March 26, 2014
News Review From Harvard Medical School – Gene May Explain Increased Risk for Depression
People who have a variant gene and experienced a high level of stress were more likely to experience depression, a new study suggests. Researchers looked at the genes of nearly 2,361 white people from the United Kingdom and Hungary. They asked them about past and recent life events. These included childhood abuse or neglect, financial problems and illnesses. The participants were also assessed for current depression and anxiety. The researchers found that people with genetic variations in a brain chemical called galanin were more likely to be depressed and anxious after stressful life events. Galanin seems to have a role in pain, sleeping, waking mood and blood pressure. It's suspected to also play a role in stress and anxiety disorders. The results may help develop new drugs to treat depression and anxiety. The journal Proceedings of the National Academy of Sciences published the study. HealthDay News reported on it March 25.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
The results of this study add to the rapidly growing knowledge of how life events and our genetic makeup might influence the risk of mental health disorders, such as depression. Life stress impacts each of us differently. Finding the genes that influence how life stress increases the risk of depression is a key to developing new and better treatments.
These researchers looked at depression risk related to variations in genes that regulate the production and function of galanin. Galanin is a small protein produced in the brain. Galanin appears to work alongside two other brain chemicals, serotonin and norepinephrine. These two chemicals play an important role in depression.
The researchers found significant genetic variations that controlled galanin brain activity. And difference in the genes influenced the brain level and activity of galanin in response to life stress, both in childhood and later in life. So, these genetic variations may help predict which people are most vulnerable to life stress. And which people are therefore more likely to develop depression.
Some diseases are caused by a mutation in a single gene. Huntington's disease is an example. If you inherit the mutated gene, you will get the disease. But the galanin gene is only one of many genes that likely play important roles in depression.
Indeed, most experts believe that depression and other psychiatric disorders develop because of the interplay between multiple genes. Each gene exerts relatively small effects. This makes finding the responsible genes harder. That's because there are multiple small targets rather than a single relatively large one.
It gets even more complicated. In addition to genes and life events, gender also plays a big role in depression risk. Women are twice as likely as men to develop depression.
What Changes Can I Make Now?
Today depression remains a clinical diagnosis. That means it's based on symptoms. There is no blood test, genetic test or scan to diagnose depression.
A good screening tool for depression is to ask yourself these two questions:
- Over the past two weeks, have you felt depressed or hopeless?
- In the same period, have you felt little interest or pleasure in your usual activities?
If the answer to either of these is yes, seek help. Start with your primary care doctor or reach out to a mental health professional.
Depression isn't the same in everyone. And feeling sad might not be the major symptom.
Here are some of the other symptoms:
- Trouble concentrating or remembering things
- Sleep changes (can't sleep or sleep too much)
- Anger or irritability
- Appetite or weight changes (can be either more or less)
- Reckless behavior, such as excessive alcohol use or reckless driving
- Feeling worthless
- Thinking about harming yourself
There may be reasons other than depression for these symptoms. But depression is one of the most common causes.
What Can I Expect Looking to the Future?
Studies such as this one only show an association between a genetic variant, life stress and depression risk. It does not prove the gene is directly responsible.
Large studies of thousands of participants will be needed to find reliable genetic patterns that indicate definite risk.