Developmental theories of schizophrenia say that something goes wrong when the brain is developing. Brain development, from the earliest stage of fetal development through the early years of life, is an extremely complicated process. Millions of neurons are formed, migrate to different regions of the forming brain, and specialize to perform different functions.
The “something” that goes wrong might be a viral infection, a hormonal imbalance, an error in genetic encoding, a nutritional stress, or something else. The common element in all developmental theories is that the causal event occurs during the brain’s development.
Symptoms of schizophrenia typically emerge in late adolescence or early adulthood. How could those symptoms be caused by developmental events that took place decades earlier? Developmental theories suggest an early disruption causes the brain structure to be disorganized. The start of puberty brings a number of neurological events, including the programmed death of many brain cells, and at that time the abnormalities become critical.
To support developmental theories, there are a number of risk factors for schizophrenia related to critical periods in fetal development, such as:
- Schizophrenia is more common in winter and spring births.
- Children whose mothers experienced famine during the first trimester are more likely to develop schizophrenia.
- Pregnancy and birth complications increase the risk of developing schizophrenia.
However, there is not yet enough evidence that the brains of adults with schizophrenia are disorganized in the ways that developmental theories predict. Also, these theories address the when of schizophrenia’s origin, but not the cause itself.