Which diagnoses and arguments regarding severe mental disorder do forensic psychiatric experts in Sweden consider in different cases? A qualitative vignette study

The decision-making process of experts in forensic psychiatric investigations (FPI) is complex and reasoning regarding psychiatric diagnosis and severe mental disorder (SMD, the judicial concept central to legal exemption in Swedish law) has severe ramifications. Nevertheless, the qualitative aspects of FPI experts' decision-making process have seldom been studied systematically. Method. The participants (N = 41) were FPI experts: forensic psychiatrists (n = 15), forensic psychologists (n = 15) and forensic social workers (n = 11). Using three case vignettes and qualitative content analysis, it was explored how case-specific characteristics could affect which hypotheses FPI experts generated regarding a) psychiatric diagnosis and b) severe mental disorder and c) which information sources they required. Each case vignette described a diagnostically ambiguous case but indicated emphasis on: psychotic symptoms (case 1); personality disorder symptoms (case 2) and neurodevelopmental disorder symptoms (case 3). Results. Experts reasoned in a similar manner regarding generating hypotheses and required information, but also in a case-adapted manner. Experts considered various diagnostic alternatives, and some (e.g. psychosis) were mentioned for all three cases. Other diagnoses were only suggested as hypotheses in certain cases (e.g. case 3: intellectual disability). Discussion. In Sweden, a core basis for SMD is psychotic-like functioning, and psychosis was suggested as a hypothesis for all three cases. Experts reasoned in similar ways regarding SMD in all cases, considering various perspectives for and against SMD. Some case-specific arguments for and against SMD adapted to the psychopathological circumstances were found. These could be related to aspects of the SMD concept that become important to ascertain when the type of psychopathology indicated in the case vignette was present; for example, ascertaining reality monitoring for a person with potential delusions of being followed by a criminal gang requires investigation of criminal history and related conflicts. Taken together, FPI-experts considered a broad range of psychiatric diagnoses in various cases. Their reasoning regarding SMD was both based on general and case-specific (or psychopathology-specific) factors.