1 Psykiatrisk Center Glostrup, Mental Health Services, The Capital Region of Denmark2 Børne- & Ungdomspsykiatrisk Center Bispebjerg, Børne- og Ungdomspsykiatrisk Center, Region Hovedstaden, Mental Health Services, The Capital Region of Denmark3 Børne- og Ungdomspsykiatrisk Center, Region Hovedstaden, Mental Health Services, The Capital Region of Denmark4 Clinical Intervention and Neuropsychiatric Schizophrenia Research/Center for Neuropsykiatrisk Skizofreniforskning, Psykiatrisk Center Glostrup, Mental Health Services, The Capital Region of Denmark5 Anæstesi- og operationsklinikken HOC, HovedOrtoCentret Rigshospitalet, Rigshospitalet, The Capital Region of Denmark6 unknown
BACKGROUND: Impaired cognition is a prominent feature of schizophrenia. To what extent the heterogeneous cognitive impairments can be accounted for by considering only a single underlying impairment or a small number of core impairments remains elusive. This study examined whether cognitive impairments in antipsychotic-naïve, first-episode schizophrenia patients may be determined by a relative slower speed of information processing. METHOD: Forty-eight antipsychotic-naïve patients with first-episode schizophrenia and 48 matched healthy controls were administered a comprehensive battery of neuropsychological tests to assess domains of cognitive impairments in schizophrenia. Composite scores were calculated, grouping tests into cognitive domains. RESULTS: There were significant differences between patients and healthy controls on global cognition and all cognitive domains, including verbal intelligence, processing speed, sustained attention, working memory, reasoning and problem solving, verbal learning and memory, visual learning and memory, and reaction time. All these significant differences, except for verbal intelligence and global cognition, disappeared when processing speed was included as a covariate. CONCLUSION: At the first stage of illness, antipsychotic-naïve patients with schizophrenia display moderate/severe impairments in all the cognitive domains assessed. The results support the contention of a global cognitive dysfunction in schizophrenia that to some extent may be determined by impaired processing speed.