Bipolar disorder

Types and Symptoms: Understand the variations and clinical signs of bipolar disorder.
Pathophysiology: Explore the underlying physiological mechanisms.
Treatment Options: Learn about both pharmacological and non-pharmacological interventions.

Definition: Bipolar disorder, also known as manic depression, is characterized by cycles of manic (or hypomanic) and depressive episodes.
- Mania: A state of elevated mood with irritability and abnormal energy.
- Depression: Persistent low mood and diminished interest in activities.
- Hypomania: A milder form of mania with minimal impact on daily functioning.

Bipolar Disorder I: Involves full manic episodes, often with depressive episodes.
Bipolar Disorder II: Includes hypomanic episodes and significant depressive episodes.
Cyclothymic Disorder: Characterized by periods of hypomania and mild depression.

Mania:
- Symptoms lasting at least one week, impacting daily life.
- DSM-5 Criteria: Requires three or more of the following:
  - Inflated self-esteem or grandiosity.
  - Reduced need for sleep.
  - Increased talkativeness.
  - Racing thoughts.
  - Distractibility.
  - Elevated goal-oriented activity.
  - Risky behavior with potential negative outcomes.
Hypomania:
- Lasts at least four days without significantly impairing daily life.
- DSM-5 Criteria: Similar symptoms to mania but less severe.
Depression:
- Persistent depressed mood or loss of pleasure, often confused with unipolar depression if manic episodes are absent.

Assessment: Usually referred to a psychiatrist following GP evaluation. Consideration includes symptoms, medical history, and family history.
Challenges:
- Onset often between ages 15-19, but diagnosis typically occurs in the mid-20s.
- Early depressive symptoms may delay bipolar diagnosis, as they are often mistaken for unipolar depression.
Biological Markers: No specific detectable markers; diagnosis relies on clinical assessment.

Genetic Vulnerability:
- Bipolar disorder has a strong genetic component, with a high prevalence in first-degree relatives and monozygotic twins.
- Genome-wide association studies (GWAS) identified risk alleles in synaptic signaling pathways, particularly affecting the prefrontal cortex and hippocampus.
Environmental Factors:
- Triggers include relationship issues, abuse, loss of a loved one, and stress from illness or life changes.

Kindling Hypothesis: Suggests that stress triggers episodes, which over time become self-sustaining.
Neuroanatomical Factors:
- Imbalances in brain regions related to cognition and emotional regulation are implicated, aligning with the symptoms of mania.
Neurotransmitter Imbalance:
- Monoamine Hypothesis: Depression and mania are attributed to reduced and increased monoamine neurotransmission, respectively, though this is an oversimplification.

Pharmacological Approaches:
- Lithium:
  - Historical discovery of mood-stabilizing effects.
  - Complex mechanism involving enzyme inhibition, sodium channel effects, and neurotransmitter modulation.
  - Narrow therapeutic window (effective at 0.4-1 mmol/L; toxic above 1.5 mmol/L).
- Anticonvulsants:
  - Include carbamazepine, valproate, and lamotrigine.
  - Block voltage-gated sodium channels (VGSC), but vary in effectiveness for manic vs. depressive phases.
- Atypical Antipsychotics:
  - Drugs like olanzapine, quetiapine, and risperidone.
  - Mechanism involves D2 dopamine and 5-HT2A serotonin receptor antagonism.
Non-Pharmacological Approaches:
- Cognitive Behavioral Therapy (CBT):
  - Aims to change negative thought patterns.
  - Sessions generally conducted weekly or biweekly, for 6-20 sessions.
  - CBT may have an impact on neural circuits involved in mood regulation.
- Electroconvulsive Therapy (ECT):
  - Application of electrical stimulation to induce seizures, particularly effective for severe depression and treatment-resistant mania.
  - Quick relief of symptoms, especially useful in cases with life-threatening risks.