Sustained stress over a period of time can play havoc with our health, we all know that. It reduces our ability to function effectively and eventually takes its toll on the body. Stress is involved to some extent in every single ailment or disease known to man. Now we know it can shrink the brain too.
There has already been an association seen between stress and smaller brain size. In a study published in January in the journal Biological Psychiatry, researchers found that people who were under stress were found to have less grey matter in the prefrontal cortex part of the brain. Now, a recent study published in August in the journal Natural Medicine, a “direct connection” has been identified between anxiety, major depression disorder and a reduction in brain size.
Circuits normally involved in emotion, as well as cognition, are disrupted
In the most recent study, researchers from Yale University are the first to discover the genetic transcription that actually causes the brain to shrink. They analyzed the brain tissue of both depressed and non-depressed patients to identify differences in gene activation. What they found was that in the brains of people who were depressed, there were lower levels of expression genes that are needed for the function and structure of the brain.
“We wanted to test the idea that stress causes a loss of brain synapses in humans” said Ronald Duman, senior author on the study and Professor of Psychiatry and Professor of Neurobiology and Pharmacology.
“We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated”.
Transcription Factor GATA1
According to Lead author H. J. Kang, at least five of the genes could be regulated by a single transcription factor called GATA1 as laboratory studies have indicated that this transcription factor is involved both in the loss of brain connections and in the symptoms of depression.
Professor Duman reckons that identifying variations in GATA1 could also identify people who are more at risk from depression or who are more sensitive to the effects of stress and more effective treatments can be found.
“We hope that by enhancing synaptic connections, either with novel medications or behavioral therapy, we can develop more effective antidepressant therapies” said Duman.
This study was funded by the National Institutes of Health and the Connecticut Department of Mental health and Addiction Services.
Healthy individuals under stress
Earlier in the year, a study also by researchers from Yale, found that stress can reduce brain size and brain function in individuals who were otherwise completely healthy. The researchers asked 103 healthy participants (after prescreening for substance abuse, head injuries and other factors that might have an impact on the brain) to take part in a cumulative adversity interview that was designed to estimate the level of stress in their lives. Participants were asked questions about recent traumatic events such as divorce, financial problems, and other stress inducing factors.
MRI scans confirmed reduction
After the interviews, participants underwent MRI (Magnetic Resonance Imaging) scans to see how the results of the interviews compared to the brains of these individuals. The scans revealed that those who were under high levels of stress also had a reduction in brain tissue in the prefrontal cortex part of the brain.
This study was the first to show the effect of stress on the brain in otherwise healthy individuals. Bearing in mind that these individuals were not suffering from any depressive illness the findings are significant as it could pinpoint individuals who may in the future be at risk of a mental health problem.
“The accumulation of stressful life events may make it more challenging for these individuals to deal with future stress, particularly if the next demanding event requires effortful control, emotion regulation, or integrated social processing to overcome it” said Emily Ansell, assistant professor of psychiatry at the Yale School of Medicine and author of the study.
“These key regions are the regions we believe regulate our emotions, help us control our impulses and help us process our daily experience. They also control our physiology. These regions have implications for long-term health.”
Back in January, researchers from Yale found that people with no mental health problems but who were experiencing a significant amount of stress, had smaller brains than those who had less stress in their lives. Then another study identified what may be the genetic triggers that are involved in the loss of connections between neurons and a reduction in brain size. The implications are enormous.
If it is possible to identify those who are more at risk of a major depressive disorder or more susceptible to the effects of stress, then it may be possible to prevent problems too, either by taking steps to reduce the amount of stress or by earlier intervention with therapy.