Bipolar Disorder: Causes, Stress and Diagnosis Explained
Why in the news
Bipolar disorder was in focus in April 2025 as a health topic, with attention on how genes, stress and body clocks combine to produce mood disorders.
Key facts
- Mood disorders involve pathological changes in mood, energy and activity that disturb everyday functioning.
- Major Depressive Disorder (MDD) shows up as lasting sadness, lost interest, fatigue, poor concentration, hopelessness and suicidal thoughts.
- Bipolar disorder swings between depression and mania (high mood, extra energy, little need for sleep, impulsive behaviour).
- Causes are multifactorial: genetic vulnerability plus environment. Heritability of bipolar disorder: 60-85%.
- Chronic stress causes HPA axis dysregulation: the cortisol-based stress response stays switched on after the stressor ends, leaving a chronic low-grade inflammatory state.
- Circadian rhythms (body temperature, melatonin release) are often disturbed during mood episodes; researchers have not settled whether this is a cause or an effect.
Stressors at a glance
| Type | Examples |
|---|---|
| Proximal stressors | Adverse childhood experiences such as abuse, neglect, domestic violence |
| Distal stressors | Adult-life problems such as money trouble, bereavement, trauma |
- Depressive relapses in bipolar disorder follow negative life events; manic relapses follow goal-attainment events.
Diagnostic challenges
- The illness frequently starts with depressive episodes, so it takes 6 to 10 years to reach the right diagnosis.
- Hypomanic episodes are easy to miss because people may enjoy the lifted mood and not seek help.
- Clinical red flags: early-onset depression, family history of bipolar disorder, unusual reaction to antidepressants, substance misuse or attention deficit disorder.
Exam angle
- Bipolar disorder = alternating depression and mania.
- Heritability range: 60-85%.
- Related terms: HPA axis, cortisol, melatonin, circadian rhythm, hypomania.