Serotonin is a complicated neurotransmitter that, contrary to other neurotransmitters, has an influence on everything in the body. It’s currently believed to aid in anxiety, depression, impatience, impulsiveness, anger, etc. One of the main reasons for this is that the metabolite of serotonin, 5-HIAA, is low in people with these symptoms. The research is thus based on an assumption that brain serotonin is low, because 5-HIAA is low. However, low 5-HIAA is actually a sign that very little serotonin is being broken down and that there is actually an excess of serotonin in the brain.
There are mainly three ways that serotonin can become elevated in the brain, firstly through an increase in its synthesis via tryptophan hydroxylase 2 (TPH2), secondly by reduced monoamine oxidase A function (MAO-A breaks down serotonin) and thirdly, by a decrease in SERT (serotonin transporter) function.
Elevated TPH, and low MAO-A and SERT activity will lead to elevated serotonin. This article is not specific to discuss if serotonin is the good or bad guy and why, but here I describe the personality trait someone with high serotonin might have. Keep in mind that serotonin is rarely, if ever, elevated on its own, but most likely in conjunction with estrogen, cortisol, histamine, prostaglandins, nitric oxide, prolactin, glutamate, etc. So many of the personality trait of serotonin can be due to elevated glutamate or cortisol for example, because serotonin potentiates the release of those hormones. But to lower cortisol or glutamate directly will help a bit, but will not fix the condition, because serotonin is the root cause of it and if it’s not kept in rein, lowering cortisol or glutamate will not help much.
Here are some of the most common high serotonin personality traits:
- Tiredness/lethargy, easily tired and even chronic fatigue syndrome (due to elevated 5-HT2A receptor) (8, 8).
- Inhibiting TPH prevents this fatigue. However, serotonin isn’t the only neurotransmitter involved in fatigue, but also cortisol, acetylcholine, noradrenaline, the serotonin:dopamine ratio, kynurenine pathway, etc.
- Overexcitation – ADD, ADHD, get distracted easily, anxiety, impulsivity, restlessness, overthinking, rumination, etc. (due to elevated 5-HT2A receptor) (8).
- Rigid thinking and mental inflexibility (8). Some studies actually say that activation of the 5-HT2A receptor (via psychedelics such as LSD, shrooms, etc.) reduce rigid thinking, but this is actually because it stimulates glutamate release, which then stimulates dopamine release via the NMDA receptor and dopamine is involved in creativity and flexible thinking (8). Plus, after psychedelics exposure, people usually feel a kind of “bliss” for a week or two afterward, and this is due to 5-HT2A downregulation.
- Depressed, sadness, feeling down, reduced desire to do other things like go out and have fun, social anxiety and withdrawal, etc. (8, 8, 8)
- Reduced cognitive function (not necessarily lack of knowledge, but intuitive thinking) (8). However, they might think they are smart and have all the answers in a very authoritative way.
- Narcissistic (8) – delusions of grandeur, fantasize about power, exaggerated sense of self-importance, requiring constant admiration, etc.
- Reduced senses (sensory perception) – anhedonia, apathy, reduced smell, hearing, taste, sensation, euphoria to music, etc. (8, 8)
- Overly analytical, with a negative bias (8).
- Sinical, negative, doesn’t look at the bright side of life (8).
- Feel “icky” – often just want to be left alone.
- Non-assertive – rather rude and aggressive dominate, which might come over as assertiveness, but is totally the opposite (5-HT2C is inversely correlated with assertiveness) (8). As Philosopher Eric Hoffer said: “Rudeness is the weak man’s imitation of strength.” (8)
- OCD (5-HT2C activation increases compulsivity and lowers dopamine and noradrenaline) (8, 8, 8).
- Aversive, passive-aggressive, but can also be full-on aggressive and violent (8).
- Don’t care about the consequences of wrong decisions. This can also be due to low dopamine (place less weight upon the magnitude of bad outcomes) (8). Life feels like a joke or means nothing.
- Anticipation anxiety, enhanced anticipation of, and sensitivity to threat-related stimuli, punishment, and negative feedback (8).
- Emotionally unstable – very sensitive to emotional triggers (feels like you have to walk on eggs around the person), get easily triggered emotionally due to a traumatic experience with someone in the past, emotional and argumentive about their beliefs and views, etc. (8, 8)
- Bullying – this is usually due to trauma early on in life of being abused, either mentally or physically themselves and now they do it to others.
- Reduced verbal fluency, memory, attention, planning ability, and psychomotor performance (8, 8, 8, 8). However, estrogen and serotonin promote the desire to talk, thus people with high estrogen and serotonin talk a lot.
- Fearful – scared of losing, low confidence and assertiveness.
- Futile patience (keep on waiting to receive something, even if it’s improbable or irrational) and obedient (due to not wanting to rock the boat, scared, “zombified”, not questioning things, etc.) (8, 8).
- Suicidal – thoughts and even attempts (8, 8, 8).
- Delirious (8).
- Mood swings – bipolar mania (8, 8). Antagonism of 5-HT2A (which lowers excess glutamate) and the histamine receptor H1 and agonism of the 5-HT1A receptor (which lowers serotonin) helps.
- Easily agitated, argumentative, violent, aggressive, intermittent explosive disorder (8, 8).
- Psychopathic behavior (8).
- Non-likable – It is shown that males find high serotonin females less attractive and act more aggressive towards them (8). However, high serotonin people do attract others that are similar to them (who also have elevated serotonin).
People with high serotonin will obviously not always have the exact same personality traits; so you might know someone who has some or a lot of the traits but not all of them. This is because of a difference in receptor expressions, as well as other hormones, which levels vary between people.
But in general, people with high serotonin have low dopamine and are prone to being unstable, negative, make decision and cognitive errors, pessimistic (can also have a lot of fake confidence and be overly (fake) optimistic), leach on other people’s energy, have the answers to everything, are overly logical as opposed to creative, want people to feel sorry for them, depressed, irritating and truly annoying, passive-aggressive/up-in-your-face aggressive, enjoy picking on people to make themselves look or feel better, think highly of themselves (but deep inside are highly insecure and lash out if any insecurity is exposed), can’t take it to be wrong, etc, etc, etc.
To sum it up even shorter, there are mainly two serotonin personalities, one that is up-in-your-face aggressive, dominant (not calm and assertive), narcissistic, authoritative and controlling, and the other one is more of a weak, depressed, anxious, socially isolated (feel sorry for me), personality, or a combination of both (“two-faced”, split personality etc.).
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