Dopamine is a powerful player in our cognitive function – impacting mood, movement, and motivation. Genetic variants in the dopamine receptors influence addiction, ADHD, neurological diseases, depression, psychosis, and aggression.
Please keep in mind as you read this article that I’m not a neuroscientist — instead, I’m just consolidating the research and translating it into something that is (hopefully) easier to read and apply. If you are under psychiatric care, do talk with your doctor before making any changes to anything you are currently doing.
Let’s start with the basics here. Dopamine acts as a neurotransmitter in the brain, transmitting a signal from one neuron to the next. It is a monoamine neurotransmitter, and also a catecholamine. A monoamine just means that it contains a single amine group – and this is important in the way that it is regulated in the brain
Dopamine is derived from the amino acid tyrosine, which is converted to L-dopa and then to dopamine.
Dopamine is involved in:
It acts on the dopamine receptors to cause motion and emotion.
Dopamine is important in how the brain controls movement, and it needs to be balanced. Too much dopamine leads to more movement – such as tics and involuntary movement. Too little dopamine leads to less movement – such as in Parkinson’s.
Dopamine is also important in emotions. Excess dopamine leads to euphoria, hallucination, and psychosis. Dopamine causes conditioning – for example, learning either not to do something (via punishment) or learning to do something through reward. Not enough dopamine leads to anhedonia – that feeling of not caring about anything.
Dopamine also functions within the hypothalamus and pituitary gland to affect hormones. Specifically, dopamine inhibits prolactin. Without enough dopamine, it can lead to amenorrhea (lack of periods) in women and impotence and gynecomastia (moobs) in males.
There are two small regions deep in the brain where dopamine is made – the substantia nigra and the ventral tegmental area. From there, it travels via tracts to other areas of the brain.
Dopamine doesn’t do anything by itself – it needs to bind with a receptor to cause an action. There are five different dopamine receptors in humans. They are coded for by the DRD1 through DRD5 genes. The receptors are responsible for the slightly different effects of dopamine in the various brain regions.
The most common dopamine receptor in the brain is DRD1. It is found in several regions of the brain including the neostriatum, basolateral amygdala, cerebral cortex, hypothalamus, and thalamus.
The DRD1 receptor is linked to the effects of alcohol consumption. Blocking the DRD1 gene decreases the alcohol-seeking behavior in animal studies. It also decreases heroin and cocaine seeking-behavior. [ref]
Working memory – short term memory needed for thinking and speaking – depends on the DRD1 receptors in the prefrontal cortex. Interestingly, working memory as considered to have a strong genetic component based on the DRD1 gene variants. [ref]
The DRD2 receptor is less abundant in the cerebral cortex than the DRD1 receptors, but it is abundant in other areas of the brain with dopaminergic neurons.
Both agonists and antagonists of the DRD2 receptor have been shown in animal studies to decrease alcohol and opiate consumption. The studies show that higher levels of either an agonist (something that stimulates the receptor) or antagonist (something that blocks the receptor) alter the addictive response. [ref]
The DRD3 receptor is found in the ventral striatum and other limbic areas. In humans, there are low amounts of the DRD3 receptors found in the cortical regions. This differs from other species and is a good reminder that animal studies may not be totally applicable to humans. [ref]
The DRD3 receptor has a higher affinity for dopamine (>20-fold higher than DRD2 receptors). This means that dopamine is more likely to bind with the DRD3 receptors, and high levels of dopamine will prompt the brain to make more DRD3 receptors. This ability to change with fluctuating dopamine levels makes the DRD3 receptor critical in dopamine-related functions and cognition.[ref]
This dopamine receptor is found at lower levels than DRD1 through DRD3. It is found in the retina, cerebral cortex, amygdala, hypothalamus, and pituitary. The DRD4 receptor hasn’t been shown to be all that important in alcohol, opiate, or cocaine addiction. [ref]
The DRD5 receptor is very similar to the DRD1 receptor, and they are often located together. There seems to be a lot more research on DRD1, but often substances that bind to DRD1 also bind to DRD5. [ref]
Addiction to drugs causes a compulsive drug-seeking behavior. The dopamine system is involved in the rewarding effects of drugs, and a lot of addictive drugs increase dopamine levels in certain regions of the brain. It has been known since the 1990s that blocking dopamine transmission takes away the reward effects of some addictive substances, such as cocaine and amphetamines. [ref]
There are three theories on how dopamine is related to addiction. First, is that the extra dopamine produced by addictive substances trains the brain through the reward system. It is the idea that the brain learns to like the drug, or makes it a habit. The second theory is that addictive substances change the brain circuits, making them hypersensitive. Third, researchers theorize that there is an imbalance between dopamine and other neurotransmitters. [ref]
There are several diseases that are associated with altered dopamine.
