What Causes Schizophrenia?

Brain image, What causes schizophrenia

No one knows exactly what causes schizophrenia, but we do know that it’s a brain disease. The brain is an incredibly complex organ. Connectivity of neurons, brain structure and chemical makeup all intersect, resulting in an organ responsible for every movement, breath, thought and behavior. 

Hundreds of millions of neurons form an intricate pattern to help us think, make decisions, communicate and experience life. For people with schizophrenia, the normal brain processes for some of these functions are impaired or disrupted—resulting in symptoms such as disordered thinking, altered perceptions, delusions and cognitive difficulties. Brain imaging of people with schizophrenia shows some of the abnormalities as reduced gray matter and disrupted neural connectivity

So schizophrenia is clearly a brain disease, but what causes it? Schizophrenia has a strong genetic component. Studies show that if one identical twin has schizophrenia, the other has a 40 to 50 percent chance of developing the disease even if raised separately.

The illness tends to run in families, and although a person may develop schizophrenia without any known relatives with the disease, a closer look at the family tree may reveal possible illnesses that went undiagnosed—an uncle or a cousin said to have behaved strangely or a relative who died by suicide or addiction.  

There is also a genetic link between schizophrenia and bipolar disorder, and mental illness and addiction, so it is not uncommon to have more than one of these illnesses in a family. Psychotic disorders may even exist on a spectrum, similar to the autism spectrum, rather than being discrete illnesses. 

Unfortunately, there is no single schizophrenia gene that could lead us to a definitive treatment or cure. Instead, studies indicate that there may be hundreds of genes involved

Some of the genes implicated are related to the immune system, but the exact nature of the link is unclear. One theory based on researchers’ findings is that these genes may have variations that result in over-pruning of brain synapses—an error of the naturally occurring brain maturation process that removes unneeded connections between neurons to improve brain efficiency. 

This excessive elimination of synapses may explain the impaired thinking, planning and cognition that occurs with schizophrenia. The pruning process typically happens in early adulthood—the same time that schizophrenia typically manifests.

Genetics alone does not explain schizophrenia. Scientists say there is also an environmental component. Contrary to theories that were popular long ago and may perhaps still be prevalent—schizophrenia is not caused by abuse or bad parenting. I can attest that my brother, who had schizophrenia, grew up in a loving, nurturing environment alongside me with no abuse or trauma. 

However, environmental factors can play a role. Genes and the environment can interplay and result in changes in brain development and functioning. Researchers have found that traumatic stress can alter gene expressions that make a person more vulnerable to psychiatric illness. Other studies have found correlations with infection, whether in utero or in life. There is also a link between cannabis use during adolescence and schizophrenia. 

Because we don’t know exactly what causes schizophrenia, we don’t have perfect treatments. Antipsychotics can help with some but not all symptoms, but we don’t know precisely why they work. And unfortunately, antipsychotics don’t work for everyone and they can cause severe side effects, including weight gain (which in turn, increases other health risks) and involuntary movements. 

Right now, these medications are the best treatments we have, and for most, the benefits of the medications outweigh the adverse side effects. But clearly, we need more research and more effective treatments.

And we need compassion. Given that schizophrenia and other mental illnesses are brain illnesses, I have never understood why people blame the sufferers. We see the homeless person muttering to themselves on the street and say, “Why don’t they get a job?” We joke about people ending up in the psych ward or ‘looney bin.’ We speak in hushed whispers about the student admitted to the psychiatric hospital as if it’s a shameful secret rather than an illness. We skip organizing a meal train for the mother whose son was diagnosed with a psychiatric disorder. 

Will this lack of compassion change once we find a definitive cause? I look forward to a world in which researchers find the long-awaited answer to what causes schizophrenia. I believe one day, probably not in my lifetime but someday, we will have safe, effective and compassionate treatment—and ultimately, a cure.

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