Enhancing identification of nonaffective psychosis in register-based studies.

The Finnish Quality of Psychosis Care Register assesses nonaffective psychosis (NAP) care, acknowledging treatment outside specialized psychiatric services. This approach, while providing a holistic view, raises concerns about diagnostic inaccuracies. Here, we studied situations where the register-based diagnosis might be inaccurate, and whether the first episode can be reliably identified using a 14-year wash-out period. People with first register-based NAP (ICD-10 F20-F29) between years 2010 and 2018 and without NAP diagnoses in 1996-2009 were identified from the Care Register for Health Care. A diagnosis of NAP was deemed unreliable before age 7, when dementia preceded NAP diagnosis, and when a NAP diagnosis had been assigned at admission or during psychiatric hospitalization but was not confirmed by discharge diagnosis. Despite a 14-year follow-back the first register diagnosis may miss the first treatment episode in older patients. Register-based studies on psychotic disorders should pay attention to exclusion criteria and to the definition of treatment onset.

Theory of mind in a first-episode psychosis population using the Hinting Task.

Deficiencies in theory of mind (ToM) are common in psychosis and may largely explain impaired social functioning. Currently, it is unclear whether impairments in ToM are explained by the more general cognitive deficits related to psychosis or whether ToM is impaired in psychosis independently of other cognitive deficits. This study examined ToM using the Hinting Task in young adults (n = 66) with first-episode psychosis and matched controls (n = 62). The participants were administered a broad neuropsychological assessment. Participants with psychosis performed worse than controls on the Hinting Task. However, 75% of the variance between the groups was explained by general cognitive deficits, especially impaired processing speed and episodic memory. Hinting Task performance of the best functioning patient group did not differ from that of the control group. When the psychosis group was divided according to diagnosis, the Hinting Task difference between individuals with schizophrenia and controls remained significant even when general cognitive performance was controlled for, suggesting specific verbal ToM deficits in schizophrenia. In contrast, those with other psychotic disorders did not differ from controls. Our results suggest that ToM deficits can be seen in early phases of psychotic disorders, schizophrenia in particular, and are partly independent of other cognitive functions.