Cerebral asymmetry in bipolar disorders: A scoping review

Moebus, Lukas; Quirin, Markus; Ehrlenspiel, Felix

doi:10.1016/j.biopsycho.2023.108551

Cited by 3 publications

(4 citation statements)

References 68 publications

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“…Fourth, unfortunately, most studies did not differentiate between the type of BD (type I or II), nor did they assess acute manic or depressive episodes when testing the subjects. Grouping the results from individuals with a current manic episode or BD type I diagnosis with individuals with a current depressive episode or a type II BD diagnosis potentially dilutes effects that would be more pronounced in manic episodes as seen in the neuroimaging data (Moebus et al 2023 ). Another possibility would be that individuals may show stronger left lateralization during manic episodes compared to depressive episodes and not a general atypical side preference.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, a group of researchers performed a review on cerebral asymmetries in BD subjects given the proposed role of cerebral asymmetry in the pathophysiology of BD (Moebus et al 2023 ). To this end, they summarized resting-state and task-based functional cerebral asymmetries in manic and depressive episodes in BD subjects.…”

Section: Introductionmentioning

confidence: 99%

“…Interestingly, the findings highlight a left-hemispheric dominance in the frontal lobe during manic episodes but a right-hemispheric dominance in regions of the frontal and temporal lobe in BD depression. The researchers further underline that these differential asymmetries in BD are important to consider for brain stimulation protocols and thus warrant further investigation (Moebus et al 2023 ). While these findings are important, behavioral asymmetries were not included in this analysis, making it unclear whether behavioral asymmetries are altered in BD or not.…”

Section: Introductionmentioning

confidence: 99%

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Behavioral lateralization in bipolar disorders: a systematic review

Mundorf,

Borawski,

Ocklenburg

2023

Int J Bipolar Disord

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Background Bipolar disorder (BD) is often seen as a bridge between schizophrenia and depression in terms of symptomatology and etiology. Interestingly, hemispheric asymmetries as well as behavioral lateralization are shifted towards a tendency of left-side or mixed-side bias in schizophrenia whereas no shift is observed in subjects with depression. Given the role of BD with both, (hypo)manic and depressive episodes, investigating hemispheric asymmetries in subjects with BD is an interesting objective. Method A systematic review of studies including measures of behavioral lateralization in the form of handedness, footedness, eyedness, and language lateralization was performed resulting in 25 suitable studies. Results A broad variety of methods was used to assess behavioral lateralization, especially for eyedness, footedness, and language lateralization hindering the integration of results. Additionally, for hand preference, studies frequently used different cut-off scores and classification systems. Overall, studies do not support alteration in side preference in BD subjects. Studies focusing on differences in handedness demonstrate that subjects show equal rates of right- and non-right-handedness as the general population. Few studies focusing on manic episodes point towards increased left-side bias in ear and eye dominance, but the small sample sizes and conflicting results warrant further investigation. Conclusion The results reinforce that some disorders, such as BD, should not be treated as a homogenous group but sub-groups should be analyzed within the patient’s population. Particularly, clinical implications resulting from neuroimaging studies highlight the need to study hemispheric asymmetries given that they may be important to consider for brain stimulation protocols.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Behavioral lateralization in bipolar disorders: a systematic review

Mundorf,

Borawski,

Ocklenburg

2023

Int J Bipolar Disord

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“…These inconclusive findings might be due to the diverse nature of brain dysfunction in the manic versus depressed phases in BD patients. In a similar line of observation, a recent review of 10 resting-state EEG along with task-related fMRI studies in BD concluded the cerebral dominance of “the left dorsolateral prefrontal cortex and dorsal anterior cingulate cortex” in the manic phase, but cerebral dominance of the “right dorsolateral prefrontal cortex, orbitofrontal cortex and temporal pole” in the depressive phase of BD [ 59 ]. An earlier longitudinal qEEG study of BD also reported that the asymmetry of the frontotemporal slow-wave activity in depression exhibits an opposite direction compared to mania [ 60 ].…”

Section: Evidence Linking the Loss Of Brain Asymmetry To Mental Illne...mentioning

confidence: 93%

Epigenome Defines Aberrant Brain Laterality in Major Mental Illnesses

Abdolmaleky,

Nohesara,

Thiagalingam

2024

Brain Sciences

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Brain-hemisphere asymmetry/laterality is a well-conserved biological feature of normal brain development. Several lines of evidence, confirmed by the meta-analysis of different studies, support the disruption of brain laterality in mental illnesses such as schizophrenia (SCZ), bipolar disorder (BD), attention-deficit/hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), and autism. Furthermore, as abnormal brain lateralization in the planum temporale (a critical structure in auditory language processing) has been reported in patients with SCZ, it has been considered a major cause for the onset of auditory verbal hallucinations. Interestingly, the peripheral counterparts of abnormal brain laterality in mental illness, particularly in SCZ, have also been shown in several structures of the human body. For instance, the fingerprints of patients with SCZ exhibit aberrant asymmetry, and while their hair whorl rotation is random, 95% of the general population exhibit a clockwise rotation. In this work, we present a comprehensive literature review of brain laterality disturbances in mental illnesses such as SCZ, BD, ADHD, and OCD, followed by a systematic review of the epigenetic factors that may be involved in the disruption of brain lateralization in mental health disorders. We will conclude with a discussion on whether existing non-pharmacological therapies such as rTMS and ECT may be used to influence the altered functional asymmetry of the right and left hemispheres of the brain, along with their epigenetic and corresponding gene-expression patterns.

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