Bipolar Disorder: Clinical Features, Causes, Diagnosis, and Treatment

Article written in collaboration with @taniacatasso_psicologa

Introduction

Bipolar disorder is a chronic psychiatric condition characterized by recurrent episodes of mania or hypomania and depression, with intervening periods in which symptoms are absent or subthreshold (Oliva et al., 2024). According to the World Health Organization (WHO, 2026), about 36 million people worldwide were living with the disorder in 2023, including 3.3 million adolescents aged 10 to 19. Despite its prevalence, identification remains difficult and often delayed. This article reviews its clinical, diagnostic, etiological, and therapeutic aspects.

A Phasic Disorder, Not Simply Mood Swings

The defining feature of bipolar disorder is its phasic nature: the person goes through distinct phases with significant alterations in mood, energy, and activity. According to the DSM-5-TR (American Psychiatric Association [APA], 2022), a manic episode lasts at least seven days and involves an elevated, expansive, or irritable mood with an abnormal increase in activity or energy. A hypomanic episode requires at least four consecutive days and is less severe, as it does not cause marked impairment in functioning or require hospitalization. A major depressive episode lasts at least two weeks and involves depressed mood or loss of interest and pleasure, along with other associated symptoms, including sleep and appetite disturbances, psychomotor slowing or agitation, guilt, and difficulty concentrating.

The WHO (2026) describes manic symptoms as euphoria or irritability, increased activity and energy, talkativeness, racing thoughts, inflated self-esteem, reduced need for sleep, distractibility, and impulsive, risky behavior. Phases may alternate rapidly or be separated by periods of relative well-being (euthymia).

Autobiographical accounts help convey what the experience is like. Jamison (1995), a clinical psychologist who herself lives with the illness, describes the elevated phase as a flow of fast ideas and sensations in which shyness vanishes and confidence in relating to others grows. She also describes a blend of pain, elation, loneliness, and terror that sets the experience apart from a simple period of good mood or sadness. This is useful for distinguishing bipolar disorder from normal emotional fluctuations or the affective lability of other clinical conditions.

The Bipolar Spectrum

The DSM-5-TR devotes a specific chapter to bipolar disorders, which includes bipolar I disorder, bipolar II disorder, and cyclothymic disorder, along with the "other specified" and "unspecified" forms (APA, 2022; Jain & Mitra, 2023). The ICD-11 also uses the term "bipolar and related disorders," in line with the DSM-5 (Jain & Mitra, 2023).

Bipolar I disorder requires at least one manic episode during the lifetime. Bipolar II disorder requires at least one major depressive episode and at least one hypomanic episode, with no manic episodes. Cyclothymia involves, for at least two years in adults, frequent mood alterations that do not reach the threshold for full episodes (APA, 2022).

Bipolar II disorder is sometimes perceived as a "mild" form, but the data do not support this. A review of 101 studies on suicide attempts found similar risks in bipolar I (29.9%) and bipolar II (31.4%) disorder (Tondo et al., 2016). Genetics also suggests continuity: analyses of large samples indicate a high but imperfect genetic correlation between the two subtypes (Mullins et al., 2021).

The Diagnostic Challenge

Diagnosis remains one of the main clinical challenges. Bipolar disorder is often misdiagnosed in its early stages (Jain & Mitra, 2023), particularly as unipolar depression, because people mainly seek help during depressive phases, while hypomanic episodes may be experienced as periods of well-being or productivity and go unreported.

A meta-analysis of 27 studies estimated the average interval between illness onset and clinical management at 5.8 years, with high heterogeneity across samples, partly related to how onset and management are defined (Dagani et al., 2017). The delay has concrete consequences: a wrong diagnosis can lead to inappropriate treatment and a worse course of illness. More recent reviews add that clinical management is complicated by the variability of clinical presentations, the absence of specific biomarkers, and differences in guidelines across world regions (Oliva et al., 2024).

Causes: A Multifactorial Etiology

Bipolar disorder has a substantial genetic component, but it does not depend on a single gene. The largest genome-wide association study conducted to date, involving 41,917 cases and 371,549 controls of European ancestry, identified 64 associated genomic loci. Risk variants were enriched in genes involved in synaptic signaling and in neurons of the prefrontal cortex and hippocampus (Mullins et al., 2021). The picture is therefore polygenic: many variants, each with a small effect.

Genetics alone cannot explain the disorder. Genetic, neurobiological, and environmental factors interact, and the disorder is often accompanied by psychiatric and medical comorbidities that complicate diagnosis and treatment (Oliva et al., 2024). A practical implication follows: an integrated understanding of the disorder, both biological and psychosocial, is the foundation of effective intervention.

Suicide Risk and Physical Health

Bipolar disorder carries an increased risk of suicide (WHO, 2026). International guidelines note that lithium and, to a lesser extent, anticonvulsants may help prevent suicide attempts and deaths, while specifying that further data are needed on their relative efficacy (Yatham et al., 2018). Regularly assessing suicide risk, particularly during depressive phases and transitions between phases, is therefore an essential component of care.

Treatment

The 2018 CANMAT/ISBD guidelines synthesize the evidence on the efficacy, safety, and tolerability of treatments and rank them by phase of illness: mania, bipolar depression, hypomania, and mixed states, as well as maintenance (Yatham et al., 2018). Specific pharmacological choices are the responsibility of the treating psychiatrist and should be consulted directly in the updated guidelines.

Treatment is not exclusively pharmacological. The WHO lists psychoeducation, strengthening of social functioning, and medication among effective interventions (WHO, 2026). Group psychoeducation has a substantial evidence base. In a randomized trial of patients with bipolar I and II disorder in remission and receiving pharmacological treatment, 21 sessions of group psychoeducation reduced the number of patients who relapsed and the number of recurrences per patient, and lengthened the time to new episodes, compared with unstructured group meetings (Colom et al., 2003).

For completeness, the results are not unequivocal. A large pragmatic multicenter trial found that structured psychoeducation was no more effective than peer support of comparable intensity in terms of time to relapse, but was more acceptable and produced better outcomes in participants with fewer previous episodes (Morriss et al., 2016). This suggests that psychosocial interventions may be particularly useful in the early stages of the illness and that the choice should be personalized.

Lived Experience and Stigma

First-person narratives such as Jamison's (1995) remind us that behind diagnostic criteria lies a complex subjective experience, made up of suffering but also of awareness and a search for meaning. Reducing stigma, improving knowledge of symptoms, and promoting early access to care are both clinical and cultural goals. Recent reviews also point to important gaps, particularly in access to equitable care worldwide, and identify precision psychiatry and digital tools as promising future directions (Oliva et al., 2024).

Conclusions

Bipolar disorder is a chronic, recurrent, and treatable condition. Early recognition, differentiation from unipolar depression and from normal emotional fluctuations, assessment of suicide risk, and integrated treatment combining pharmacotherapy and psychosocial interventions are the cornerstones of care. Important questions remain open, such as reducing diagnostic delays and personalizing treatment.

References

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