Bipolar Disorder — Causes, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Bipolar disorder (BD) is a chronic, episodic mood disorder characterised by recurrent episodes of mania (or hypomania) and depression, separated by periods of relative mood stability. It is classified into: Bipolar I disorder — manic episodes lasting at least 7 days (or any duration if severe enough to require hospitalisation), may include psychosis, with or without depressive episodes; Bipolar II disorder — hypomanic episodes (less severe mania, no psychosis, no hospitalisation required) alternating with major depressive episodes; and Cyclothymia — hypomanic and depressive symptoms that do not meet full criteria, persisting for 2 or more years. BD affects approximately 45 million people worldwide (lifetime prevalence 1-2%), with equal gender distribution. Mean age of onset is 17-21 years. Despite effective treatments, bipolar disorder carries a significant burden: 25-60% of patients attempt suicide (completion rate 7-15x general population); life expectancy is reduced by 9-20 years, predominantly from cardiovascular disease (associated metabolic syndrome and sedentary behaviour), suicide, and substance misuse. Many patients experience 10+ years of misdiagnosis (commonly as unipolar depression).

Bipolar disorder has a complex, multifactorial aetiology with strong genetic contribution. Heritability: approximately 85% (highest of all psychiatric disorders after autism); concordance in monozygotic twins 40-70%. First-degree relatives of a person with BD have a 5-10x increased lifetime risk. Genetic loci: GWAS have identified multiple risk variants — ANK3, CACNA1C (voltage-gated calcium channel — explaining action of calcium channel blockers in BD), NCAN, ODZ4; genetic overlap with schizophrenia and major depression. Neurobiological: dysregulation of circadian rhythms (explains why sleep disruption is a key trigger); prefrontal cortex thinning on MRI; mitochondrial dysfunction; abnormal dopaminergic and glutamatergic signalling; allostatic load from recurrent episodes (kindling hypothesis — each episode lowers threshold for next). Environmental and precipitating factors: sleep deprivation (a potent manic trigger — used to model mania experimentally); cannabis use (heavy cannabis use in adolescence doubles risk of BD; triggers acute mania/psychosis); stimulant use (cocaine, methamphetamine); major life stressors; antidepressant monotherapy (can trigger manic switch — antidepressants should never be used alone without mood stabiliser in BD); childbirth (postpartum period — especially high risk for mania and psychosis); photoperiod changes (spring peak in mania); and alcohol and substance misuse (comorbid in 40-60% of BD patients).

Manic episode (DSM-5 criteria — at least 7 days of persistently elevated, expansive, or irritable mood + at least 3 of: grandiosity (inflated self-esteem — patient may believe they are special, have special powers, or are on an important mission); decreased need for sleep (feeling refreshed after 2-3 hours); pressure of speech (rapid, difficult to interrupt); flight of ideas or racing thoughts; distractibility; increased goal-directed activity or psychomotor agitation; excessive involvement in high-risk activities: impulsive financial decisions (spending vast sums of money), sexual disinhibition, reckless driving, impulsive business schemes). Severe mania may include psychotic features (delusions of grandeur, auditory hallucinations — indistinguishable from schizophrenia if history unknown). Hypomanic episode: identical symptoms to mania but less severe, lasting at least 4 days, not requiring hospitalisation, and not causing marked functional impairment; many patients with BD II are not distressed during hypomania and do not present to services until depressive phase. Bipolar depression: identical to unipolar major depression (MDD) symptoms: low mood; anhedonia; anergia (profound fatigue and lack of energy); hypersomnia (sleeping 12-16 hours/day — more typical of BD depression vs. insomnia in MDD); increased appetite and weight gain; psychomotor retardation; poor concentration; and suicidal ideation. Mixed features (mixed affective state): concurrent manic and depressive symptoms — particularly dangerous — dysphoric, agitated, and suicidal simultaneously. Rapid cycling: 4 or more mood episodes per year — associated with worse prognosis.

Bipolar disorder is a clinical diagnosis based on DSM-5 or ICD-11 criteria — there are no diagnostic biomarkers or tests. A detailed longitudinal psychiatric history is essential — key questions to ask: have you ever felt so good, energised, or 'high' that others thought you were not yourself? Have you spent money impulsively or engaged in reckless behaviour? Did you ever need much less sleep than normal and not feel tired? NICE recommends using the Mood Disorder Questionnaire (MDQ) as a screening tool; a structured interview (SCID or MINI) is used in specialist practice. Rating scales: Young Mania Rating Scale (YMRS) for mania severity; Montgomery-Asberg Depression Rating Scale (MADRS) or PHQ-9 for depression severity. Differential diagnosis: unipolar major depression (the most common misdiagnosis — 40% of BD patients initially diagnosed with MDD; the distinction requires identifying previous hypomanic/manic episodes — often missed if not specifically asked); ADHD (distractibility, impulsivity, racing thoughts — overlapping); borderline personality disorder (BPD — mood instability, impulsivity — mood changes in BPD are shorter-lasting, reactively to interpersonal stress); schizophrenia (psychotic mania vs. psychosis — timeline and full mood history essential); substance use disorders (stimulants cause manic-like states; alcohol and benzodiazepine withdrawal cause mood instability). Blood tests: exclude medical causes of mood disturbance — TFTs (thyroid disease — hypothyroidism causes depression, hyperthyroidism causes anxiety/mania); FBC; U&E; LFTs; calcium; glucose; cortisol if Cushing's/Addison's suspected; toxicology screen. NICE recommends MRI brain for new-onset psychosis or if organic cause suspected. EEG if seizure disorder considered. Pre-treatment monitoring: ECG (antipsychotics prolong QTc); TFTs and renal function (lithium affects thyroid and kidneys); LFTs (valproate); fasting glucose and lipids (olanzapine, quetiapine — metabolic side effects).

