Serotonin and Foul Mood

By Dov Michaeli

You know who I am talking about; yes it’s you! Here we are driving across the beautiful countryside, admiring the tall Ponderosa pines, the Big Sky country, big smiles across our faces. Then you fall quiet. Are you lost in thought? Are you contemplating the meaning of life? “Anything wrong”? I ask. “I am hungry!!!” you blurt out, not so much an answer as a cri de coer.

Some people can go without food for hours on end, others can’t tolerate even the slightest delay in putting something in the stomach. What’s going on? It certainly is not hypoglycemia per se; the symptoms are different. Could it be a manifestation of IED? No, I am not talking of the terrorist variety. There is a psychiatric disorder called Intermittent Explosive Disorder, but its symptoms of intense, extreme and uncontrollable outbursts of violence which may be triggered by cues of provocation such as a facial expression of anger, are a lot more, well, explosive than the phenomenon we are dealing with here.

Finally, the Answer…

In a paper in the journal Biological Psychiatry a Cambridge University team looked into this vexing problem. Brain serotonin, a neurotransmitter known to affect mood, had been shown to fluctuate in response to hunger and stress. For this study, serotonin levels in 19 healthy volunteers were altered by manipulating their diet. On the serotonin depletion day, the volunteers were given a mixture of amino acids that lacked tryptophan, the building block for serotonin. On the placebo day, they were given the same mixture but with a normal amount of tryptophan. They then scanned the volunteers’ brains using functional magnetic resonance imaging (fMRI) as they viewed faces with angry, sad and neutral expressions. Using the fMRI, they were able to measure how different brain regions reacted and communicated with one another when the volunteers viewed angry faces, as opposed to sad or neutral faces.

There are specific brain regions that are involved in processing emotion, including the amygdala, and areas in the frontal lobes that are in charge of regulating and modulating the inputs from those areas (prefrontal cortex and anterior cingulated lobe). The research revealed that when levels of serotonin in the brain are low, communications between these two areas are weaker than those present under normal levels of serotonin. And this finding suggests that low levels of serotonin may make it more difficult to control emotional responses to anger.

Using a personality What’s to be done? questionnaire, the researchers also determined which individuals have a natural tendency to behave aggressively. In these individuals, the communications between the amygdala and the frontal lobes were even weaker when serotonin was depleted. As a result, those individuals who might be predisposed to aggression were the most sensitive to changes in serotonin depletion.


First, what not to do: don’t argue, don’t psychoanalyze, and don’t get upset. Also, don’t take some candy for a quick sugar high –this is not the right answer. When you fall into a sullen mood or feel some free-floating anger, get a turkey sandwich, or anything else that contains a large amount of protein. Tryptophan will put you in a better mood, and may even save your relationship.

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