The association between schizophrenia spectrum disorders and psoriasis: a large‐scale population‐based case‐control study

Psoriasis (PsO), an immune‐mediated disorder, affects approximately 2‐3% of the North American population, while up to a third of patients with PsO may develop psoriatic arthritis (PsA). Both PsO and PsA have been associated with schizophrenia spectrum disorders (SSDs). For instance, a recent meta‐analysis (MA) suggests that individuals with schizophrenia (SCZ) may carry a higher risk of developing PsO. However, those findings challenge previous case‐control studies in which no associations were found between PsO and SCZ, and thus, it remains unclear whether SSDs are associated with an increased risk of PsO and PsA. Furthermore, observational studies may present biases (e.g., reverse causation and confounding), and hence the association between SSD and PsO and PsA deserve replication in well‐designed, population‐based, large‐scale studies.