Check your genetic data for rs4532 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs5326 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs686 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs6277 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs1801028* (23andMe v4; AncestryDNA):
*given in plus orientation to match 23andMe, AncestryDNA data
The following variant is known as the DRD2 TaqI A variant, located in the ANKK1 gene. It is thought to be linked with a polymorphism in the DRD2 gene that affects its function.[ref]
Check your genetic data for rs1800497 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs6280 Ser9Gly (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs1800955 (23andMe v4 only):
The COMT gene codes for the enzyme that breaks down dopamine and other catecholamine neurotransmitters. A common variant can decrease or increase the speed at which this enzyme works.
Check your genetic data for rs4680 (23andMe v.4 and v.5):
This gene codes for the dopamine transporter, known as DAT1. Below are just a couple of the variants in DAT1 — perhaps I’ll follow up with a longer article on this soon.
Check your genetic data for rs27072 (23andMe v.4 and v.5):
Again – let me caution that you don’t want to experiment with your neurotransmitters if you are under psychiatric care without talking with your doctor. Do more research, talk with your doctor/health care practitioner, and know what you are doing before you mess around here.
Diet – get enough protein to produce dopamine:
Dopamine is produced by converting the amino acid tyrosine into l-dopa and then dopamine. The body produces tyrosine from phenylalanine, which you get from your diet. You can also get tyrosine from foods. A diet that includes enough protein-rich foods (containing tyrosine/phenylalanine) is needed for dopamine production. [ref]
There have been several studies looking at the cognitive response in people who ate a diet lacking phenylalanine and tyrosine for a day. The results show that the acute decrease in dopamine changes response to timing, decreased functional connectivity in the brain, and slowed reaction time.[ref][ref][ref]
Natural dopamine receptor antagonists (blocks the receptor):
In general, atypical antipsychotic medications are antagonists of the DRD2 receptor. This makes sense when you think about too much dopamine causing hallucinations, euphoria, etc — things associated with a psychotic break.
Yohimbine is derived from the bark of an African tree, P. yohimbe, and traditionally used as an aphrodisiac (although human studies don’t really back that up). It is marketed as a supplement and used for weight loss. It acts on the adrenergic receptors, serotonin receptors, and is also an antagonist of the DRD2 and DRD3 receptors. [ref] Yohimbine is also used in animal studies to cause anxiety… so you may want to watch out for this as a side effect. [ref]
Ningdong granule is a traditional Chinese medicine preparation used for Tourette’s syndrome. It has been shown to regulate extracellular dopamine and also decrease binding to DRD2. [ref]
Natural ways to reduce dopamine:
An animal study showed that chronic lithium treatment – similar to prescription levels of lithium rather than supplemental lithium orotate – were able to blunt an anticipated spike in dopamine. This was thought to be one way that lithium may be effective in mania, which should be a high dopamine state.[ref] Other studies, though, show that lithium increases dopamine following a TBI.[ref]
At least in rats, a ketogenic diet reduced the effects of daily cocaine injections.[ref] This is obviously not a study that is going to be repeated in humans…
In kids with epilepsy, when they went on a ketogenic diet to control the seizures, their dopamine metabolites decreased. [ref]
Natural dopamine receptor agonists:
L-theanine has been shown in animal studies to activate the DRD1/DRD5 receptors. Theanine is a component of green tea and is also sold as a supplement.
Natural dopamine boosters:
Sugar causes the release of dopamine. Research shows this is both from the taste of sugar and from the nutrition (energy) from sugar.[ref] You know how you read headlines stating that sugar is just like cocaine in the brain — well it turns out that isn’t really correct. Sugar affects dopamine in different areas of the brain (natural reward areas) than cocaine does. [ref]
Gingko biloba increases dopamine levels (in rat brains). The effect was seen after chronic (14-day) administration of the gingko. [ref][ref] Perhaps this is why Ginkgo Biloba is thought to increase memory… You can get gingko at your local health food stores or on Amazon.
Bacopa is an herbal supplement that is marketed as helping with brain function. In rats, bacopa decreased serotonin and increased dopamine. It has also been shown in studies to potentially help with dementia and Parkinsons. [ref] You can get bacopa at health food stores or on Amazon.
Mucuna pruriens, aka velvet beans, have traditionally been cultivated as a vegetable in Asia, Africa, and the Pacific Islands. Mucuna prurien extract is high in l-dopa, the precursor to dopamine, and it has been used as a natural treatment for Parkinson’s. [ref] You can get a concentrated extract as a supplement — or perhaps you can find velvet beans at an ethnic grocery store in your area?
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