Transdiagnostic symptoms and the masking of neurocognitive impairment across the early stages of psychosis.

Impairments in processing speed and verbal learning are well documented in chronic schizophrenia and first episode psychosis (FEP), but the extent to which these patterns generalize to the clinical high-risk (CHR) stage remains less clear. A central interpretive challenge in CHR samples is the prominence of nonpsychotic symptoms, which often dominate clinical presentation and are associated with cognitive impairment in other populations -- raising the question of whether transdiagnostic psychopathology confounds assessment of psychosis-specific cognitive deficits or actively masks them. We tested these competing possibilities in CHR (n = 41), FEP (n = 32), and healthy control (n = 30) participants who completed clinical interviews (which differed across CHR and FEP) and standard measures of processing speed, verbal learning, and premorbid IQ. Between-group differences in neurocognition were compared across unadjusted, negative symptom-adjusted, and general (i.e., transdiagnostic) symptom-adjusted estimates; within-group analyses examined the influence of general symptom severity on the neurocognitive-negative symptom relation. Negative symptoms sharply attenuated case-control cognitive differences in both clinical groups, consistent with redundancy. General symptoms, by contrast, strengthened case-control differences, consistent with masking of unobserved cognitive impairment. Within-group associations between neurocognitive performance and negative symptoms were weaker and less consistent but largely were directionally similar. Exploratory item-level analyses suggested cognitive-negative associations were more limited in CHR than FEP, in whom they were more widespread across symptom components. These results suggest that negative and transdiagnostic symptom severity may exert opposing influences on neurocognitive performance in early psychosis, with implications for cognitive assessment and interpretation of CHR and FEP findings more broadly.