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.
This article covers information on neurotransmitters related to psychiatric health. If you are under psychiatric care, talk with your doctor before making any changes.
Members will see their genotype report below, plus additional solutions in the Lifehacks section. Consider joining today.
Dopamine: Neurotransmitter for motion and emotion
Dopamine acts as a neurotransmitter in the brain, transmitting a signal from one neuron to the next. It is a monoamine neurotransmitter, classified as 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:
- Movement
- Reward
- Memory
- Lactation
- Attention
- Sleep regulation
The dopamine molecule acts on dopamine receptors to cause motion and emotion.
Motion:
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.
Emotion:
Dopamine is also important in emotions. Excess dopamine leads to euphoria, hallucinations, 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.
Prolactin:
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.
Where is dopamine made?
There are two small regions deep in the brain where dopamine is made:
- the substantia nigra
- the ventral tegmental area
From there, it travels via tracts to other areas of the brain.
Dopamine Receptors: Understanding the different effects of dopamine
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 various brain regions.
DRD1 receptor:
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 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 is considered to have a strong genetic component based on the DRD1 gene variants.[ref]
DRD2 receptor:
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]
DRD3 receptor:
The DRD3 receptor is found in the ventral striatum and other limbic areas. In humans, there are low amounts of 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. The ability to change with fluctuating dopamine levels makes the DRD3 receptor critical in dopamine-related functions and cognition.[ref]
DRD4 receptor:
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]
DRD5 receptor:
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]
Dopamine and Addiction:
Addiction to drugs causes 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. In fact, 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, 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’s circuits, making them hypersensitive. Third, researchers theorize that there is an imbalance between dopamine and other neurotransmitters. [ref]
Mental disorders associated with abnormal dopamine levels:
Several diseases are associated with altered dopamine.
- Tics / Tourettes – excess striatal dopamine due to GABAergic network dysfunction[ref]
- Psychosis – excess dopamine
- Schizophrenia – excess dopamine in some areas of the brain (causes hallucinations) and not enough in others[ref][ref]
- Addiction – caused in part by repeated surges in dopamine (reward) and increased dopamine receptors
- ADHD -associated with low dopamine function in certain areas of the brain[ref]
- Bipolar affective disorder – high dopamine during mania which elevated DRD2 and DRD3 receptors, coupled with reduced dopamine during depression[ref]
- Anorexia – decreased reward (dopamine) for food along with other neurotransmitter imbalances (such as histamine)[ref]
- Depression – low dopamine is seen in people with inflammation-associated depression.[ref]
Additionally, Parkinson’s disease is caused by not enough dopamine due to degradation of the dopamine-producing area of the brain (substantia nigra).
Related article: ADHD Genes
Connections between dopamine levels and inflammation:
Neuroinflammation in dopaminergic neurons causes cell death and a reduction in dopamine. This is thought to be the cause of Parkinson’s disease.[ref]
Tetrahydrobiopterin (BH4) is needed for the synthesis of dopamine. Pro-inflammatory cytokines reduce the production of BH4, thus potentially reducing dopamine levels in situations of systemic inflammation.[ref]
” Dopaminergic neurotransmission is very sensitive to inflammation. At the periphery, the production of neopterin and nitric oxide during inflammation consumes tetrahydrobiopterin to the detriment of the hydroxylase enzymes that use this compound as a cofactor”.[ref]
Dopamine Receptor Genotype Report:
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DRD1 gene: dopamine receptor 1
Check your genetic data for rs4532 (23andMe v4, v5; AncestryDNA):
- C/C: increased risk of treatment-resistant schizophrenia[ref]; better response accuracy in complex tasks[ref];
- C/T: somewhat increased risk of treatment-resistant schizophrenia[ref]
- T/T: typical
Members: Your genotype for rs4532 is —.
Check your genetic data for rs5326 (23andMe v4, v5; AncestryDNA):
- T/T: decreased DRD1 in certain brain areas; increased risk of heroin addiction[ref]; poorer cognition and worse strategic planning[ref]
- C/T: increased risk of schizophrenia[ref], poorer cognition and worse strategic planning[ref]
- C/C: typical
Members: Your genotype for rs5326 is —.
Check your genetic data for rs686 (23andMe v4, v5; AncestryDNA):
- A/A: typical; more DRD1 expression
- A/G: intermediate DRD1 expression
- G/G: less DRD1 expression[ref]; decreased risk of rapid opioid dependence[ref]
Members: Your genotype for rs686 is —.
