What is serotonin and what does it do?

Does serotonin really relieve depression?

SSRIs have been used since the 1980s to treat depression by boosting serotonin levels.

Medication such as SSRIs are believed to relieve the symptoms of depression by boosting serotonin levels in the body, but exactly how this works is unclear.

Some scientists have suggested that, while SSRIs seem to work for some people, increasing serotonin levels is unlikely to directly improve symptoms of depression.

One problem is that it is possible to measure serotonin levels in the bloodstream, but not in the brain. Researchers do not know whether serotonin levels in the bloodstream reflect the serotonin levels in the brain, or if SSRIs can really affect the brain.

In 2014, a mouse study suggested that serotonin may not play a role in depression. Researchers created some mice that were not able to produce serotonin in their brains. The mice showed no signs of depression, even when placed under stress.

In 2015, however, other scientists found that mice that lacked serotonin were more susceptible to social stressors than healthy control mice.

While SSRIs appear to help some people with depression, some scientists now argue that "simple biochemical theories that link low levels of serotonin with depressed mood are no longer tenable."

One editorial published in the BMJ in 2015 refers to the use of SSRIs to treat depression as "the marketing of a myth."

SSRIs are also used to treat symptoms of anxiety, panic disorder, and obsessive-compulsive disorders.

Adverse effects of SSRIs

SSRIs have some side effects, but these usually decrease after 2 to 4 weeks of use.

• nausea
• diarrhea
• weight loss or gain
• increased sweating
• dizziness
• sleepiness or insomnia
• tremor
• dry mouth
• headache
• restlessness
• suicidal thoughts
• sexual dysfunction

SSRIs and suicide

SSRIs do not begin to work on depression for a couple of weeks. During the first month of treatment it is possible for symptoms of depression to worsen before positive changes are noticed. Report any suicidal thoughts immediately.

There are reports of some younger users of Zoloft experiencing suicidal ideation.

The FDA requires all antidepressants to carry a black-box warning about the danger of suicide during the initial stages of treatment, especially in children.

Other uses of SSRIs

SSRIs have been used for conditions other than depression.

 

 

 

Treatment with serotonin may help relieve migraine

Antiemetics: The antiserotonergic drugs that act on the serotonin receptors, such as ondansetron (Zofran), are important for treating nausea caused by chemical toxins, including drugs used in chemotherapy and general anesthesia. They act centrally on the part of the brain involved with nausea.

Migraine: Serotonergic vasoconstrictive antimigraine drugs, or triptans, such as almotriptan (Axert), can reduce migraine symptoms and are well tolerated.

Appetite suppressants: Serotonergic appetite suppressants, such as fenfluramine (Pondimin) and chlorphentermine, have been used for reducing appetite, but they are no longer licensed for this purpose.

Parkinson's disease: The serotonergic system has been linked to cognition, emotion, and motor behavior. Changes in this system may therefore have an effect on the motor and non-motor features commonly associated with Parkinson's disease. Serotonergic drugs have been used to treat Parkinson's disease. They are no longer licensed, but research continues in this area.

Premenstrual syndrome (PMS): The cause of this condition is unknown, but an oversensitivity to one of the female hormones, progesterone, seems to reduce the level of serotonin in the brain. Serotonin inhibitors are sometimes used to relieve symptoms around the time when they occur.

Other possible uses of SSRI-type drugs include the treatment of obesity and irritable bowel syndrome (IBS).

Serotonin syndrome

Serotonin syndrome, or serotonin toxicity, can happen if a person takes two serotonin-boosting drugs at the same time.

There is excessive stimulation of the CNS and peripheral serotonin receptors. It is usually the result of a drug interaction, but at least one medical condition can trigger it.

Drug interactions: The use of prescribed medications, illegal drugs, or dietary supplements can lead to serotonin syndrome, for example, if a person is susceptible or if two drugs that affect serotonin levels are taken at the same time. Symptoms can appear 6 to 8 hours after taking the drug.

The FDA have warned, for sample, against taking SSRIs with triptans, a medication to treat migraine, because of the risk of serotinin syndrome.

Drugs that target serotonin levels cannot be given with MAOI's. MAOIs are another approach to treating depression and work on different neurotransmitters and their receptors.

Recreational drugs: The use of recreational drugs, such as ecstasy and MDMA, leads to a high and sudden release of serotonin. If used with prescribed serotonergic drugs, this can increase the risk of serotonin syndrome.

