The prevalence of medical illnesses is high among patients with psychiatric disorders. The current study aimed to investigate multi-comorbidity in patients with psychiatric disorders in comparison to the general population. Secondary aims were to investigate factors associated with metabolic syndrome and treatment appropriateness of mental disorders.

The sample included 54,826 subjects (64.73% females; 34.15% males; 1.11% nonbinary gender) from 40 countries (COMET-G study). The analysis was based on the registration of previous history that could serve as a fair approximation for the lifetime prevalence of various medical conditions.

About 24.5% reported a history of somatic and 26.14% of mental disorders. Mental disorders were by far the most prevalent group of medical conditions. Comorbidity of any somatic with any mental disorder was reported by 8.21%. One-third to almost two-thirds of somatic patients were also suffering from a mental disorder depending on the severity and multicomorbidity. Bipolar and psychotic patients and to a lesser extent depressives, manifested an earlier (15–20 years) manifestation of somatic multicomorbidity, severe disability, and probably earlier death. The overwhelming majority of patients with mental disorders were not receiving treatment or were being treated in a way that was not recommended. Antipsychotics and antidepressants were not related to the development of metabolic syndrome.

The finding that one-third to almost two-thirds of somatic patients also suffered from a mental disorder strongly suggests that psychiatry is the field with the most trans-specialty and interdisciplinary value and application points to the importance of teaching psychiatry and mental health in medical schools and also to the need for more technocratically oriented training of psychiatric residents.

Patients with anti-N-methyl-d-aspartate (NMDA) receptor encephalitis (ANMDARE) show a wide range of behavioral abnormalities and are often mistaken for primary psychiatric presentations. We aimed to determine the behavioral hallmarks of ANMDARE with the use of systematic neuropsychiatric and cognitive assessments.

A prospective study was conducted, with 160 patients admitted to the National Institute of Neurology and Neurosurgery of Mexico, who fulfilled criteria for possible autoimmune encephalitis and/or red flags along a time window of seven years. Cerebrospinal fluid (CSF) antibodies against the NR1 subunit of the NMDAR were processed with rat brain immunohistochemistry and cell-based assays with NMDA expressing cells. Systematic cognitive, neuropsychiatric, and functional assessments were conducted before knowing NMDAR antibodies results. A multivariate analysis was used to compare patients with and without definite ANMDARE according to antibodies in CSF.

After obtaining the CSF antibodies results in 160 consecutive cases, 100 patients were positive and classified as having definite ANMDARE. The most frequent neuropsychiatric patterns were psychosis (81%), delirium (75%), catatonia (69%), anxiety-depression (65%), and mania (27%). Cognition was significantly impaired. A total of 34% of the patients had a predominantly neuropsychiatric presentation without seizures. After multivariate analysis, the clinical hallmarks of ANMDARE consisted of a catatonia–delirium comorbidity, tonic-clonic seizures, and orolingual dyskinesia.

Our study supports the notion of a neurobehavioral phenotype of ANMDARE characterized by a fluctuating course with psychotic and affective symptoms, catatonic signs, and global cognitive dysfunction, often accompanied by seizures and dyskinesia. The catatonia–delirium comorbidity could be a distinctive neurobehavioral phenotype of ANMDARE.