Bipolar disorder (BD) is a neuropsychiatric disorder characterized by recurring (hypo) manic and depressive episodes with an estimated prevalence of 1–2% worldwide (Blanco et al., 2017). Common symptoms of manic episodes include an expansive or irritated mood, highly elevated activity, decreased need for sleep, overconfidence, grandiosity, talkativeness, and impulse disinhibition (Carvalho et al., 2020). Contrary, depressive episodes encompass, among others, persistent sadness, loss of interest or pleasure, fatigue, sleep disturbances, and feelings of worthlessness or guilt (Dilling and Freyberger, 2019). In both mood states, cognitive deficits including attention, memory, and executive function impairments occur frequently and often persist during euthymia, especially in longer illness durations (Chen et al., 2023; Tsapekos et al., 2021). Due to these debilitating symptoms, BD was ranked as one of the 20 leading causes of disability worldwide (Anyayo et al., 2021; Arvilommi et al., 2022), and the worldwide prevalence of moderate to severe disability for BD is estimated at approximately 22 million individuals (Chen et al., 2019). One of the driving aspects of disability in BD is the low level of functioning, which differs slightly across mood states (Rosa et al., 2009; Van Der Voort et al., 2015) and serves as a key domain of illness outcome (Gitlin and Miklowitz, 2017), low quality of life, productivity loss (Kato et al., 2021), and suicidality (Rosa et al., 2008).

Functioning represents a multidimensional concept, including the ability to perform and engage in various life situations (World Health Organization, 2015), as well as managing aspects of the environment that help or hinder these life experiences (Chen et al., 2019). Over the past decades, the term global functioning, which subsumes the measurement of several types of functioning, has emerged (Aas, 2010). Global functioning encompasses, among others, psychosocial functioning (i.e., the ability to sustain social relationships and engage in activities of daily life; Michalak et al., 2010), occupational and educational functioning (i.e., the ability to perform work-related skills; Duarte et al., 2016), cognitive functioning (using cognitive function in real-world settings; Miskowiak et al., 2012), and physical functioning (e.g., mobility, dexterity, carrying out instrumental activities of daily living; World Health Organization, 2015). Individuals with BD often show low levels of functioning in these areas (Gitlin and Miklowitz, 2017; Sylvia et al., 2017), which affects them and their social structures (Baune and Malhi, 2015). For instance, they report severe work impairment (Boland et al., 2015; Marwaha et al., 2013), high unemployment rates (Holm et al., 2020), decreased social resources (Greenberg et al., 2014; Studart et al., 2015), and more barriers to higher education (Kruse and Oswal, 2018; Mojtabai et al., 2015). These functional impairments persist into symptomatic remission (Gitlin and Miklowitz, 2017; Léda-Rêgo et al., 2020), show great heterogeneity among individuals with BD (Solé et al., 2018), and lead to several difficulties in daily life (Chen et al., 2019). Since for many individuals with BD and their caregivers, functioning is at times more important than symptomatic outcome, much research has been dedicated to identifying its determinants. For instance, male sex, lower levels of education, lower socio-economic status, longer illness duration, a higher number of episodes, the presence of comorbid psychiatric disorders, and a greater current number of psychopharmacological medications have been found to predict functional impairment in BD (Burdick et al., 2022; Hower et al., 2019; Sanchez-Moreno et al., 2018; Wingo et al., 2010). Moreover, persistent subsyndromal symptoms, especially residual depressive symptoms, a history of psychosis (Bonnín et al., 2019; Bowie et al., 2010), and the number of admissions have been reported to have a negative impact on functioning (Sanchez-Moreno et al., 2017). Next to clinical and demographic variables, cognition has been found to be a predictor of functioning in BD in some studies (Burdick and Millett, 2021; Depp et al., 2012; Van Rheenen et al., 2019).

