A 46-year-old man has suspected colleagues for years, but his beliefs remain recognisable as exaggerated distrust rather than fixed false convictions, and he functions reasonably when reassured. His brother has a fixed, non-bizarre, unshakeable belief over two years that neighbours are pumping gas into his house, with no other psychopathology. The brother's condition is best classified as:

• A Schizotypal personality disorder
• B Paranoid personality disorder
• C Schizophrenia, paranoid subtype
• D Delusional disorder, persecutory type ✓

Explanation

The brother has a fixed, unshakeable, non-bizarre persecutory delusion lasting over one month without hallucinations, disorganisation, or negative symptoms, which defines delusional disorder of the persecutory type. Paranoid personality disorder involves suspiciousness and mistrust that remain as attitudes and assumptions, not full delusions, and functioning is relatively preserved. The absence of other schizophrenic symptoms excludes schizophrenia.

Reference: DSM-5, American Psychiatric Association, 2013 ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.