In a new study, researchers found a possible mechanism that may explain why depression drugs may not work for some patients.
The findings may help develop better treatment and therapy for people suffering from depression.
The research was conducted by Salk Institute researchers.
A major depressive disorder is a persistent feeling of sadness or a lack of interest in outside stimuli. People may change their appetite, sleep patterns, body clock, and interests in daily activities.
If left untreated, the disease can have fatal results.
According to recent research, more women experience major depressive disorder than men. This may be because depression often co-occurs with other illnesses and mental conditions.
For women, pregnancy, childbirth, and menopause may be linked to higher risks of depression.
Previous studies have shown that selective serotonin reuptake inhibitors (SSRIs) are the most common drugs for major depressive disorder.
SSRIs can increase levels of the neurotransmitter serotonin at neuron connections and help reduce the symptoms of many patients with depression.
However, it is unknown why the treatment does not work in nearly 30% of patients with the condition.
In the current study, the team discovered the changes in neurons may explain it.
They examined a large-scale clinical study of 800 patients with depression and selected the most extreme effective cases of SSRI treatment and patients who saw no effect.
They found that SSRI non-responders had increased receptors for serotonin in the brain, which made the neurons hyperactive in response to serotonin.
They observed a difference in how the neurons responded based on their shape.
Neurons from SSRI non-responders had longer neuron projections than the best responders. The SSRI non-responders also had low levels of key genes involved in forming neuronal circuits.
The team suggests that their findings contribute to a new way of examining, understanding, and addressing depression.
They also suggest that other drugs like serotonergic antagonists may be used as additional options for some depression patients.
In the future, the team will examine genes to better understand the genetics of SSRI non-responders.
The lead author of the study is Salk Professor Rusty Gage, president of the Institute, and the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Disease.
The study is published in Molecular Psychiatry.
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