DRD2 gene: encodes dopamine receptor 2
Check your genetic data for rs6277 (23andMe v4, v5; AncestryDNA):
- A/A: increased D2 receptor binding potential; increased susceptibility to stuttering[ref]; decreased risk of schizophrenia in Caucasians[ref]; better avoidance learning from negative outcomes[ref]; better rule-based learning[ref]
- A/G: common genotype in Caucasians
- G/G: typical worldwide; poorer performance on working memory test[ref]; decreased cognitive ability in older adults (compared to AA)[ref]
Members: Your genotype for rs6277 is —.
Check your genetic data for rs1801028* (23andMe v4; AncestryDNA):
- G/G: typical (Ser)
- C/G: may not respond as well to risperidone; increased risk of schizophrenia[ref]
- C/C: (Cys) may not respond as well to risperidone; increased risk of schizophrenia[ref]
*given in plus orientation to match 23andMe, AncestryDNA data
Members: Your genotype for rs1801028 is —.
The following variant is known as the DRD2 TaqI A polymorphism, 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):
- A/A: (DRD2*A1/A1) reduced number of dopamine binding sites[ref] increased risk of opioid dependence[ref]; increased BMI (susceptibility to food reward)[ref]; higher consumption of fried food[ref]; poorer working memory[ref]; increased suicide risk[ref]; increased risk of PTSD[ref] increased ADHD in males[ref]
- A/G: (DRD2*A1/A2) increased risk of opioid dependence; reduced number of dopamine binding sites; increased BMI (susceptibility to food reward)[ref]; higher consumption of fried food[ref] poorer working memory[ref]; increased risk of PTSD;
- G/G: (DRD2*A2/A2) typical; aerobic exercise increases motor learning[ref]
Members: Your genotype for rs1800497 is —.
DRD3 gene: encodes dopamine receptor 3
Check your genetic data for rs6280 Ser9Gly (23andMe v4, v5; AncestryDNA):
- C/C: poorer executive function (psychosis patients)[ref], much better response to risperidone (antipsychotic used in autism)[ref]; increased risk of alcohol dependence[ref], decreased risk of bipolar disorder[ref]
- C/T: better response to risperidone (antipsychotic)
- T/T: typical
Members: Your genotype for rs6280 is —.
DRD4 gene: encodes dopamine receptor 4
Check your genetic data for rs1800955 (23andMe v4 only):
- C/C: more likely to be a novelty seeker, more impulsive[ref]; more likely to smoke[ref]; more likely to take risks in ski/snowboarding[ref]; possibly less likely to become addicted to heroin[ref]
- C/T: somewhat more likely to be a novelty seeker; more likely to smoke
- T/T: typical
Members: Your genotype for rs1800955 is —.
COMT gene: encodes the enzyme that breaks down dopamine and other catecholamine neurotransmitters. A common SNP can decrease or increase the speed at which this enzyme works.
- The G allele (Val) has higher COMT enzymatic activity, causing a more rapid breakdown of the neurotransmitters and thus lower levels of dopamine. In most populations, the G allele is the most common.[ref]
- The A allele (Met) has lower COMT enzyme activity and, thus higher levels of dopamine. This SNP in the COMT enzyme is said to have lower activity because it breaks down faster at normal body temperature.[ref]
Check your genetic data for rs4680 (23andMe v4, v5):
- G/G: higher COMT activity, lower dopamine & norepinephrine, higher pain tolerance (Val)
- A/G: intermediate COMT activity
- A/A: 40% lower COMT activity, higher dopamine & norepinephrine, lower pain tolerance (Met)
Members: Your genotype for rs4680 is —.
SLC6A3 gene:
This gene codes for the dopamine transporter, known as DAT1.
Lifehacks:
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. Read the research and talk with your doctor or health care practitioner.
Diet hacks: get enough protein to produce dopamine for your brain to function right
Dopamine is produced by converting the amino acid tyrosine first into l-dopa and then into 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]
The rest of this article includes supplement research and a visual overview of your genetic data. It is for Genetic Lifehacks members only. Consider joining today to see the rest of this article. An active subscription is required to access this content. Join Here for full access to this article, genotype reports, and much more! Already a member? Log in below.
Member Content:
Related Genes and Topics:
Serotonin Genes
Serotonin is a neurotransmitter that is important in depression, sleep, and many other aspects of health. Learn how genetic variants in the serotonin receptor genes impact their function.
COMT Gene
Wondering why your neurotransmitters are out of balance? It could be due to your COMT genetic variants. The COMT gene codes for the enzyme catechol-O-methyltransferase which breaks down (metabolizes) the neurotransmitters dopamine, epinephrine, and norepinephrine.
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