Cognition is usually conceptualized in terms of hierarchically ordered domains of cognitive function (i.e., the bottom domains refer to basic sensory and perceptual processes, and the top domains refer to executive function and cognitive control). The cognitive function domains encompass attention and concentration, memory, executive function, processing speed, and language/verbal skills (Harvey, 2019). In BD, a study revealed that 30–50% show impairments in cognition, predominantly in the areas of verbal memory, processing speed, executive function, attention, working memory, and social cognition (average illness duration: 15.61 years, average episode number: 11.28 episodes; Lima et al., 2019). Former studies reported that cognitive dysfunction is also related to demographic [e.g., age (Frías et al., 2017; Rabelo-da-Ponte et al., 2022; Mann-Wrobel et al., 2011), education (Rabelo-da-Ponte et al., 2022; Mann-Wrobel et al., 2011), sex (Martín-Parra et al., 2024)] and clinical outcomes [e.g., symptomatology; (Frías et al., 2017), number of hospitalizations (Rabelo-da-Ponte et al., 2022), illness duration (Mann-Wrobel et al., 2011), illness onset (Bortolato et al., 2015)]. Moreover, cognitively impaired individuals with BD were shown to display more functional disabilities than those without cognitive impairment (Jensen et al., 2016). The strength of the association between cognitive abilities and psychosocial functioning in BD was previously reported to be similar to that seen in schizophrenia (Depp et al., 2012). This may exacerbate the challenges that individuals with BD face in daily life, leading to greater difficulties in managing personal, social, and occupational responsibilities.

A paucity of studies have reported on the association between cognition and functioning in BD (e.g., Anaya et al., 2015; Martínez-Arán et al., 2004; Miskowiak et al., 2023; Chen et al., 2021), with most of them finding that specific cognitive abilities are predictors of functional outcomes (Bonnín et al., 2010; Lee et al., 2015; Lomastro et al., 2020; López-Villarreal et al., 2020; Ponsoni et al., 2020). While some of the studies identified executive function, verbal learning/memory (Martínez-Arán et al., 2004; Bonnín et al., 2010), verbal fluency, and working memory (Chen et al., 2021) as the predictors with the most impact on psychosocial functioning, others found that sustained attention and psychomotor speed are also important within this context (Lee et al., 2015; López-Villarreal et al., 2020). To strengthen the knowledge on these complex associations, the current study aimed to investigate the cross-sectional association between cognitive abilities and functioning. Based on previous findings, it was hypothesized that (a) there would be a significantly positive relationship between the cognitive abilities (a) attention/psychomotor speed, (b) verbal learning/memory, and (c) executive function and psychosocial functioning. Moreover, it was hypothesized that (d) attention/psychomotor speed, (e) verbal learning/memory, and (f) executive function can predict psychosocial functioning, independently of age, sex, and educational level.

The current study investigated the association and prediction of psychosocial functioning by the cognitive domains attention/psychomotor speed, verbal learning/memory, and executive function. Our cross-sectional analysis showed a significantly positive association between attention/psychomotor speed, verbal learning/memory and functioning, indicating that greater abilities within these domains are related to better functioning. However, when considering the control variables age, sex, and education within hierarchical regression analyses, no cognitive domain was able to explain significant unique variance in functioning. This reflects that cognitive abilities are not predictors of psychosocial functioning beyond age, sex, and education in individuals with BD. Instead, other factors are more likely to explain psychosocial functioning of patients with psychiatric disorders, such as emotion regulation, social support, and illness-related variables. In addition, the self-assessment of cognitive deficits has also recently been linked to functioning and has been identified as an independent predictor of functional outcomes in schizophrenia (Silberstein and Harvey, 2019).

