The smell of freshly baked bread lingering in the kitchen adds to the delight from the first bite. The delight does not only come from our tastebuds, but mainly from a pleasure and reward function in the brain, which helps us to feel happy and even euphoric at times when experiencing or even anticipating the smell and taste of food, or any other activity that we like. All thanks to a “feel-good” chemical substance released in the brain, called dopamine.
Unfortunately, there is also a more sinister side to dopamine, as recreational drugs such as cocaine and heroin, also nicotine, cause huge boosts in dopamine production in the brain and the intense pleasurable feelings can prompt people to want to experience it again and again, leading to addiction.
What is dopamine?
Dopamine is a chemical which acts as a messenger between brain cells (neurons) and between the brain and the rest of the body. There are also other chemicals that act as messengers in the brain and these chemicals are referred to as neurotransmitters. Each neurotransmitter is a specific chemical that is released at the end of a neuron to carry a message, specific to that particular neurotransmitter, to a neighbouring neuron. The neurotransmitter travels across a tiny space between neurons, called the synapse, and then binds to receptors on the neighbouring cell to transmit a message.
Although neurotransmitters are released by neurons and can bind to other neurons, they can also bind to other types of cells, such as cells making up muscles or glands.
(This image shows a neurotransmitter crossing the synapse between two brain cells. The orange stars are molecules of dopamine travelling from one cell and binding to the receptors, indicated in blue, on the neighbouring cell)
Dopamine is mostly released when the brain expects a reward, but the specific messages that dopamine transmits not only plays a role in feelings of pleasure and reward, but it also plays a role in how we move, what we eat, how we learn and even in how we get addicted.
Where does dopamine come from?
Various neurotransmitters are made in different parts of the brain and the axons of these neurons project to different areas of the brain. Dopamine is mainly made in two thin and tiny areas in the midbrain, which together are smaller in size than a postage stamp. One area is called the substantia nigra and dopamine from this area helps to initiate movements and speech. Dysfunction or death of these dopamine producing brain cells results in the typical symptoms of Parkinson’s disease, which is a disease of the brain and nervous system that causes tremors and affects movement, mood, and memory.
The other area is close by and called the ventral tegmental area, which sends dopamine into the brain when we expect or receive a reward, telling the brain whatever we have just experienced is worth getting more of the same, be it food, sex, or drugs! Dopamine from this area plays a role in our thinking, emotions, and motivation, as well as in addiction.
In addition, dopamine is produced in the hypothalamus area of the brain where it acts as a neurohormone, as it is one of several hormones released by the pituitary gland, situated directly below the hypothalamus in the brain.
Dopamine also acts as a hormone, made by the adrenal glands situated on top of the kidneys, where it plays a minor role in the body’s fight-or-flight response in stressful situations.
Dopamine is produced in a two-step process. The amino acid tyrosine, derived from food, is first converted into another amino acid, L-dopa, which then undergoes another change (step two) as enzymes turn it into dopamine. Since dopamine is made from the amino acid tyrosine, food rich in tyrosine could potentially boost dopamine levels in the brain and may also improve memory and mental performance. Food high in tyrosine include chicken and other poultry, avocadoes, bananas, soy, pumpkin seeds, sesame seeds, as well as dairy products such as milk, yogurt, and cheese. There is some evidence which indicates that meditation may result in more dopamine being released in the brain.
Functions of dopamine:
Dopamine plays a major role in how we experience pleasure. Dopamine is best known as the “feel good” neurotransmitter due to its involvement in making us feel pleasure as part of the brain’s reward system. From an evolutionary viewpoint, says the Cleveland Clinic, this system was designed to reward ancient man when doing survival activities, such as eating, drinking, competing to survive, and reproducing. Our brains are hard-wired to seek out activities that release dopamine in the brain’s reward system.
