Pathogenesis (disease development)
The cause of bipolar disorder is thought to be multifactorial. Genetics, in particular, play a role, as do personality characteristics and environmental factors.
Herpes viruses may also play a role in the pathogenesis of bipolar disorder: patients with bipolar and major depressive disorder were found to have a high rate of infection with the human herpes virus HHV-6 in Purkinje neurons.
Risk factors for frequent recurrent episodes.
- Female sex
- Young age of onset
- Serious life events
- Mixed episodes
- Psychotic symptoms
- Rapid cycling (rapid alternation between depressive and manic episodes; ≥ 4 affective episodes in 12 months)
- Insufficient response to therapy (phase prophylactic therapy).
Risk factors for a chronic course
- Frequent episodes
- Premorbid personality
- Poor compliance
- Insufficient response to therapy (acute/phase prophylactic therapy).
- Other mental/somatic illnesses
- Additional substance abuse
Etiology (causes)
Biographical causes
- Genetic burden from parents, grandparents
- Genetic risk depending on gene polymorphisms:
- Genes/SNPs (single nucleotide polymorphism):
- Genes: ANK3
- SNP: rs4948418 in the gene ANK3
- Allele constellation: TT (2.10-fold).
- Allele constellation: CT (1.45-fold)
- Allele constellation: CC (0.94-fold)
- Genes/SNPs (single nucleotide polymorphism):
- A genome-wide association study (GWAS) detected a total of 30 regions associated with bipolar disorder; it also genetically distinguished two subtypes of the disorder:
- Type I, with more pronounced manic and depressive phases, appears to be more related to schizophrenia at the genetic level
- Type II suggests a “milder” course with a relationship to depression
- Genetic risk depending on gene polymorphisms:
- Positive family history
- Temperament abnormalities
Behavioral causes
- Nutrition
- Consumption of foods cured with nitrate salts: Patients hospitalized for a manic episode were 3.5 times more likely to have ever eaten meat cured with nitrate than persons who did not have a severe psychiatric disorder (odds ratio = 3.49, 95% confidence interval 2.24-5.45, p < 8.97 × 10-8). Note: Rat experiments with nitrate-containing diets confirm the risk of mania. Note: Nitrates and nitrites are also present in vegetables and salads. Seasonal vegetables contain fewer nitrates.
- Substance dependence, unspecified (alcohol; cannabis (hashish and marijuana)).
- Circadian rhythm disorder (disturbance of the day-night rhythm), i.e., increased activity during nocturnal rest periods and inactivity during the day
Environmental stress – intoxications (poisonings).
- Regions with particularly poor air quality