title: A meta-analysis of neuropsychological functioning in first-episode bipolar disorders.
abstract: Broad neuropsychological deficits have been consistently demonstrated in well-established bipolar disorder. The aim of the current study was to systematically review neuropsychological studies in first-episode bipolar disorders to determine the breadth, extent and predictors of cognitive dysfunction at this early stage of illness through meta-analytic procedures. Electronic databases were searched for studies published between January 1980 and December 2013. Twelve studies met eligibility criteria (N = 341, mean age = 28.2 years), and pooled effect sizes (ES) were calculated across eight cognitive domains. Moderator analyses were conducted to identify predictors of between-study heterogeneity. Controlling for known confounds, medium to large deficits (ES ≥ 0.5) in psychomotor speed, attention and working memory, and cognitive flexibility were identified, whereas smaller deficits (ES 0.20-0.49) were found in the domains of verbal learning and memory, attentional switching, and verbal fluency. A medium to large deficit in response inhibition was only detected in non-euthymic cases. Visual learning and memory functioning was not significantly worse in cases compared with controls. Overall, first-episode bipolar disorders are associated with widespread cognitive dysfunction. Since euthymia was not associated with superior cognitive performance in most domains, these results indicate that even in the earliest stages of disease, cognitive deficits are not mood-state dependent. The current findings have important implications for whether cognitive impairments represent neurodevelopmental or neurodegenerative processes. Future studies need to more clearly characterise the presence of psychotic features, and the nature and number of previous mood episodes.
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia; Department of Psychology, Macquarie University, Sydney, Australia. Electronic address: sze.lee@sydney.edu.au.
authors.forename: Rico S C
authors.initials: RS
authors.lastname: Lee
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Hermens
authors.affiliation: Academic Psychiatry, Institute of Neuroscience, Newcastle University, UK; Centre for Affective Disorders, Institute of Psychiatry, London, UK.
authors.forename: Jan
authors.initials: J
authors.lastname: Scott
authors.affiliation: Child Development Unit, The Children's Hospital at Westmead, Sydney, Australia.
authors.forename: M Antoinette
authors.initials: MA
authors.lastname: Redoblado-Hodge
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Naismith
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia.
authors.forename: Jim
authors.initials: J
authors.lastname: Lagopoulos
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia.
authors.forename: Kristi R
authors.initials: KR
authors.lastname: Griffiths
authors.affiliation: Department of Psychology, Macquarie University, Sydney, Australia.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Porter
authors.affiliation: Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, Sydney, Australia.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
mesh_terms: D000328:Adult; D000339:Affect; D001288:Attention; D001714:Bipolar Disorder / Q000523:psychology*; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D013997:Time Factors
keywords: Bipolar disorder; Cognitive deficits; Early intervention; First-episode; Meta-analysis; Neuropsychology