The release of dopamine is also involved in reinforcement, as you feel good when doing something pleasurable, which makes you want more of that feeling. For example, once we have experienced the pleasure from sampling the freshly baked bread, we may come back for another slice or two. That is why junk food and sugar are so addictive, as they trigger the release of large amounts of dopamine in the brain. It makes you feel good, and you want to repeat the experience.
Dopamine also plays a role in many other neurological and physiological body functions, such as:
- Punishment and reward.
- Learning.
- Attention and focus.
- Memory.
- Attention.
- Motivation.
- Mood and emotions.
- Voluntary movement.
- Heart rate.
- Kidney function.
- Blood vessel function.
- Sleep and arousal.
- Dreaming.
- Pain processing.
- Stress response.
- Lactation.
- Causing blood vessels to relax or constrict.
- Increasing the removal of sodium (salt) and urine from the body.
- Reducing the production of insulin in the pancreas.
- Slowing the movement of the contents in the gastrointestinal tract (the gut) and protecting the lining of the gut.
- Reducing the activity of lymphocytes (a subtype of white blood cells) in the immune system.
Dopamine is not acting alone in these body conditions, but works with other neurotransmitters and hormones, for example with serotonin and adrenalin. Dopamine is but one of the neurotransmitters at work in the brain.
Effects of dopamine dysfunction:
The right amount of dopamine in the brain is associated with being in a good mood and contributes to learning, planning, motivation, and productivity, while also contributing to feelings of happiness and alertness.
Dysfunction of the dopamine pathways in the brain, due to changes in altered dopamine function – releasing too much or too little – and changes in dopamine receptors and signaling pathways, has been implicated in several disorders. While many diseases are associated with high or low levels of dopamine, not everything is known about the effects of dopamine on these conditions. For instance, does the high or low levels of dopamine cause the disease or does the disease cause the change in dopamine levels in the brain? In addition, the effect and function of a single neurotransmitter, dopamine in this case, can’t be viewed in isolation of other neurotransmitters or other chemicals in the body, as many interact with each other, says the Cleveland Clinic. There are, however, diseases in which the dopamine levels are high or low.
Diseases associated with high levels of dopamine:
Mania – Mental health disorders are often linked to too much or too little dopamine in different parts of the brain.
Obesity – Some people may have problems with their natural reward systems, which may affect the amount of food they eat before reaching satiety, which may be due to the body not releasing enough dopamine and serotonin, another feel-good hormone.
Addiction – (Discussed under the next heading.)
Diseases associated with low levels of dopamine:
Attention deficit hyperactive disorder (ADHD) – While the exact cause of ADHD is not clear, some research indicates that it may be due to a shortage of dopamine.
Parkinson’s disease – The loss of dopamine plays a part in the movement symptoms observed in people with Parkinson’s disease, such as tremors, stiffness, slowness of spontaneous movement, poor coordination, and poor balance. Dysfunction of dopamine pathways are implicated in the development of Parkinson’s disease. Dysfunction of dopamine pathways are implicated in the development of Parkinson’s disease. One type of neuron typically degenerates over time and as it does not have signals to send anymore, the body makes less dopamine.
Restless leg syndrome – The basal ganglia area in the brain uses dopamine as neurotransmitter to help the brain regulate and coordinate movement. If nerve cells in this area become damaged, the amount of dopamine is reduced, which may cause muscle spasms and involuntary movement. As dopamine levels naturally drop towards the end of the day, the symptoms of restless legs syndrome are often worse in the evening and at night.
Depression – Although depression is strongly linked to serotonin levels in the brain, low levels of dopamine can contribute to symptoms such as sadness, cognitive changes, and sleep problems.
Diseases associated with both high and low levels of dopamine:
Schizophrenia – Schizophrenia is associated with altered immune function and changes in dopamine receptors and signaling pathways in the brain. While some symptoms such as delusions and hallucinations may be caused by high levels of dopamine in certain areas of the brain, symptoms such as lack of motivation may be caused by low levels of dopamine.
Dopamine, drugs, and addiction:
Drugs, sex, and rock-n-roll…. Those were the days, my friend. We thought they’d never end – in addiction!
