Cognitive Functioning in Patients with Bipolar Disorder: Association with Depressive Symptoms and Alcohol Use

Abstract

BackgroundCognitive dysfunction is clearly recognized in bipolar patients, but the degree of impairment varies due to methodological factors as well as heterogeneity in patient populations. The goal of this study was to evaluate cognitive functioning in bipolar patients and to assess its association with depressive symptoms. Post hoc the relationship with lifetime alcohol use disorder was explored.Methodology/Principal FindingsThe study included 110 bipolar patients and 75 healthy controls. Patients with severe depressive symptoms, (hypo)manic symptoms and current severe alcohol use disorder were excluded. Diagnoses were evaluated via the Mini-International Neuropsychiatric Interview. Cognitive functioning was measured in domains of psychomotor speed, speed of information processing, attentional switching, verbal memory, visual memory, executive functioning and an overall mean score. Severity of depression was assessed by the Inventory of Depressive Symptomatology-self rating. Patients were euthymic (n = 46) or with current mild (n = 38) or moderate (n = 26) depressive symptoms. Cognitive impairment was found in 26% (z-score 2 or more above reference control group for at least one domain) of patients, most prominent in executive functioning (effect size; ES 0.49) and speed of information processing (ES 0.47). Depressive symptoms were associated with dysfunction in psychomotor speed (adjusted beta 0.43; R2 7%), speed of information processing (adjusted beta 0.36; R2 20%), attentional switching (adjusted beta 0.24; R2 16%) and the mean score (adjusted beta 0.23; R2 24%), but not with verbal and visual memory and executive functioning. Depressive symptoms explained 24% of the variance in the mean z-score of all 6 cognitive domains. Comorbid lifetime alcohol use (n = 21) was not associated with cognitive dysfunction.Conclusions/SignificanceCognitive dysfunction in bipolar disorder is more severe in patients with depressive symptoms, especially regarding speed and attention. Therefore, interpretation of cognitive functioning in patients with depressive symptoms should be cautious. No association was found between cognitive functioning and lifetime comorbid alcohol use disorder.

Effect of alcohol and illicit substance use on verbal memory among individuals with bipolar disorder

“…Indeed, verbal memory deficits of large effect size have been consistently reported in BD (Bora, Yücel, Pantelis, & Berk, 2011), in particular with regard to immediate and delayed recall (Bora et al, 2009; Martínez-Arán et al, 2004; Van Der Werf-Eldering et al, 2010; van Gorp et al, 1998). Another study showed that immediate recall was significantly impaired in BD patients with more than 3 manic episodes when compared to HC (Cao, Passos, et al, 2016).…”

“…A history of substance use disorder has also been associated with reduced inhibition, poor visual memory and conceptual reasoning/set-shifting compared to patients with BD without past history of substance use (Houston et al, 2014; Marshall et al, 2012; Sanchez-Moreno et al, 2009; van Gorp, Altshuler, Theberge, Wilkins, & Dixon, 1998). Findings are however still controversial as at an appropriately powered study including BD patients with past and current lifetime use disorders found no link between cognitive impairment, more specifically in the memory domain, and AUD in BD patients (Van Der Werf-Eldering, Burger, Holthausen, Aleman, & Nolen, 2010). …”

Reduced white matter integrity and verbal fluency impairment in young adults with bipolar disorder: A diffusion tensor imaging study

“…Individuals with a MADRS score ≥20 (marker of moderate to severe depression) were excluded from the correlational analyses. This is based on previous evidence suggesting that measures of cognitive functioning collected during the severe phase of depression are not reliable indicators of individuals' mental abilities [46]. Demographic and cognitive results were considered to be statistically significant at a Bonferroni-adjusted p-value <.05.…”

P01-223-Recovery of cognitive functioning in patients with co-occurring bipolar disorder and alcohol dependence during early remission from an acute mood episode

“…Similarly, patients with AD suffer from significant cognitive impairment, even after extended periods of abstinence (29–35). Moreover, in both BD and AD, deficits in executive functioning are particularly predictive of poor prognosis and psychosocial disability (36–44). It is therefore possible that people who suffer from both conditions may be at greater risk for developing debilitating cognitive impairment and a more severe course of illness (25–27).…”