However, our hypotheses, which state that there is a significantly positive relationship between the cognitive domains (a) attention/psychomotor speed, (b) verbal learning/memory, (c) executive function and psychosocial functioning, can partly be confirmed by our results. Our finding of a positive association between attention/psychomotor speed, verbal learning/memory, and functioning is in line with previous studies, which found that impaired abilities in the domains verbal learning/memory (Bonnín et al., 2010) and attention (Jaeger et al., 2007), specifically sustained attention, were related to reduced functional disability (Lee et al., 2015). Moreover, another study found that lower performance in verbal memory, working memory, verbal fluency, and processing speed was associated with decreased functioning in BD (Sanchez-Moreno et al., 2018). Other studies reported that verbal memory represents a core deficit in BD and is one of the best predictors of functioning (Martínez-Arán et al., 2004), specifically occupational functioning (Burdick et al., 2010). The finding that none of the cognitive domains predicted functioning beyond the control variables age, sex, and education contradicts our hypotheses (d-f) and the existing literature. Most previous studies point toward a neurocognitive impairment as a main predictor of psychosocial functioning (for a review, see Keramatian et al., 2021). It should be noted that psychosocial functioning is a complex construct influenced by various non-cognitive factors, such as emotional regulation (Van Rheenen and Rossell, 2014), social support (Wang et al., 2018), illness severity (Goldstein et al., 2009; Schaub et al., 2011), and psychosocial treatment (Reinares et al., 2014). It is possible that these factors play a more dominant role in determining functional outcomes (Depp et al., 2012), thereby diminishing the predictive value of cognitive abilities in our regression analyses.

Another explanation for the non-significant regression analyses results might be the use of a single global functioning scale (the GAF as an external rating) and the creation of overarching cognitive composite scores. Studies that found an effect of cognitive abilities on functional outcomes often used measurements, which differentiated in more detailed aspects of both functioning (e.g., functioning in employment, relationship, and independent living, such as the Functioning Assessment Short Test (Rosa et al., 2007) or Work and Social Adjustment Scale (Mundt et al., 2002)) and/or cognitive domains (e.g., psychomotor speed, sustained attention; Lee et al., 2015; Flaaten et al., 2024). Possibly, the lack of differentiation into the sub-facets of both functioning and cognition might have led to a non-significant association. In addition, the participants in our sample reached test scores within 1.5 standard deviations below and above the normative performance of each test (T-scores of all cognitive tests ranged between M = 43.31–60.25 and SD = 7.83–13.89). This indicates that, on average, our sample showed unimpaired cognitive performance, which might have contributed to the non-significant association between cognitive abilities and psychosocial functioning. We also included individuals from our outpatient clinic, who might have a greater level of functioning, as reflected by a mean GAF score of 68.90 (SD = 13.01). Investigating our hypotheses in a sample with a greater range of functioning might have led to different results. Moreover, we only used data from individuals, who met the criteria for current euthymia. Other studies, which found that cognition predicts functioning in BD, analyzed data of individuals in a current affective episode (e.g., Platania et al., 2023; Torres et al., 2011; Karantonis et al., 2020), which might have led to different study outcomes. One study, which investigated the effect of clinical and cognitive variables on functioning at two measurement times in a five-year interval, reported that verbal memory at baseline and change in sustained attention during follow-up explained only 6–10%, but clinical variables (e.g., number of hospitalizations) explained up to 30% of the variance in psychosocial functioning (López-Villarreal et al., 2020). This strengthens again the assumption that other variables might exert a greater influence on functioning than cognition, such as clinical course, medication, life events, or coping styles (Fletcher et al., 2014; Sato et al., 2018; Miskowiak et al., 2023). These findings are in line with the results of the current study, which depict that demographic variables such as age and education play a more important role in explaining variance in functioning than cognitive abilities.

This study investigated the relationship between cognitive domains and psychosocial functioning in individuals with BD, revealing a positive association between attention/psychomotor speed, verbal learning/memory, and functioning. However, when controlling for age, sex, and education, these cognitive domains did not significantly predict functioning, which highlights the predominant role of demographic factors in this model. These factors are known to have a substantial impact on both cognitive performance and functional outcomes, potentially reducing the unique predictive power of cognitive domains when considered together, which needs to be considered in further studies in this area. To conclude, while our findings support prior research, which demonstrates an association between cognitive abilities and functioning, they also challenge existing literature that refers to cognition as a main predictor of functioning. Future research should incorporate more detailed functional and cognitive assessments and consider clinical variables to clarify the complex mechanisms between cognition and psychosocial functioning. Understanding these relationships is essential for developing targeted interventions that facilitate daily life in individuals with BD.