The role of cognitive impairment in psychosocial functioning in remitted depression

Highlights

• Executive functioning is the cognitive domain most strongly associated with overall psychosocial functioning in remitted MDD

• Executive functioning in remitted MDD contributes to subdomains of occupational functioning, subjective cognition, and leisure time

• In mentally healthy individuals, cognitive predictors of functioning include executive functioning, attention, and semantic fluency

Abstract

Background

Cognitive dysfunction is a prevalent and disabling symptom of Major Depressive Disorder (MDD), and is often retained in the remitted stage of illness. Emerging evidence suggests that cognitive impairment may be associated with dysfunction in a number of psychosocial domains (e.g., workplace productivity, social relationships). The current study explored the relationship between cognition and psychosocial functioning in remitted MDD and in healthy controls.

Methods

Data were obtained from 182 participants of the Cognitive Function and Mood Study (CoFaM-S), a cross-sectional study of cognition, mood, and social cognition in mood disorders. Participants’ (Remitted MDD n = 72, Healthy n = 110) cognition was assessed with a battery of cognitive tests including the Repeatable Battery for the Assessment of Neuropsychological Function (RBANS) and other standard measures of cognition (e.g., The Tower of London task). Psychosocial functioning was clinically evaluated with the Functioning Assessment Short Test (FAST).

Results

The results indicated that executive functioning was the strongest independent predictor of functioning in remitted MDD patients, whereas various cognitive domains predicted psychosocial functioning in healthy individuals.

Limitations

Psychosocial functioning was measured with a clinical interview, and was therefore reliant on clinicians' judgement of impairment, as opposed to more objective measures of functioning.

Conclusions

These findings suggest that executive cognition plays an important role in functional recovery in remitted depression, and may be a crucial target in adjunctive treatment.

Introduction

Major Depression is the most common mental illness worldwide, affecting approximately 322 million individuals (Buist-Bouwman et al., 2008). While the illness is characterised by negative mood, impaired cognition is now acknowledged as a common symptom of MDD (Baune et al., 2010, Motter et al., 2016, Weightman et al., 2014). Cognitive deficits are often retained despite improvement, and even remittance, of mood symptoms (Knight and Baune, 2018, McIntyre and Lee, 2016), suggesting that cognitive dysfunction in MDD occurs independently of other symptoms (Baune et al., 2010, Bortolato et al., 2014, McIntyre et al., 2015a, Miller et al., 1998). It is possible that cognitive symptoms are often maintained because current treatments (e.g., SSRIs, CBT) focus primarily on improving mood and remediating negative behavioural patterns, and do not sufficiently address cognitive issues (Cambridge et al., 2018, McIntyre et al., 2013). Recent studies suggest that maintenance of cognitive dysfunction in the remitted stage presents a barrier to functional recovery in a number of domains (e.g., occupational functioning, autonomy) (Evans et al., 2014, Weightman et al., 2014). In turn, psychosocial deficits are associated with MDD relapse and a poor long-term course of recovery (Bortolato et al., 2014, Miller et al., 1998), underscoring the need for more research on this topic.

Recent reviews of cognitive dysfunction in currently depressed individuals suggest that executive functioning, working memory, and attention are the most commonly affected domains (Bortolato et al., 2014, Cambridge et al., 2018, Mondal et al., 2007), with deficits observed in the magnitude of 1–2 standard deviations below the norm (Bortolato et al., 2014). Although more research is needed to identify which of these cognitive deficits are retained in the remitted stage (Hasselbalch et al., 2011), the available studies suggest that executive functioning and attention remained impaired (Hasselbalch et al., 2011, Paelecke-Habermann et al., 2005). Executive functioning is crucial to maintaining adaptive performance in a number of day-to-day tasks, including decision making organisation and learning (Harvey et al., 2004, Morris and Jones, 1990). Likewise, the ability to sustain attention and switch attention in tasks is in high demand in everyday life and modern occupational environments (McIntyre and Lee, 2016). Given the broad application of the domains affected by MDD, it is not surprising that a number of recent studies have identified cognitive issues as a mediator of poor psychosocial functioning in MDD (Brewster et al., 2017, Graziane et al., 2016, Jaeger et al., 2006, McIntyre et al., 2017). Although existing evidence supports the notion that cognition is related to functioning in MDD in general, there is a noted lack of clarity regarding the domain-specific nature of this relationship (Cambridge et al., 2018, Evans et al., 2014), which is addressed by the current research.

While there is not yet consensus regarding the psychosocial domains of primarily affected by cognitive issues, functional deficits are frequently reported in domains of employment status, occupational productivity, interpersonal relationships, autonomy, and global functioning (Bortolato et al., 2014, Cambridge et al., 2018, Evans et al., 2014, McIntyre and Lee, 2016). Functional issues account for a large degree of the societal and economic burden of MDD, with billions of dollars lost to work absences and unproductive work time (McIntyre et al., 2015b, Mintz et al., 1992). Returning to work, maintaining productivity and general daily functioning may therefore be reliant on remediation of underlying cognitive deficits (Ikebuchi et al., 2017, McIntyre et al., 2015a).

While cognitive issues appear to affect functioning independently of mood symptoms, some studies have also identified an interaction between cognition and depression severity on functional outcomes (Kiosses and Alexopoulos, 2005, Kiosses et al., 2001, Paelecke-Habermann et al., 2005). Specifically, cognitive dysfunction appears to increase the negative effect of depression severity on functional outcomes, such that those with cognitive issues and severe depression suffer worse long-term functional outcomes than those with severe depression alone (Kiosses and Alexopoulos, 2005, Kiosses et al., 2001, Paelecke-Habermann et al., 2005). The primary role of cognition and psychosocial functioning in maintaining mental health underscores the need for more research in this domain (Hasselbalch et al., 2011, Paelecke-Habermann et al., 2005). In particular, there is a clear need to determine which domains of cognition are the strongest predictors of functional outcomes in the remitted stage of illness. Elucidating domain-specific relationships is necessary to both improve existing cognitive treatment, and to develop adjunctive treatments designed specifically to remediate cognitive issues related to psychosocial functioning (Knight and Baune, 2017, Motter et al., 2016), which may be the strongest predictor of long term mental health (Mintz et al., 1992, Romera et al., 2011). To determine which issues are specific to the remitted stage, it is important to also examine the relationship between cognition and functioning in a healthy group. This comparison will enable detection of the cognitive domains presenting a barrier to functional recovery in MDD, as opposed to being associated with functioning in general.

The present article investigated the link between objective cognitive performance and psychosocial functioning in remitted and healthy individuals. The primary aims of the study were:

• To determine whether domain-specific cognitive abilities (e.g., executive functioning, attention) predicted overall psychosocial functioning (i.e., total score in the Functioning Assessment Short Test (FAST)) and subdomains of functioning (e.g., occupational functioning) in individuals with remitted MDD.

• To investigate whether the relationship between cognition and functioning differed between the remitted and healthy groups.