Research suggests that schizophrenia runs in families, and consequently, individuals with a first-degree relative (for example, a parent, brother, or sister) or a second-degree relative (a grandparent, aunt, or uncle) with schizophrenia are at an increased risk. Despite the genetic risk, researchers believe that genes alone are not enough to cause the disorder.

It is more likely that genes interact with environmental factors, such as exposure to viruses or malnutrition before birth or problems during birth, and psychosocial factors, such as stressful environmental conditions. Any one of these conditions may to trigger the condition. This means that if a person who has a vulnerability to developing schizophrenia engages in alcohol and drug abuse, this behavior may interact with the vulnerability and result in the development of the disorder.

Some drug abuse may produce symptoms that look like schizophrenia. For example, bingeing on cocaine or methamphetamine can result in exaggerated irritability, restlessness, and paranoia. It's not unusual for drug binges to result in paranoid psychosis, in which the individual loses touch with reality and imagines hearing things that aren't there (known as auditory hallucinations). The symptoms of acute drug-induced psychosis are similar to the symptoms that someone with schizophrenia experiences.

Although the relationship between drug addiction and schizophrenia may not be crystal clear, it is important to consider other negative consequences of addiction to such drugs as cocaine and marijuana. By definition, when people become "addicted" to a drug, they develop a tolerance, thus requiring ever greater amounts to experience the desired high.

The increased heavier and heavier use of the drug can have a significant impact on overall health, including mental health. Heavy marijuana use, for example, has been associated with depression, anxiety, and personality disturbances and can affect someone's ability to learn and retain information. Overall, drug use is also associated with absenteeism, poor work, poor academic performance, and family disruption.

References
(To view, roll mouse over the "References" heading; to hide, click on the heading)