A comparision of neurocognitive function among patients with bipolar depression,recurrent unipolar depression and schizophrenia

Abstract

Objectives To compare neurocognitive function in patients with bipolar depression typeⅠ (BD),recurrent unipolar depression (UD) and schizophrenia (SZ).And try to explore the relationship between neuropsychological function and clinical features in bipolar. Methods 29 patients with BD,25 with UD,30 with SZ were consecutively recruited from clinics and wards of Peking University Sixth Hospital between September 2010 and April 2011,also including 30 controls from community.Four groups of participants were diagnosed by SCID-Ⅰ/P (structured clinical interview for DSM-Ⅳ-TR axisⅠdisorder-patient edition),then accepted a cross-sectional comparison targeting on performance of seven cognitive domains including sustained attention,learning,memory,motor skills,social cognition,executive functions and psychomotor speed,as well as global cognitive function.Associations between cognitive function and clinical features were examined by correlation analysis in BD. Results Compared with controls,SZ group showed severe deficit nearly in all cognitive variables (ES=-0.81--1.76),while BD and UD groups almost showed a mild to moderate deficit (ES=0.5-0.8).SZ group performed significantly worse than BD group in sustained attention (40.4±7.9 vs.49.8±7.4,P=0.001),learning (37.8±10.7 vs.47.1±10.1,P=0.007),memory (40.6±11.9 vs.48.6±9.3,P=0.035),executive function (40.5±7.1 vs.45.9±5.2,P=0.006),processing speed (33.4±9.2 vs.41.7±6.0,P 0.05),except UD performed worse than BD in executive planning task (40.1±9.04 vs.46.0±10.7,P=0.030).Negative association exited between cognitive variables and depression severity,course of illness,number of hospitalizations due to mental illness,especially for verbal learning and memory (P<0.05). Conclusions Patterns and severity of neurocognitive deficits in BD and SZ are possibly different,while similar impaired pattern exists in BD and UD.Neurocognitive deficit play a role in differentiating BD from SZ,but not an sufficient indicators to distinguish between BD and UD.Negative association exits between cognitive performance and clinical features in BD,especially for verbal learning and memory. Key words: Bipolar disorder; Schizophrenia; Cognition