Bipolar Disorder is a mood disorder characterized by alternating episodes of mania or hypomania (elevated energy and mood) and episodes of depression. According to the DSM-5-TR and ICD-11, it is mainly distinguished between two subtypes:

• Bipolar I: At least one manic episode (duration ≥ 7 days or hospitalization) that may be preceded or followed by major depressive episodes.
• Bipolar II: At least one hypomanic episode (≥ 4 days, without loss of contact with reality) and one major depressive episode; mania has never occurred.

Mood cycles vary between people: some experience acute phases spaced by long remissions; others have rapid cycles (≥ 4 episodes/year).

Causes and Risk Factors of Bipolar Disorder

• Genetics – Estimated heritability of 60–80 %; first-degree relatives have a seven times higher risk.
• Neurobiology – Dysfunctions in the limbic circuits (amygdala, prefrontal cortex) and in the dopaminergic, serotonergic, and glutamatergic systems.
• Environmental stress Significant life events (loss, jet lag, night work) can trigger episodes in predisposed individuals.
• Circadian rhythms – Disruptions in the sleep-wake cycle worsen mood instability.
• Substance use Alcohol, cannabis, and psychostimulants can trigger or intensify episodes.