People affected by alcoholism have statistically increased chances of developing the severe mental illness schizophrenia. Conversely, people affected by schizophrenia have statistically increased chances of developing diagnosable symptoms of alcoholism. Current scientific evidence has linked alcoholism to schizophrenia through variations in a single human gene, known as rs6265. In a study published in September/October 2014 in the journal Alcohol and Alcoholism, a group of Australian researchers assessed the influence of this gene. The researchers concluded that this gene and a second neighboring gene have a unique ability to increase the alcoholism risks of people affected by schizophrenia.
Alcoholism and Schizophrenia
Alcoholism is a subtype of a larger condition called alcohol use disorder. Affected individuals have a physical dependence on alcohol that stems from the chemical influence of repeated alcohol exposure in the brain’s pleasure center. Other distinguishing characteristics of alcoholism include recurring cravings for alcohol, an impaired ability to control drinking participation or amount of alcohol intake, significant increases in the amount of alcohol it takes to get drunk, exposure to withdrawal symptoms when alcohol intake levels decline and continued, excessive alcohol consumption after strongly negative drinking outcomes occur.
Schizophrenia is an incapacitating mental illness most closely associated with paranoid trains of thought and other forms of clearly delusional thinking, as well as with sound-based hallucinations and other types of hallucinations. Additional symptoms of the disorder include strangely organized thinking, an unusual lack of emotional responsiveness and poor control of higher-level mental skills such as decision-making, logical thinking and the ability to maintain a focus of attention. Roughly one out 100 American adults has schizophrenia. Most cases emerge in the 15-year window between the ages of 16 and 30, although cases in younger and older individuals also sometimes occur.
Alcoholism and schizophrenia often overlap in the same individual and function as comorbid conditions. This means that a person affected by alcoholism and schizophrenia has a considerably worse state of health than a person who only has alcoholism or only has schizophrenia. In addition to genetics, recognized pathways for the connection between the two conditions include the tendency of people with severe mental illnesses to use alcohol as a misguided form of self-administered treatment, the potential for excessive alcohol use to contribute to a serious worsening of existing schizophrenia symptoms and the potential for excessive alcohol use to contribute to a mental health environment that favors the initial development of schizophrenia symptoms. Mental health experts and addiction specialists use the term dual diagnosis to identify people simultaneously affected by alcoholism and schizophrenia, or any other combination of a diagnosable substance problem and a diagnosable mental illness.
Exploring the Genetic Link
In the study published in Alcohol and Alcoholism, researchers from Australia’s Queensland University of Technology, University of Queensland and Royal Brisbane and Women’s Hospital used an analysis of 848 adults to explore the genetic connection between alcoholism and schizophrenia. Of these individuals, 392 had a diagnosis of schizophrenia, while another 231 were unaffected by schizophrenia but had an alcoholism diagnosis. The remaining 225 study participants did not have schizophrenia or alcoholism. The researchers used detailed testing to isolate the alcoholism- and schizophrenia-related impact of two different variations of the rs6265 gene, as well as the impact of a single variation of a neighboring gene known as rs7103411. They targeted rs6265, in particular, because previous research had produced conflicting points of view on the gene’s role in the simultaneous manifestation of alcoholism and schizophrenia.
After completing their analysis, the researchers concluded that all of the genetic variations under consideration contribute to the risks that a person diagnosed with schizophrenia will develop diagnosable symptoms of alcoholism. This contribution is particularly clear in men affected by schizophrenia. The researchers also concluded that the combination of variations in both of the targeted genes increases the odds that a schizophrenic person diagnosed with alcoholism will take part in particularly dangerous or hazardous behavior after consuming alcohol.
When the study’s authors looked at the role of the two targeted genes in the alcoholism risks of people unaffected by schizophrenia, they concluded that the genes do not have the same influence on the risks for diagnosable alcohol problems. This means that the genetic variations under consideration appear to exert their effect only in cases of overlapping or comorbid alcoholism and schizophrenia.