Taste may give a clue in how to treat depression

Researchers in the UK have found that taste tests could determine the cause of depression in patients and also indicate which is the best drug to treat the illness.

The researchers from Bristol University have discovered that taste perception is altered by the same brain chemicals that effect depression -- serotonin and noradrenaline.

It appears that the two brain chemical affect taste differently, increased serotonin levels improves sensitivity to sweet and bitter tastes and increased noradrenaline improves sensitivity to bitter and sour tastes.

They say our ability to recognise certain tastes can be improved by administering drugs usually given for depression.

This they say makes it easier to know which is causing the imbalance in depressed patients and this knowledge can then be used to determine which is the most suitable drug to treat the illness.

For the study they gave healthy volunteers antidepressant drugs that increase levels of the neurotransmitters serotonin and noradrenaline.

Three drugs were given, SSRI (serotonin specific reuptake inhibitor) to raise serotonin levels; NARI (noradrenaline reuptake inhibitor) to raise noradrenaline levels (another neurotransmitter important in depression, and also found in taste buds); and an inactive placebo.

The volunteers were tested for their ability to recognise certain tastes before the drug was given and again two hours later.

The result was that the volunteers were able to detect different tastes (salt, sugar, sour, and bitter) at lower concentrations, thus enhancing their ability to taste.

Dr. Lucy Donaldson, senior author of the study says because they found that different tastes change in response to changes in the two different neurotransmitters, it is hoped that by using a taste test in depressed people it will show which neurotransmitter is affected in their illness.

Dr. Jan Melichar, the lead psychiatrist for the study says the results are very exciting as they mean it may now be possible to get patients on the right drugs immediately.

The findings were published in the Journal of Neuroscience.