The “high” people experience when they use drugs comes from the huge boost in dopamine caused by drugs such as cocaine and heroin, also from nicotine. This is such a powerful rush that the person is left wanting more, and soon!
The dopamine spike prompts people to use those drugs again and again. The “reward” experienced in the brain that is associated with the “high” can lead to drug abuse and eventually to addiction. Addiction means the person is unable to control the use of a habit-forming drug and feel a compelling need to use the drug despite knowing the risks involved, whether it is cocaine, heroin, other so-called recreational drugs, alcohol, marijuana, or the nicotine in tobacco.
According to the Cleveland Clinic, these drugs interfere with the way nerve cells in the brain send and receive messages. While drugs such as marijuana and cocaine mimic natural neurotransmitters, other drugs such as cocaine and amphetamine either cause the release of large amounts of neurotransmitters or prevent the recycling of these neurotransmitters. (Amphetamines are psychostimulant drugs that speed up the messages travelling between the brain and the body. Some of the street names for these drugs are speed, uppers, and meths)
The big, fast increase in dopamine caused by these drugs overstimulate the “reward center” in the brain and with repeated use over time, the “reward center” becomes less sensitive and the person doesn’t derive the same feeling of pleasure from anything else but the drug. This increases the threshold for this kind of pleasure, resulting in having to take larger amounts of drugs to experience the same effect, while another area in the brain becomes more sensitive to the feelings of withdrawal, such as anxiety and irritability, as the effect of the drug wears off. This results in taking more drugs to get relief from the discomfort of withdrawal symptoms. In this way, addiction becomes a vicious cycle which develops from multiple mechanisms, says the Cleveland Clinic.
Drugs make the brain les able to produce dopamine naturally, leading to emotional lows when the person is sober. As the drug habit forms, the brain responds by toning down the release of dopamine, which results in needing more of the substance. The overactivation from drug abuse may affect dopamine receptors in such a way that the person starts to lose interest in other activities and acts more compulsively. Even if the person has stopped using the drug, exposure to the drug may trigger the desire for it, at the risk of relapsing.
Addiction not only results from the effects of dopamine in the brain, as other factors, such as genetics and environmental factors, can also play a role.
Conclusions:
Dopamine is a neurotransmitter and hormone that plays a role in many important body functions, such as movement, memory, happiness, and pleasurable reward. It is best known for its effect on mood and pleasure.
You don’t have to resort to drugs to increase dopamine levels, as there are many natural ways to improve dopamine levels. Food rich in magnesium and the amino acid tyrosine are the building blocks for dopamine production. Another way is to engage in activities that make you feel relaxed or happy, such as exercise, meditation, being in nature or even reading a book.
While it is well known that dopamine serves many vital neurological and cognitive functions, there is still much to learn about the complicated way in which dopamine interacts with other neurotransmitters and hormones. More research is needed, as some of these interactions are not entirely understood.
References:
Dopamine: The pathway to pleasure. Published 20 July 2021. Harvard Health Publishing. Harvard Medical School. (www.health.harvard.edu)
Feel-good hormones: How they affect your mind, mood, and body. Published 20 July 2021. Harvard Health Publishing. Harvard Medical School. (www.health.harvard.edu)
Dopamine. Reviewed 23 March 2022. Cleveland Clinic. (www.clevelandclinic.org)
What is dopamine? Reviewed 14 June 2021. WebMD. (www.webmd.com)
How does dopamine affect the body? Reviewed 5 November 2019. Healthline. (www.healthline.com)
The role of dopamine and its dysfunction as a consequence of oxidative stress. Published 6 December 2015. PubMed Central. National Centre for Biotechnology Information. US National Library for Medicine. National Institutes of Health. USA. (www.ncbi.nlm.nih.gov)
Explainer: What is dopamine? Published 17 January 2017. Science News for Students. (www.sciencenewsforstudents.org)
HEALTH INSIGHT