems, the estimate of first-time incidence may be too high.

Background Anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis is a severe autoimmune condition, which typically affects young females. The long-term clinical consequences and brain morphology changes after anti-NMDAR encephalitis are not well known. Case presentation We present clinical and neuroimaging follow-up data on a 25-year female patient with typically presenting anti-NMDAR encephalitis. Longitudinal analyses of brain morphology were done using 3 T structural magnetic resonance imaging (sMRI) and Freesurfer analysis at the time of diagnosis and after symptomatic remission. The presented case attained good functional recovery after standard immunoglobulin-corticosteroid treatment but elevated serum NMDAR antibody levels persisted. The patient had no symptomatic relapses during a 3-year clinical follow-up. In the baseline brain sMRI scan there were no marked volume changes. However, a follow-up sMRI after 9 months indicated clear volume reductions in frontal cortical regions compared to matched controls with identical sMRI scans. Conclusions This case report of anti-NMDAR encephalitis suggests that despite clinical recovery long-term brain morphological changes can develop in the frontal cortex. Longer clinical and imaging follow-up studies are needed to see whether these frontocortical alterations are fully reversible and if not, can they result in trait vulnerabilities for e.g. neuropsychiatric disorders. Electronic supplementary material The online version of this article (10.1186/s12888-019-2141-4) contains supplementary material, which is available to authorized users.