From the Guidelines
The primary risk factors for developing schizophrenia, ranked by their relative impact, are genetics, family history, and prenatal complications, with genetic factors accounting for approximately 80% of susceptibility, as noted in the most recent study 1. The risk factors for schizophrenia can be broken down into several key categories, including:
- Genetic factors: Having a first-degree relative with schizophrenia is the strongest risk factor, increasing risk by about 10% 1.
- Prenatal complications: Maternal infection, malnutrition, or stress during pregnancy rank next in significance, as they can impact fetal brain development and increase the risk of schizophrenia 1.
- Environmental factors: Cannabis use, particularly heavy use during adolescence, childhood trauma, and urban upbringing are also significant risk factors for developing schizophrenia 1.
- Birth complications: Oxygen deprivation, low birth weight, and premature birth contribute meaningfully to risk, as they can impact brain development and increase the risk of schizophrenia 1.
- Social factors: Migration, social isolation, and lower socioeconomic status present moderate risk, as they can impact access to healthcare and increase stress, which can contribute to the development of schizophrenia 1. It's essential to note that these risk factors interact in complex ways, with genetic vulnerability often requiring environmental triggers to manifest as clinical schizophrenia, reflecting the disorder's multifactorial nature, as discussed in the American Psychiatric Association's practice guideline for the treatment of patients with schizophrenia 1. Genetic factors are the most significant risk factor, and identifying individuals with a high genetic risk can help inform prevention and treatment strategies, as recommended by the American Psychiatric Association 1. Overall, understanding the risk factors for schizophrenia is crucial for developing effective prevention and treatment strategies, and genetic factors, family history, and prenatal complications are the primary risk factors that should be considered, as supported by the most recent and highest-quality study 1.
From the Research
Risk Factors for Schizophrenia
The risk factors for schizophrenia can be ranked based on the available evidence as follows:
- Genetic factors: Having a first-degree relative with schizophrenia is a significant risk factor, with a 13% probability of developing the condition if one parent is affected, and over 20% if both parents are affected 2.
- Environmental factors: Various environmental factors, including urbanicity, migration, cannabis use, childhood traumas, infectious agents, obstetrical complications, and psychosocial factors, have been associated with an increased risk of developing schizophrenia 3, 4.
- Perinatal risk factors: Complications during pregnancy and delivery, such as obstetrical complications, can increase the risk of developing schizophrenia 3, 4.
- Substance abuse: Cannabis abuse, in particular, has been linked to an increased risk of developing schizophrenia, especially during adolescence 3, 4.
- Traumatic events: Traumatic events during childhood can also contribute to the development of schizophrenia 4.
- Psychosocial factors: Socio-demographic factors, such as social stress and adversity, can also play a role in the development of schizophrenia 3, 5.
Interaction of Risk Factors
It is essential to note that the development of schizophrenia is a complex process involving the interaction of multiple risk factors, including genetic, environmental, and psychosocial factors 5, 4. The timing and cumulative effect of these risk factors can influence the onset, development, and relapse risk of the disease 4.
Ranking of Risk Factors
Based on the available evidence, the ranking of risk factors for schizophrenia can be summarized as:
- Family history of schizophrenia (genetic factor) 6, 2
- Environmental factors (urbanicity, migration, cannabis use, etc.) 3, 4
- Perinatal risk factors (obstetrical complications, etc.) 3, 4
- Substance abuse (cannabis abuse, etc.) 3, 4
- Traumatic events (childhood traumas, etc.) 4
- Psychosocial factors (socio-demographic factors, etc.) 3, 5