Table 2 Strength of evidence for biological factors supporting merging in some way schizophrenia, schizoaffective and bipolar I disorder
| Biological factor | Strength of evidence |
|---|---|
| Genetics—family studies | Strongest |
| Genetics—twin studies | Moderate |
| Genetics—candidate gene/GWAS | Moderate |
| Brain—morphology | Moderate |
| Pharmacotherapeutics—lithium, divalproex, lamotrigine, antipsychotics | Weak |