Insight in nonverbal correlates of paranoid ideation can potentially help improve diagnostic procedures and guide interventions. The aim was to systematically evaluate the scientific evidence investigating nonverbal correlates of paranoid ideation.

The review follows the PRISMA guidelines. Databases PsycINFO, PubMed, Web of Science, and Cinahl were searched for studies concerning the use of standardized instruments for both verbal and nonverbal measurements of paranoid ideation in adult participants. Quality of studies was evaluated using the Effective Public Health Practice Project tool. Data were systematically extracted and summarized thematically and narratively. This review was registered with PROSPERO (CRD42022288001).

The search strategy yielded 3962 results of which 22 papers met inclusion criteria. Half (n = 11) of the included articles included patients with a diagnosis on the psychosis spectrum, the other articles (n = 11) studied healthy populations. Identified nonverbal categories were spatial behavior (n = 6), brain region activity (n = 5), visual perception (n = 5), stress physiology (n = 4), information processing (n = 3), and aggression (n = 1). Some studies investigated multiple nonverbal categories.

Evidence was strongest for spatial behavior and brain region activity as nonverbal correlates of paranoid ideation. Evidence for stress physiology, information processing, and aggression as potential nonverbal correlates was less robust, due to inconsistent findings and small numbers of publications. Using nonverbal methods to assess paranoid ideation requires more investigation and evaluation. The integration of nonverbal assessments might offer new diagnostic possibilities that move beyond traditional verbal methods.

Cognitive deficits may be characteristic for only a subgroup of first-episode psychosis (FEP) and the link with clinical and functional outcomes is less profound than previously thought. This study aimed to identify cognitive subgroups in a large sample of FEP using a clustering approach with healthy controls as a reference group, subsequently linking cognitive subgroups to clinical and functional outcomes.

204 FEP patients were included. Hierarchical cluster analysis was performed using baseline brief assessment of cognition in schizophrenia (BACS). Cognitive subgroups were compared to 40 controls and linked to longitudinal clinical and functional outcomes (PANSS, GAF, self-reported WHODAS 2.0) up to 12-month follow-up.

Three distinct cognitive clusters emerged: relative to controls, we found one cluster with preserved cognition (n = 76), one moderately impaired cluster (n = 74) and one severely impaired cluster (n = 54). Patients with severely impaired cognition had more severe clinical symptoms at baseline, 6- and 12-month follow-up as compared to patients with preserved cognition. General functioning (GAF) in the severely impaired cluster was significantly lower than in those with preserved cognition at baseline and showed trend-level effects at 6- and 12-month follow-up. No significant differences in self-reported functional outcome (WHODAS 2.0) were present.

Current results demonstrate the existence of three distinct cognitive subgroups, corresponding with clinical outcome at baseline, 6- and 12-month follow-up. Importantly, the cognitively preserved subgroup was larger than the severely impaired group. Early identification of discrete cognitive profiles can offer valuable information about the clinical outcome but may not be relevant in predicting self-reported functional outcomes.