Prevalence, Clinical Characteristics, and Etiologies of Mental Disorders Due to Another Medical Condition at Photharam Hospital

Abstract

         Background: The diagnosis of psychiatric disorders requires careful evaluation to determine whether the psychiatric symptoms are attributable to an underlying medical condition. However, data on the prevalence of mental disorders due to another medical condition in Thailand remain limited.

         Objective: To determine the prevalence, clinical characteristics, and etiologies of mental disorders due to another medical condition and to identify factors associated with whether the underlying medical condition was diagnosed before or after the psychiatric diagnosis.

         Methods: This retrospective study retrieved the medical records of all outpatients who received a psychiatric diagnosis at Photharam Hospital between 1 January and 31 December 2024. Medical records of patients diagnosed with mental disorders due to another medical condition were subsequently reviewed, excluding those with the diagnosis of delirium or mental disorders due to psychoactive substance use.

         Results: Among 2,033 patients with any mental disorders, 52 patients were diagnosed with mental disorders due to another medical condition corresponding to a prevalence of 2.56% (95% CI, 1.92-3.34). Psychotic disorder due to another medical condition was the most common diagnosis. When comparing patients with primary psychiatric disorders and those with mental disorders due to another medical condition, the patients with bipolar disorder due to another medical condition accounted for 17.6% of patients with bipolar disorder. Among patients with mental disorder due to another medical condition, 40.4% had no prior diagnosis of the underlying medical condition. Age ≥ 60 years was independently associated with receiving a diagnosis of the underlying medical condition only after the psychiatric diagnosis. The most common underlying medical conditions were dementia, traumatic brain injury, and epilepsy.

         Conclusion: The prevalence of mental disorders due to another medical condition was 2.56% among patients with any psychiatric disorders. Given that 40.4% of patients had no prior diagnosis of the causative medical condition, clinicians should consider evaluating possible medical etiologies through comprehensive history taking, physical examination, and appropriate investigations. Older adults were more likely to be diagnosed with the underlying medical condition after presenting with psychiatric symptoms.