In a study on mice, Johns Hopkins researchers established a link between elevated levels of the stress hormone cortisol during the teen years, and genetic changes that, in young adulthood, cause severe mental illness in those predisposed to mental illness.
The researchers noted that the teen years are a critical time for brain development. The abundance of cortisol could potentially cause genetic changes, which then could result in severe mental illness.
The study was performed on mice, and according to study leader Akira Sawa, M.d., Ph.D., a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine, “We’ve shown in mice that stress in adolescence can affect the expression of a gene that codes for a key neurotransmitter related to mental function and psychiatric illness. While many genes are believed to be involved in the development of mental illness, my gut feeling is environmental factors are critically important to the process.” The researchers simulated in the mice the social isolation associated with the difficult teen years and found that isolating healthy mice had no effect on their behaviors but when mice known to have a genetic predisposition to characteristics of mental illness were similarly isolated, they exhibited behaviors associated with mental illness.
In addition to higher levels of cortisol, the researchers found the predisposed mice had significantly lower levels of the neurotransmitter dopamine in the area of the brain involved in higher brain function, such as emotional control and cognition. Previous studies have found changes in dopamine levels in the brains of patients with schizophrenia, depression and mood disorders.
Sawa and his research team indicated that these findings highlight the need for better preventive care in teenagers who have mental illness in their families. Preventive measures could include efforts to protect the teens from social stressors, such as neglect or abuse.