Acute mania treatment: immediate environmental stabilisation and de-escalation; benzodiazepines (lorazepam 1-2 mg) for acute agitation; antipsychotic — haloperidol 5-10 mg IM (most evidence in rapid tranquillisation), or oral quetiapine 400-800 mg/day, olanzapine 10-20 mg/day, risperidone 4-6 mg/day, aripiprazole 15-30 mg/day; avoid antidepressants (may worsen and prolong mania). Bipolar depression: quetiapine 300 mg/day (NICE first-line — evidence from BOLDER trials); lamotrigine (effective but slow titration required — 6-week titration from 25 mg to 200 mg to avoid Stevens-Johnson syndrome); lithium plus psychoeducation; lurasidone; avoid antidepressant monotherapy without mood stabiliser cover (risk of manic switch). Long-term mood stabilisation (prophylaxis): lithium carbonate — first-line (NICE NG185): reduces episode frequency by 50-60%; reduces suicide risk by 60% (strongest anti-suicidal medication in psychiatry — Cipriani et al. Lancet 2013); requires serum level monitoring (target 0.6-0.8 mmol/L for maintenance — every 6 months once stable); thyroid and renal function monitoring every 6 months (lithium causes hypothyroidism in 20% and nephrogenic diabetes insipidus; rarely, irreversible renal failure — requires regular eGFR). Valproate: effective mood stabiliser — absolute contraindication in women of childbearing potential (highly teratogenic: spina bifida in 10%, neurodevelopmental disorders in 30-40% of children exposed in utero — NICE 2024 guidance). Lamotrigine: superior for bipolar depression prevention (less effective for mania); titration slow — risk of Stevens-Johnson syndrome with rapid titration. Quetiapine: effective for both phases; sedating — may suit patients with sleep disturbance. Structured psychoeducation (NICE recommended): 8-21 session group programme — teaches recognition of prodromal symptoms, lifestyle management, medication adherence; reduces episode frequency by 40% (Colom et al. BJPsych 2003). Cognitive Behavioural Therapy (CBT): effective adjunct for depression and relapse prevention. Sleep hygiene and circadian rhythm stabilisation: regular sleep-wake schedule; avoid night shifts and sleep deprivation — fundamental to bipolar management. Clozapine: for treatment-refractory BD with psychosis.

Bipolar disorder carries a high burden of serious complications without effective management. Suicide occurs in 7–15% of patients over their lifetime (25–60% attempt at some point) — the most serious complication, particularly during depressive or mixed episodes with concurrent agitation. Cognitive impairment (verbal memory, executive function, processing speed) accumulates with repeated mood episodes — the kindling hypothesis supports early and sustained mood stabilisation to minimise long-term neurobiological damage. Cardiovascular disease accounts for the majority of the 9–20 year reduced life expectancy, driven by metabolic syndrome from antipsychotics (particularly olanzapine and quetiapine), sedentary lifestyle, and high smoking prevalence (60%+ of BD patients smoke). Substance use disorders (alcohol, cannabis, stimulants) are comorbid in 40–60% and worsen mood cycling and overall prognosis. Psychosocial complications include relationship breakdown, unemployment (only 40–60% of BD patients maintain employment), financial difficulties from impulsive manic spending, and legal problems.

Preventing relapse in bipolar disorder requires vigilance and proactive management: maintain mood stabiliser medication adherence (lithium or valproate) — the most common cause of relapse is stopping medication; regular sleep schedule (maintain consistent wake time even at weekends — sleep disruption is the most potent manic trigger); avoid alcohol and recreational drugs (strongly associated with relapse — especially cannabis, cocaine, and stimulants); recognise personal prodromal warning signs (decreased sleep, elevated mood, increased energy, goal-directed behaviour for mania; withdrawal, low mood for depression — keep a mood diary); have a written crisis plan (advance directive, Wellness Recovery Action Plan — WRAP); maintain regular psychiatric follow-up; educate family members (carers can often recognise manic prodrome before the patient does); avoid antidepressant monotherapy; maintain regular physical activity (reduces depression and cardiovascular risk).

Call emergency services (999) or go to Emergency Department immediately for: active suicidal ideation with plan or intent in a depressive episode — bipolar depression carries very high suicide risk; psychotic mania (delusions, hallucinations, very disorganised behaviour) — requires urgent psychiatric assessment and possible involuntary detention under the Mental Health Act; mixed affective state (simultaneously agitated, dysphoric, and suicidal) — particularly high-risk period; person refusing all food, fluids, or medication. Call 111 or contact Community Mental Health Team (CMHT) urgently for: rapid deterioration in mood over 24-48 hours with reduced sleep need (early mania) — prompt intervention can prevent hospitalisation; significant increase in risky behaviour — financial, sexual, driving; family reporting concerning behavioural change. Alert psychiatrist or GP promptly if: stopping mood stabiliser medication — always discuss before stopping lithium (abrupt cessation causes rebound mania); pregnancy or planning pregnancy — valproate must be changed, lithium requires careful planning; significant life events (bereavement, job loss, relationship breakdown) — increase monitoring frequency around these triggers.