Schizophrenia is a mental health disorder that causes psychosis with hallucinations and delusions. These and other symptoms can be quite debilitating, and many individuals with schizophrenia are unable to keep a job or to function normally within society, even with treatment. The disorder is associated with a group of genes on different chromosomes. Scientists believe that small changes in several genes interact with each other and with environmental factors to cause the symptoms of schizophrenia. These genes include ABCA13, DGCR2, DGCR8, DRD2, MIR137, NRXN1, and SYN2 (GHR, 2016).
ABCA13 is a gene that codes for proteins that transfer molecules across the cell membrane; it is located on chromosome 7. DGCR2 and DGCR8 are genes on chromosome 22 that are near 22q11. The DRD2 gene, located on chromosome 11, encodes the dopamine receptor D2. Mutations in DRD2 can cause both schizophrenia and a movement disorder called myoclonus dystonia. MIR137 is a micro-RNA that regulates gene expression after transcription; it is located on chromosome 1. NRXN1, on chromosome 2, is the gene that synthesizes a protein on the surface of the neuron that may be important in the regulation of the synapse. SYN2 encodes the protein synapsin II which partially controls the movement of synaptic vesicles and neurotransmitter release. It is expected to play an important part in several neurotransmitter-related disorders including epilepsy, bipolar disorder, and autism, in addition to schizophrenia (GHR, 2016).
There is also a syndrome that combines schizophrenia, immune deficits, heart defects, and cleft palate; called 22q11.2 deletion syndrome, it is caused by a small loss of DNA in that region of chromosome 22. However, the deletion syndrome is responsible for a low percentage of cases of schizophrenia (GHR, 2016).
Psychiatry divides the symptoms of schizophrenia into three categories: positive, negative, and cognitive. Positive symptoms include hallucinations and delusions, confused body motions, and dysfunctional thinking processes. Negative symptoms include lack of facial expressions, lack of vocal tone, problems initiating activities, and reduced speech or movement. Cognitive symptoms can include memory problems, difficulty sustaining attention, and poor decision making (NIMH, 2016). Symptoms may vary, but in order to be diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders V (DSM-5), the person must have “at least two of the following symptoms for a month or more: 1) delusions, 2) hallucinations, 3) disorganized speech, 4) grossly disorganized or catatonic behavior, 5) negative symptoms” (Grohol, 2017). One of the two symptoms must be number one, two, or three.
The primary mode of treatment for schizophrenia is medication. There are several drugs called atypical psychotics which treat the symptoms of schizophrenia and have a reduced incidence of side effects produced by older antipsychotics such as Thorazine and Haldol. However, even the atypical drugs can cause side effects such as weight gain, akathisia, tardive dyskinesia, and extrapyramidal symptoms. Psychotherapy is also helpful in many cases, particularly cognitive behavioral therapy or CBT. Therapy addresses dysfunctional thought patterns as well as helping the individual set up and follow a schedule, since having a routine can increase the individual’s connection with reality.
The incidence of schizophrenia is about 2 out of 10,000 people per year. That is, in a given year, approximately 2 people in every group of 10,000 will be diagnosed with schizophrenia. However, incidence varies from 1.1 to 7 across different countries. Lifetime prevalence of the disorder is also variable, ranging from 2.2 to 8.3 per 1000. According to the National Institutes of Health, ethnic groups with darker skin are more at risk for schizophrenia. It is unknown whether this is primarily due to genetics or if is also determined by environmental factors.