New laboratory research on rodents suggests an elevated stress
hormone in adolescence may be linked to severe mental illness in
adulthood.
Johns Hopkins researchers noted that adolescence is a critical time
for brain development. During this stage, a hormone abundance could
potentially cause genetic changes which could result in severe mental
illness among individuals.
The findings, reported in the journal Science, could have
wide-reaching implications in both the prevention and treatment of
schizophrenia, severe depression and other mental illnesses.
“We have discovered a mechanism for how environmental factors, such
as stress hormones, can affect the brain’s physiology and bring about
mental illness,” said 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.”
“Genetic risk factors in these experiments were necessary, but not
sufficient, to cause behaviors associated with mental illness in mice,”
Sawa said. “Only the addition of the external stressor — in this case,
excess cortisol related to social isolation — was enough to bring about
dramatic behavior changes.”
The investigators not only found that the “mentally ill” mice had
elevated levels of cortisol, known as the stress hormone because it is
secreted at higher levels during the body’s fight-or-flight response,
but that these mice had significantly lower levels of the
neurotransmitter dopamine in a specific region of the brain involved in
higher brain function, such as emotional control and cognition. Changes
in dopamine in the brains of patients with schizophrenia, depression and
mood disorders have been suggested in clinical studies, but the
mechanism for the clinical impact remains elusive.
Source: PsychCentral
http://psychcentral.com/news/2013/01/18/mouse-study-links-teen-stress-to-adult-mental-illness/50505.html