Cognitive impairment in first-episode mania: a systematic review of the evidence in the acute and remission phases of the illness
Daglas et al. International Journal of Bipolar Disorders
Cognitive impairment in first-episode mania: a systematic review of the evidence in the acute and remission phases of the illness
Rothanthi Daglas 0 1
Murat Ycel
Sue Cotton 0 1
Kelly Allott 0 1
Sarah Hetrick 0 1
Michael Berk 0 1
0 Centre for Youth Mental Health, The University of Melbourne , 35 Poplar Road, Parkville, VIC 3052 , Australia
1 Orygen, The National Centre of Excellence in Youth Mental Health , 35 Poplar Road, Parkville, VIC 3052 , Australia
There is evidence of cognitive impairment that persists in the remission phase of bipolar disorder; however, the extent of the deficits that occur from the first onset of the disorder remains unclear. This is the first systematic review on cognitive functioning in the early stages of bipolar I disorder. The aim of the study was to identify the patterns and degree of cognitive impairment that exists from first-episode mania. Three electronic databases (MEDLINE, PsycINFO and PubMed) were systematically searched for studies published from January 1980 to June 2014. Eligible studies were separated into two groups: acute and remission. The Newcastle-Ottawa quality assessment scale was utilised to measure the quality of the included studies. A total of seven studies (three acute and four remission), including 230 first-episode mania and 345 healthy control participants, were eligible for the review. The studies in the acute phase only examined aspects of executive functioning, with impairments identified in cognitive flexibility, though not in response inhibition and verbal fluency relative to healthy controls. The most consistent finding during the remission phase was a deficit in working memory, whereas in the other domains, the findings were equivocal. Non-verbal memory and verbal fluency were not impacted in remission from first-episode mania. In conclusion, deficits are present in some but not all areas of cognitive functioning during the early stages of bipolar I disorder. Further research is warranted to understand the longitudinal trajectory of change from first-episode mania.
Mania; Cognition; Bipolar disorder; Depression; First episode; Early intervention
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Review
Introduction
The presence and impact of cognitive changes in bipolar
disorder has more recently been widely appreciated.
Indeed, the presence of cognitive dysfunction is
particularly noteworthy given the evidence that many people
with bipolar disorder start out cognitively intact or with
even superior cognitive functioning (MacCabe et al.
2010). There remains an ongoing debate on the timing,
pattern and significance of these changes, including
whether cognitive impairments in bipolar disorder are
state-dependent or trait markers of the illness.
There is substantial evidence of cognitive impairments
in people who are in remission from acute episodes of
bipolar disorder, supporting that euthymia may not be a
period of complete recovery (Clark et al. 2002; Quraishi
and Frangou 2002; Latalova et al. 2011; Malhi et al.
2007; Martinez-Aran et al. 2004; Lewandowski et al.
2011). More specifically, several meta-analyses
comparing euthymic patients to healthy control (HC)
participants have confirmed significant differences of medium
to large effect in tasks involving
processing/psychomotor speed, attention, sustained attention, verbal
learning and memory, visual memory and executive
functions such as: set shifting, response inhibition,
verbal fluency and working memory (Arts et al. 2008; Bora
et al. 2009; Mann-Wrobel et al. 2011; Bourne et al.
2013; Robinson et al. 2006; Torres et al. 2007).
These findings are in contrast to reports suggesting
that asymptomatic people who subsequently will
develop bipolar disorder may show minimal or no
cognitive deficits prior to illness onset (MacCabe et al. 2010).
Berk et al. (2007a) modified the staging model for
bipolar disorder, identifying an opportunity for early
intervention with the potential that early use of pharmacological
treatments such as lithium carbonate may have
neuroprotective properties (Swann et al. 1999; Franchini et al. 1999).
However, the majority of research on cognition in bipolar
disorder has been conducted on the later stages, and whilst
cognitive impairments appear to worsen with illness
progression (Robinson and Ferrier 2006), the extent and
pattern of cognitive dysfunction in the early stages remain
largely unknown.
First-episode mania (FEM) is a crucial time for the
trajectory of cognitive change. Hence, identifying
cognitive deficits that may be present prior to the effects of
multiple episodes and prolonged exposure to
psychotropic treatment is theoretically important, whilst also
informing approaches to early intervention (Berk et al.
2010). To date, there has only been one meta-analysis
on cognitive functioning in first-episode bipolar
disorder, with the findings of deficits ranging from small to
large effect for processing speed, attention, verbal
learning and memor (...truncated)