What Causes Schizophrenia?

The Struggles of Schizophrenia - Hallucinations

The very first time I heard the word 'schizophrenia' was seven years ago when my parents told me that one of our close relatives had been diagnosed with it. As an unaware ten year old, I didn't really know or care to know what this meant, I just accepted it and moved on. This topic of conversation was recently brought up again at a family gathering, where I discovered that schizophrenia is actually very common and often inherited in my family. This prompted a spark of curiosity. What even is schizophrenia? I became interested in researching causes and symptoms of it, as well as how it affects individuals because it turned out to be a larger part of my life than I had previously thought. Here is what I discovered in the process...

Schizophrenia is a chronic mental disorder that is associated with changes in the structure and function of the prefrontal and medial temporal lobe, the interconnected regions of the brain that are responsible for our decision making, as well as our ability to organize thoughts and control impulses. Though schizophrenia is still a partial medical mystery, over 1% of the population is affected by it (equating to roughly 20 million people worldwide). 

Share of Population with Schizophrenia as of 2017

Symptoms often develop between the ages of 12 and 40 and individuals are typically diagnosed between the ages of 17 and 30. Early traits (most often observed in teenagers) include difficulty concentrating, aggression, social withdrawal, and restlessness. As time goes on and the severity of the illness increases, people may begin to hallucinate, hear voices, and feel that others are controlling their thoughts. These episodes tend to become more frequent and often frighten the person, leading to a flawed perception of reality, isolation, behavioral abnormalities and emotional instability. 

Intrusive Thoughts and Voices - Art by Alberto Ruggieri 

But, what specifically causes schizophrenia? Well, after extensive research, scientists were able to conclude that this illness actually has a multitude of potential causes. Genetics, for starters, plays a very large role in the inheritance of schizophrenia. In fact, studies show that someone is 6 times more likely to be schizophrenic if they have a close relative who suffers from the disorder as well. Faulty intrauterine environments, such as malnutrition or exposure to viruses, have also been linked to an increased risk in adolescent schizophrenia. Lastly, a fluctuation in the abundance of certain inhibitory neurotransmitters (such as dopamine) and major substrates (such as glutamine) often lead to protein imbalances that cause schizophrenia and other mental illnesses. For example, mTOR, a protein found in the PI3K pathway, controls most mammalian catabolic and anabolic processes and is often regulated improperly in schizophrenic individuals, leading to irregular stimulation. 

The mTOR Pathway in Schizophrenia

Factors such as irregular mTOR pathways are generally difficult to recognize in individuals, but with the help of brain mapping, neurologists have found other ways to identify schizophrenia. Researchers have discovered that scanning the levels of a patients cortical gray matter is actually a very promising way to indicate whether or not they are schizophrenic. As represented by the figure below, schizophrenic individuals tend to have an increased rate of gray matter loss as opposed to unaffected individuals. Microglia, non-neuronal brain cells that function as active immune defense, are often the main promoters of gray matter loss through atypical phagocytosis of stressed neurons, pruning of synapses, and release of neurotropic factors (NTF's).  

Rate of Gray Matter Loss in Schizophrenic Patients

Unfortunately, there is no current cure for this disorder, but that does not mean all hope is lost. Antipsychotic medication and therapy (such as cognitive behavioral therapy) are effective and fairly common forms of treatment for individuals suffering from schizophrenia.