The Converging Effects of Neurocognitive Deficits and Bipolar Emotion

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Cognitive deficits may persist during periods of remission in patients with bipolar disorder.
Cognitive deficits may persist during periods of remission in patients with bipolar disorder.

Potential links between neurocognitive deficits and emotion in bipolar disorder (BD) have begun to emerge, although there is no current evidence to support a shared pathology. A 2017 review by Lima, et al1 pointed to several studies that reported a correlation between lower performance on cognitive tests in patients diagnosed with BD. While cognitive deficits have been clearly observed during both manic and depressive phases of BD, research suggests that cognitive signs are significantly less prominent during periods of remission.2,3  

According to Tamsyn E. Van Rheenen, PhD, NHMRC Peter Doherty Biomedical Research Fellow at the Melbourne Neuropsychiatry Centre, University of Melbourne in Australia, “It is well recognized that many people with bipolar disorder experience cognitive deficits at the same time as they experience depressive symptoms, although it is also clear that these deficits persist even when depressive symptoms have remitted.”

Patient-Reported Impact on Quality of Life

A study of individuals from Massachusetts General Hospital in Boston with BD1 by Peters, et al3 showed that patients were able to recognize cognitive deficits and their impact on quality of life (QoL) in ways that were not measurable on laboratory-based cognitive function tests.

Multiple cognitive domains appeared to be negatively affected during acute phases of BD, including attention, psychomotor speed, visuospatial abilities, executive function, decision-making, memory and learning, as well as emotion processing.3-6  In addition, symptoms of neurocognitive impairment persist during periods of emotional stability.7 The Peters study reported that the presence of mood symptoms specifically predicted dysfunction in attention and executive function skills, while mood severity predicted memory interference, all of which contributed to impaired function in daily activities.3

Do Cognitive Signs Predict BD or Vice Versa?

The question of whether measures of affective temperament may be considered markers for neurocognitive aspects of BD is a point of investigation in many studies. Dr. Van Rheenen told Psychiatry Advisor, “While mood symptoms related to depression or mania may indicate an increase in the severity of cognitive symptoms in people with bipolar disorder, they are unlikely to be a marker of cognitive deficits themselves. There is an increasing body of research indicating that a large proportion of people with bipolar disorder experience cognitive deficits even during euthymic mood periods. These persistent cognitive deficits are believed to contribute to the ongoing difficulties in activities of daily functioning that some people with bipolar disorder experience, irrespective of the mood state they are in.”

A 2014 study by Van Rheenen, et al8 examined patterns of dysfunction of social cognition and neurocognitive and evaluated 3 hypotheses that may help explain their role in BD:

  1. Neurocognition has a direct influence on bipolar emotional regulation
  2. Neurocognition influences emotional perception and theory of mind (ToM) features of social cognition
  3. Social cognition exerts a direct influence on emotional regulation

Using a battery of tests in 51 patients with BD and 52 healthy controls, the Van Rheenen study8 directly evaluated these features and reported that neurocognitive deficits was predictive of emotional perception and theory of perception in BD, validating hypothesis 2.

At the same time, they found that variations in social and neurocognitive function in patients with BD compared with controls were regulated separately from the emotional component, challenging the validity of hypothesis 3. Likewise, there was no significant evidence of a shared pathway between cognition and emotional regulation that validated hypothesis 1.

Treatment

Pharmacologic management of BD becomes more complicated in light of potentially overlapping neurocognitive symptoms and mood dysregulation. “Clinicians are becoming more knowledgeable that these deficits could hinder the development of an effective therapeutic relationship or the success of psychological treatment itself,” Dr. Van Rheenen said, adding that for these reasons, “There has been an increasing push to find pharmacological and psychological treatments to improve cognitive deficits for people with bipolar disorder in recent years. Previously it was assumed that by treating mood symptoms the associated cognitive deficits would be ameliorated.”

Dr. Van Rheenen has explored this convergence of cognition and emotional signs in BD across several studies.2,8 “A new awareness that cognitive deficits persist even when mood symptoms are adequately controlled has increased the research focus on finding adequate treatments for the cognitive deficits themselves,” she observed. “The research community is currently trying to understand whether cognitive treatments that have been used in other disorders can be adapted to treat bipolar disorder. At the moment there is ongoing research to refine the ways in which cognitive treatment is delivered and its effectiveness measured in clinical trials.”

The challenges to treatment are multifold. Peters and colleagues pointed out that heavy loads of psychotropic medications impair specific domains of cognitive function without affecting others — an area that needs to be further explored.3  Van Rheenen and colleagues concluded that their findings “highlight the importance of incorporating cognitive and emotion regulation assessments into clinical practice when working to reduce psychosocial dysfunction with patients diagnosed with BD.”2

References

  1. Lima IMM, Peckham AD, Johnson SL. Cognitive deficits in bipolar disorders: Implications for emotion. Clin Psychol Rev 2018;59:126-136.
  2. Van Rheenen TE, Rossell SL.Objective and subjective psychosocial functioning in bipolar disorder: an investigation of the relative importance of neurocognition, social cognition and emotion regulation.J Affect Disord 2014;162:134-141.
  3. Peters AT, Peckham AD, Stange JP, et al. Correlates of real world executive dysfunction in bipolar I disorder. J Psychiatr Res, 2014;53:87-93.
  4. Burdick KE, Braga RJ, Goldberg JF, Malhotra AK. Cognitive dysfunction in bipolar disorder: future place of pharmacotherapy. CNS Drugs 2007;21:971e81.
  5. Goldberg JF, Chengappa KN. Identifying and treating cognitive impairment in bipolar disorder. Bipolar Disord 2009;11(Suppl 2):123e37.
  6. Zarate Jr CA, Tohen M, Land M, Cavanagh S. Functional impairment and cognition inbipolar disorder. Psychiatr Q 2000;71:309e29.
  7. Thompson JM, Gallagher P, Hughes JH, Watson S, Gray JM, Ferrier IN, et al. Neurocognitive impairment in euthymic patients with bipolar affective disorder. BrJ Psychiatry. 2005;186:32e40.
  8. Van Rheenen TE, Meyer D, Rossell SL. Pathways between neurocognition, social cognition and emotion regulation in bipolar disorder.Acta Psychiatr Scand 2014;130:397-405.
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