Is mental illness hereditary? Can it be passed down through the next generation?

There are currently many causes of mental illness, some of which are related to genetics. If there are cases of mental illness in the family, then the descendants may have a certain probability of suffering from mental illness. Family members who have a history of mental illness do not need to be too nervous, but should find out whether the mental illness can be inherited.

1. Is mental illness hereditary?

There are many types of mental illness. Except for a small number of temperamental mental illnesses and mental retardation that have clear genetic conditions, the rest are caused by multiple factors such as physical, psychological and environmental factors. Research has shown that the proportion of the general population suffering from schizophrenia is 0.3%, and the blood relatives of schizophrenia patients are more likely to suffer from the disease than the general population. According to current research results, the incidence rate of schizophrenia among siblings of patients with schizophrenia is 7%-15%. If one parent is ill, the incidence rate of their children increases to 16%. If both parents suffer from the disease, the incidence rate of their children is 40%-68%. As for periodic bipolar disorder, the incidence rate for the general population is about 0.4%, the incidence rate for fraternal twins is 26.3%, and the incidence rate for identical twins is 95.7%. So we have to take genetic influences into account.

2. Can mental illness be inherited from one generation to the next?

In general, various mental illnesses have a genetic predisposition. Mild mental illnesses, such as neurasthenia, hysteria, obsessive-compulsive disorder, phobia, and anxiety disorders, have a lower chance of being inherited, while severe mental illnesses, such as schizophrenia and manic-depressive disorder, are most likely to be inherited. A grandfather's illness may be passed on to his grandson. Through a detailed investigation of 4-5 generations of direct and collateral relatives of hospitalized schizophrenia patients, the prevalence rate was 7-8 times higher than that of the general population. The results of investigations in other regions in China and abroad were roughly the same.

Moreover, the more people with the disease in a family and the closer the blood relationship to the sick person, the greater the chance of getting the disease. Taking schizophrenia as an example, if one parent is ill, the chance of their children being ill is about one in four, which means that one in four children may be ill. If both parents are ill, their children have more than a 50% chance of developing the disease.

Blood relatives of schizophrenia are not only susceptible to schizophrenia, but also to other mental illnesses, such as mental retardation and affective psychosis. Judging from the symptoms and course of events, the younger generation tends to develop the disease earlier than the previous generation, and the condition tends to worsen.

3. Is acquired mental illness hereditary?

The scope of mental illness is very broad, and it is impossible to say in general whether it is a hereditary disease or not. According to clinical research data, some mental illnesses are hereditary. For example, phenylketonuria, Down syndrome and mental retardation, their basic causes are genetic factors. Their inheritance is caused by chromosomal aberrations or hereditary metabolic defects.