Health researchers try to blame depression on genes

It's a preposterous idea, actually. You'd have to be insane to think our evolutionary path somehow favored genes that actually cause mental depression.

• A newly discovered gene mutation may make some people more vulnerable to depression.
• If confirmed by larger studies, the finding may shed new light on depression, which affects almost 19 million Americans per year, according to the National Institute of Mental Health.
• Several gene mutations have been linked to depression before now.
• The mental illness may be caused by a complex mix of genetic and environmental factors.
• The latest mutation was identified by scientists at the Duke University Medical Center.
• Marc Caron, PhD, and James B. Duke, professor of cell biology, led the study.
• It appears in the online edition of the journal Neuron.
• Earlier this year, they noticed that variations of a certain enzyme called tryptophan hydroxylase-2 (TPH2) affected serotonin levels in mice.
• When serotonin levels are low, communication among brain cells suffers.
• With that in mind, the researchers screened the genes of 48 people from another Duke study, searching for mutations that explain TPH2's variations.
• They studied the genes of 87 people with major depression and found that more than 10% (nine people) carried the mutation.
• The mutation was not found among people diagnosed with bipolar disorder.
• Of the nine people with the mutation, seven had a family history of mental illness or drug/alcohol abuse, six had tried to commit suicide or shown suicidal behavior, and four had generalized anxiety symptoms.
• The nine participants also had a hard time taking depression medications called selective serotonin reuptake inhibitors (SSRIs), such as Prozac.
• One showed signs of generalized anxiety, and the other two had mild depression and family histories of mental illness or drug and alcohol abuse.