Carcinoid tumors: These cancerous tumors, commonly found in the GI tract, can cause too much serotonin to be released. Most carcinoid tumors have no symptoms. They are often found during tests or procedures for other conditions.

Serotonin syndrome leads to excessive nerve activity.

Signs and symptoms include:

• agitation and restlessness
• confusion
• increased heart rate and blood pressure
• pupil dilation
• diarrhea
• headaches
• shivering
• sweating
• loss of muscle co-ordination
• goosebumps
• muscle rigidity

Severe serotonin syndrome is life-threatening in 2 to 12 percent of cases.

Symptoms include a high fever, irregular heartbeat, seizures and unconsciousness.

The use of a single drug does not usually result in serotonin toxicity.

Treatment

Treatment focuses on managing symptoms and attempting to restore normal serotonin levels.

Discontinuing the medication may be enough to stop the symptoms.

Severe serotonin syndrome may need hospital treatment. Medications can be given to relax or paralyze the muscles, control heart rate and blood pressure, and, in some cases, to block the production of serotonin.

Oxygen and intravenous fluids may be given to maintain normal levels of oxygen in the bloodstream and to treat fever and dehydration.

Boosting serotonin levels

As well as SSRIs and illegal drugs, there may be other ways of increasing serotonin levels in the body.

Mood induction: Alterations in thought, either through psychotherapy or self-induction, could increase levels of serotonin if the interaction between serotonin synthesis and mood is a two-way relationship.

Light: Already used as a treatment for seasonal affective disorder (SAD), a few studies have suggested that it can be used to treat depression as well.

Exercise: Exercise has an antidepressant effect, and some research has suggested that it can increase brain serotonin function.

Diet: Foods that have higher levels of tryptophans could be linked to improved mood and cognition, possibly due to increased serotonin levels. Also serotonin is available as a supplement, which can be purchased online.

These are all areas that require further study, as current knowledge remains speculative.

Foods

Tryptophans are an amino acid that can be found in food. Some research has linked a higher intake of dietary tryptophan with more positive mood scores, possibly because tryptophan boosts serotonin levels.

 

 

 

Bananas are said to contain serotonin, but can this boost happiness in whose who eat them?

High-protein foods: Some foods, such as turkey, eggs, and cheese, are believed to contain tryptophan and to increase tryptophan levels in the blood.

Bananas: These contain serotonin, and they have been recommended for lifting mood. But they can only improve a person's mood if the serotonin they contain will reach the brain.

Tryptophan is a precursor, a main ingredient that the body needs to make serotonin. Eating foods high in this essential chemical doesn't mean that the body will absorb and use it. But making tryptophan available when needed will improve serotonin synthesis.

In some studies, however, older people who were given tryptophan supplements performed better on cognitive tests than they had before.

There is a growing interest in the idea that gut microbiota might influence the CNS and cognition through a link known as the gut-brain access. In this case, serotonin in the digestive system may be able to influence mood.

The following foods are said to contain tryptophans:

• cheese
• turkey
• eggs
• soya products
• salmon
• talbina, a dish made from barley

However, while foods may contain tryptophan, it may be in too small an amount to make a difference. Most studies have used supplemental forms of tryptophan.

A protein known as α-lactalbumin, for example, is found in milk. It contains more tryptophan than most proteins. However, scientists suggest that it is probably not practical to consume the amount that would be needed to make a difference.

In the 1980s, corn that was bred with a higher tryptophan content was successful in preventing pellagra. Population studies suggest that people for whom this corn was a major part of the diet showed fewer aggressive tendencies, although this could have been for other reasons. It is possible that the tryptophans in the corn increased people's serotonin levels.

Studies in which people consumed tryptophan-enriched drinks and other nutrient-based treatments have produced mixed results.

Until now, there is little evidence that a specific diet can affect mood or depressive symptoms.

However, following a healthful and varied diet has been found to produce a range of health benefits and to boost overall wellbeing.

The 2015-2020 Dietary Guidelines for Americans urge people to focus on a varied diet and to aim to obtain nutrients from food sources as far as possible.

Tryptophan supplements are available online, but they should not be used without first speaking to a doctor, because of the risk of serotonin syndrome.

Much remains unknown about serotonin. The difficulties surrounding the study of brain functions means that it will be some time before a full knowledge of serotonin can be acquired.

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