In some cases, this disorder can affect a persons ability to have a fulfilling social life and they may also have trouble forming bonds or relationships with others. Schizoaffective disorder is also more likely to occur in women and begins at a young age. Substance use disorder
A clear causal connection between substance use and psychotic spectrum disorders, including schizoaffective disorder, has been difficult to prove. In the specific case of cannabis (marijuana), however, evidence supports a link between earlier onset of psychotic illness and cannabis use. The more often cannabis is used, particularly in early adolescence, the more likely a person is to develop a psychotic illness, with frequent use being correlated with double the risk of psychosis and schizoaffective disorder. A 2009 Yale review stated that in individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. While cannabis use is accepted as a contributory cause of schizoaffective disorder by many, it remains controversial, since not all young people who use cannabis later develop psychosis, but those who do use cannabis have an increased odds ratio of about 3. Certain drugs can imitate symptoms of schizophrenia (which is known to have similar symptoms to schizoaffective disorder). This is important to note when including that substance-induced psychosis should be ruled out when diagnosing patients so that patients are not misdiagnosed.
Emil Kraepelin introduced the idea that schizophrenia was separate from mood disorders after observing patients with symptoms of psychosis and mood disorder, over a century ago, in 1898. This was a time before genetics were known and before any treatments existed for mental illness. The Kraepelinian dichotomy was not used for DSM-I and DSM-II because both manuals were influenced by the dominant psychodynamic psychiatry of the time, but the designers of DSM-III wanted to use more scientific and biological definitions. Consequently, they looked to psychiatrys history and decided to use the Kraepelinian dichotomy as a foundation for the classification system. The Kraepelinian dichotomy continues to be used in DSM-5 despite having been challenged by data from modern psychiatric genetics for over eight years, and there is now evidence of a significant overlap in the genetics of schizophrenia and bipolar disorder. According to this genetic evidence, the Kraepelinian categorical separation of mood disorders from schizophrenia at the foundation of the current classification and diagnostic system is a mistaken false dichotomy.The dichotomy at the foundation of the current system forms the basis for a convoluted schizoaffective disorder definition in DSM-IV that resulted in excessive misdiagnosis. Real life schizoaffective disorder patients have significant and enduring symptoms that bridge what are incorrectly assumed to be categorically separate disorders, schizophrenia and bipolar disorder. People with psychotic depression, bipolar disorder with a history of psychosis, and schizophrenia with mood symptoms also have symptoms that bridge psychosis and mood disorders.