Substance Use and Schizophrenia

There has long been a recognized association between marijuana and schizophrenia, in part due to studies which have attempted to link the two. The causal relationship between drug use and mental illness has been a subject for debate for eons. While many people who abuse mind altering substances have co-occurring mental health disorders, there is evidence which suggests that some mental health disorders may actually be caused by the use of drugs or alcohol.

It goes without saying, it is a difficult task to determine whether or not someone developed a mental health problem by using drugs and/or alcohol, or the drugs and alcohol actually caused the mental health disorder. There has been a large amount of research to determine the link, if one exists, between substance use and the risk of developing psychiatric disorders. At times, such research has been both controversial and contradictory, which is why a team of researchers in Denmark put themselves to the task of making sense of the possible link, MNT reports. The findings were published in The Lancet.

Unsurprisingly, the researchers found that substance abuse of any kind heightened the risk of developing schizophrenia, according to the article. Below you can find a breakdown of the increased risks:

• Cannabis (5.2 times greater risk)
• Alcohol (3.4 times)
• Hallucinogens (1.9 times)
• Sedatives (1.7 times)
• Amphetamines: 1.24 times
• Other substances (2.8 times)

The researchers came to their findings by looking at data from 3,133,968 individuals born in Denmark between 1955-1999, the article reports. The researchers write:

"We present a large scaled population-based cohort study analyzing a wide variety of substances. Our results illustrate a robust association between almost any type of substance abuse and an increased risk of developing schizophrenia later in life." 

While the findings were insightful, the researchers believe that it may be “impossible to prove whether the abuse caused the schizophrenia or vice versa.”