Scientists have discovered a new type of depression: Finding will pave the way for new treatments for 30% of patients who do not respond to drugs
Summary: Certain people with the mental-health disorder may have lower levels of specific receptors, a Japanese study found.
These receptors are important in the release of so-called 'feel-good hormones' such as serotonin and dopamine, the research adds.
As existing antidepressants act on these hormones, this finding may explain why up to 30 percent of patients do not respond to current drugs and could lead to the development of medications that benefit more sufferers.
The researchers, from Hiroshima University, Japan, analysed normal mice and those who had been genetically engineered to express high levels of the protein RGS8.
RGS8 controls a hormone receptor that is involved in emotional responses.
The rodents were placed in a tank of warm water with no exit.
This forced the animals to either swim or 'give up' by becoming immobile, which is considered a sign of depression.
The mice were then euthanised before their brains were examined under a microscope.
Results suggest mice with higher levels of RGS8 swim more and are therefore less depressed.
When such rodents are given the antidepressant drug desipramine, which boosts levels of dopamine and serotonin, their time spent swimming further increases.
Yet giving this drug to non-genetically engineered mice with depression has no effect.
Mr Saito said: 'These mice showed a new type of depression.'
Rodents with higher RGS8 levels have longer hair-like structures, known as cilia, on cells in the region of the brain responsible for emotion.
Cilia on brain cells may be responsible for nerve communication, as well as memory and learning.
The researchers wrote: 'A significant change in cilia length may be associated with the behavioural consequences observed in RGS8 [mice].
They believe the findings, published in the journal Neuroscience, may explain why up to 30 percent of people do not respond to existing antidepressants.
This comes after research released last February suggested eating fruits, vegetables and whole grains slashes people's risk of depression by more than 10 percent.
Following the so-called 'DASH diet' reduces people's likelihood of developing the mental-health disorder by up to 11 percent, a study by Rush University, Chicago, found.
The Diet Intervention for Neurodegenerative Delay (DASH) way of eating is rich in fruits, vegetables, nuts, lean meat, whole grains and fish. It is low in processed foods, sugary drinks, salt and red meat.
People who eat a typical Western diet, which is rich in processed foods and sugar, are more at risk of suffering depression, the research adds.
The researchers add further studies are required to determine the association between diet and mental health, but add simple lifestyle changes may be preferred over medication to control such conditions.
Previous research suggests eating lots of fresh produce benefits people's mental health by improving their moods, giving them more energy and helping them to think clearly.
Source: Mail Online
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