"The causes of schizophrenia are not fully known. However, it appears that schizophrenia usually results from a complex interaction between genetic and environmental factors.
Genetic causes of schizophrenia
Schizophrenia has a strong hereditary component. Individuals with a first-degree relative (parent or sibling) who has schizophrenia have a 10 percent chance of developing the disorder, as opposed to the 1 percent chance of the general population.
But schizophrenia is only influenced by genetics, not determined by it. While schizophrenia runs in families, about 60% of schizophrenics have no family members with the disorder. Furthermore, individuals who are genetically predisposed to schizophrenia don’t always develop the disease, which shows that biology is not destiny.
Environmental causes of schizophrenia
Twin and adoption studies suggest that inherited genes make a person vulnerable to schizophrenia and then environmental factors act on this vulnerability to trigger the disorder.
As for the environmental factors involved, more and more research is pointing to stress, either during pregnancy or at a later stage of development. High levels of stress are believed to trigger schizophrenia by increasing the body’s production of the hormone cortisol.
Research points to several stress-inducing environmental factors that may be involved in schizophrenia, including:
Prenatal exposure to a viral infection
Low oxygen levels during birth (from prolonged labor or premature birth)
Exposure to a virus during infancy
Early parental loss or separation
Physical or sexual abuse in childhood
Abnormal brain structure
In addition to abnormal brain chemistry, abnormalities in brain structure may also play a role in schizophrenia. Enlarged brain ventricles are seen in some schizophrenics, indicating a deficit in the volume of brain tissue. There is also evidence of abnormally low activity in the frontal lobe, the area of the brain responsible for planning, reasoning, and decision-making.
Some studies also suggest that abnormalities in the temporal lobes, hippocampus, and amygdala are connected to schizophrenia’s positive symptoms. But despite the evidence of brain abnormalities, it is highly unlikely that schizophrenia is the result of any one problem in any one region of the brain."
References: Melinda Smith, M.A., and Jeanne Segal, Ph.D.
Resources & References
Basic Facts About Schizophrenia (PDF) – This 40-page booklet covers the most frequently asked questions about schizophrenia, including what it’s like and how families can help. (British Columbia Schizophrenia Society)
Understanding Schizophrenia and Recovery – Covers what people with schizophrenia and their families need to know about schizophrenia and its treatment. (National Alliance on Mental Illness)
Symptoms and early warning signs of schizophrenia
Schizophrenia – Provides a comprehensive overview discussing causes, symptoms, diagnosis, treatment and current research on schizophrenia. (National Institute of Mental Health)
Schizophrenia in Children – Describes symptoms in children, which may be different from those in adults. (American Academy of Child and Adolescent Psychiatry)
The First Signs of Schizophrenia – Read through personal stories, offered by both people with schizophrenia and their loved ones, describing the early signs and symptoms they observed. (Schizophrenia.com)
Types of schizophrenia
Paranoid Schizophrenia – Learn about the most common subtype of schizophrenia, including typical signs and symptoms such as paranoid delusions. (Mayo Clinic)
Catatonic Schizophrenia – Overview of the signs and symptoms of catatonic schizophrenia, as well as its causes and effects. (Mayo Clinic)
Disorganized Schizophrenia – Guide to disorganized schizophrenia’s signs and symptoms, such as disorganized thinking, disorganized behavior, and flat affect. (Mayo Clinic)
Causes of schizophrenia
Possible Causes of Schizophrenia – Reviews the possible causes of schizophrenia, including biological, psychological, and social factors. (Schizophrenia Fellowship of NSW)
What Causes Schizophrenia? – Covers the combination of causes involved in schizophrenia, including genes, brain chemistry, and brain structure. (National Institute of Mental Health)
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