The researchers gave healthy volunteers antidepressant drugs that increase levels of the neurotransmitters serotonin and noradrenaline. The drugs enhanced their ability to taste. The volunteers were being able to detect different tastes (salt, sugar, sour, and bitter) at lower concentrations.
Dr Lucy Donaldson, senior author on the paper, said: “When we increased serotonin levels we found that people could recognise sweet and bitter taste at much lower concentrations than when their serotonin levels were normal. With increased noradrenaline levels the same people could recognise bitter and sour tastes at lower concentrations. Salt taste doesn’t seem to be affected at all by altering either of these neurotransmitters.” She added: “Because we have found that different tastes change in response to changes in the two different neurotransmitters, we hope that using a taste test in depressed people will tell us which neurotransmitter is affected in their illness.”
Dr Jan Melichar, the lead psychiatrist on the paper, added: “This is very exciting. Until now we have had no easy way of deciding which is the best medication for depression. As a result, we get it right about 60-80% of the time. It then takes up to four weeks to see if the drug is working, or if we need to change it. However, with a taste test, we may be able to get it right first time.”
These results give an important insight into how neurotransmitters affect the taste system. It seems that tasting bitter things can be changed by changes in both serotonin and noradrenaline levels, that sweet taste is affected by only serotonin levels, and that sour taste is affected by noradrenaline. These findings may also explain why anxious and depressed individuals have diminished appetite. The results also show that taste is related to anxiety levels, even in generally well people.
MEDICA.de; Source: University of Bristol