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What Causes Schizophrenia?

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  • The exact causes for schizophrenia are unknown, but it is generally accepted that a combination of genetic and environmental factors may increase your risk of developing it
  • The use of drugs has been strongly linked to an increased risk as well

The exact causes for schizophrenia are unknown, but it is generally accepted that a combination of genetic and environmental factors may increase your risk of developing it. The use of drugs has been strongly linked to an increased risk as well.

The Role of Genetics in Schizophrenia

If you have an immediate sibling diagnosed with schizophrenia, there's an 8% chance you may get it, and 12% chance if one of your parents has it. The risk is highest if you have an identical twin with schizophrenia, with a 47% chance.1

Although schizophrenia can run in families, genetics alone do not predict that you will develop schizophrenia. There are many people who have one or more relatives affected with schizophrenia, but who do not develop the disease themselves. Actually, scientists believe that an interaction between genes and environment must occur first.2

Environmental Factors That May Influence Your Risk

Several external factors have been linked to an increased risk of schizophrenia, including:3,4

  • Exposure to viral infections while inside the mother's womb
  • Viral exposure during infancy
  • Low oxygen levels during birth
  • Physical or sexual abuse during childhood
  • Life events, such as early parental loss or divorce
  • Drug abuse

Stress during pregnancy has also been linked to higher risks of schizophrenia once the child grows.5 Other seemingly unrelated factors, such as what season you were born and the location you grew up in, may play a role.6

Research suggests that you have a 10% higher risk of developing schizophrenia if you were born in the winter months in the Northern hemisphere. If you were born and raised in an urban environment, you have a 50% higher risk of developing schizophrenia.

Even Your Brain's Physical Properties May Play a Role in Schizophrenia

Since schizophrenia affects the way people view reality, it's natural that scientists compare the physical differences of a healthy person’s brain and that of a person with schizophrenia. Studies have found that chemical interactions between dopamine, glutamate and other organic chemicals may play a role in the development of schizophrenia. Malfunctions during the production of these chemicals may increase your risk as well.7

Even the structure of your brain may play a role in the development of schizophrenia. Brain ventricles, which are cavities filled with fluid that help keep the central nervous system healthy,8 are found to be larger in persons with schizophrenia, suggesting a deficit in total brain tissue volume. The brain of someone with schizophrenia is also found to have a few areas that have less or more activity compared to a healthy brain.

Recreational Drug Use Has Been Linked to an Increased Risk for Schizophrenia at Later Ages

Recreational drug use at a young age has been linked with an increased risk for schizophrenia during the later years of life, especially among regular cannabis users.

In a study released by The British Medical Journal, over 50,000 soldiers from the Swedish Army were initially interviewed about their drug use, and were then regularly followed up. The study found that soldiers who heavily used recreational cannabis at the age of 18 had a 600% higher risk of being diagnosed with schizophrenia over the next 15 years than those who didn't consume it.9,10

In a separate study conducted in New Zealand, teenagers who used cannabis by the age of 15 were 300% more likely to develop schizophrenia.11 It's inferred that your brain is very vulnerable during its development in your teenage years, which may explain the drastic risk increase.

While there is evidence linking schizophrenia and drug use, it is not accepted as an "official" cause of schizophrenia, as conducting official studies that encourage drug use on a person at risk of schizophrenia is very unethical.

Instead, researchers track participants over a long period time by conducting cohort studies and regularly gathering information from participants.12 But based on the information provided, it's clear that avoiding recreational drug abuse can help lower your risk for developing schizophrenia.

In addition, note that these findings came from recreational cannabis users who have consumed high amounts over a long period of time. Controlled use of marijuana in a medical setting may actually be helpful for you, as researchers have found that it may help treat chronic nerve pain and promote better sleep.


Schizophrenia: Introduction

What Is Schizophrenia?

Schizophrenia Types

Schizophrenia in Children

Schizophrenia Causes

Is Schizophrenia Hereditary?

Schizophrenia Symptoms

Schizophrenia Diagnosis

Schizophrenia Treatment

Famous People With Schizophrenia

Schizophrenia Prevention

Living With Schizophrenia

Schizophrenia FAQ

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Is Schizophrenia Hereditary?

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