Without dopamine, we wouldn’t be able to feel driven and motivated. Dopamine increases attention, improves cognitive function, and stimulates our creativity. It makes us more social and extroverted and helps us form romantic and parental bonds. Read on to learn more about the function dopamine and whether “dopamine deficiency” can lead to health problems.
What Does Dopamine Do?
Health Effects:
Please note: diverse roles of dopamine as a neurotransmitter and hormone don’t necessarily imply any potential benefits of exogenous (outside) sources of dopamine in treatment or supplementation.
1) Responsible for Motivation
Dopamine is also known as the “motivation molecule.” It is responsible for intrinsic motivation and provides the motivational/internal drive to do things [1, 2, 3].
We do things because we find them rewarding. Dopamine is responsible for reward-seeking behavior [2, 4]. It is the main reward signal in the brain.
Activation of dopamine neurons results in a good/rewarding feeling, while inactivation causes aversion [5, 6].
In animal experiments, high, moderate and low concentrations of dopamine induce euphoric, seeking and aversive states, respectively [5].
Dopaminergic activity increases exploration [7]. And curiosity and interest are important components of intrinsic motivation [1].
Across different mammalian species, there is a linkage between dopamine and the positive experiences associated with exploration, new learning and interest in one’s environment [1].
People who often experience intrinsically motivated flow states in their daily activities have greater dopamine D2-receptor levels in specific brain regions [1].
On the other hand, low levels of dopamine make people and animals less likely to work for things. Dopamine blockade severely impairs effortful actions to obtain rewards [2].
Mutant mice that do not synthesize dopamine die of starvation owing to a lack of motivation to eat. Restoring neurotransmission in the striatum rescues these animals, whereas restoring it in the nucleus accumbens does not [8].
2) Increases the Anticipation of Pleasure
When exposed to a rewarding stimulus, the brain responds by releasing more dopamine [9].
During these pleasurable situations, dopamine is released and stimulates one to seek out the pleasurable activity [10].
Pleasurable experiences such as sex, food, games or even drug abuse can increase dopamine release [9].
This brain reward system promotes survival of the species by rewarding behaviors necessary for continued survival such as seeking food, reproduction, shelter, and drink, etc. These activities that are essential to species survival and activate this pathway are associated with ‘feeling good’ [9].
Histamine, acting on histamine H1 receptors, can potentiate dopamine receptors to become more sensitive to dopamine [11]. Therefore, people with higher histamine levels or stronger H1 receptor activation may feel more pleasure from dopamine.
Dopamine does not mediate pleasure. It is known that the loss of dopamine does not affect the feeling of pleasure in humans or animals [12].
What it does is enhances the expectation of pleasure in humans [13].
This molecule is responsible for “wanting” something but not “liking” something (the hedonic effects of “liking” are mediated by opioids) [1, 12, 14].
3) Helps with Memory and Learning
Dopamine activity in the brain plays a big part in memory and learning [15]. It is essential for long-term memory storage and retrieval.
Dopamine signals important events. It helps you remember events that have motivational significance. This ensures that memories are relevant and accessible for future behavior [16].
Dopamine also plays an essential role in working memory. Working memory is the capacity to use information from short-term memory and use it to guide your own actions. Dopamine promotes nerve cell activity involved in working memory [17].
Serotonin also works with dopamine during memory formation. Activation of serotonin receptors can increase dopamine release in parts of the brain that are involved in cognition and memory formation, i.e. the prefrontal cortex and hippocampus) [18].
Dopamine release causes an individual to be motivated by certain stimuli. It can control and teach the individual different behaviors. Thus, it plays an important part in reward-driven learning [19].
4) Increases Attention and Focus
Dopamine has a role in focus and attention [10].
Dopamine dysfunction in frontal lobes can cause a decline in attention or even attention deficit disorders [20].
Moderate levels of dopamine (not too high or too low) improve the capacity of individuals to switch attention efficiently between tasks. Furthermore, moderate levels of dopamine direct attention more efficiently to stimuli that are relevant to ongoing tasks [21, 22].
5) Makes People More Social and Extroverted
Dopamine and its pathways are generally associated with more extroverted behavior [23].
For example, higher dopamine levels in 16 male patients were associated with a more extroverted personality [24].
There are several major dopamine-related genes that may affect how many dopamine receptors a person has, which in turn can influence the overall activity of the brain’s dopamine system.
For example, according to several studies, people who carry a ‘C’ allele for the DRD4 SNP rs1800955 show higher levels of extraversion and novelty-seeking [25, 26]. This DRD4 genotype is associated with a greater number of D4 dopamine receptors, and therefore may result in higher dopamine activity — but the available research is limited, and more studies will be needed to fully confirm this finding.
According to another study, carriers of the ‘A’ allele for the DRD2 SNP rs1800497 have up to one-third fewer D2 dopamine receptors [27]. However, unlike several other types of dopamine receptors, D2 receptors are inhibitory. This suggests that people with this DRD2 variant actually have higher overall dopamine activity levels (since their dopamine neurons are less inhibited by D2 receptors) [28, 29, 30]. Consequently, carriers of this allele were also reported to have significantly higher scores on trait extroversion, which fits in with what we know about these receptors [27].
(P.S.: If you’d like to know more about the DRD2 gene and its effects on the brain, we recommend checking out the SelfDecode blog post on DRD2.)
6) Important for Love (Romantic Attachments)
Intense romantic love is associated with the dopamine reward system. Dopamine is released through sex, touch, and orgasm, and plays a major role in the formation and maintenance of pair bonds [31, 32, 33].
When human subjects viewed photographs of people with whom they were in love, their brain activity patterns looked remarkably similar to those observed after cocaine infusions, or monetary reward, with heavy activation of dopamine-rich regions in the brain [34, 35, 36, 32].
Prairie voles mate for life. However, injecting prairie voles with dopamine blockers causes them to lose their monogamous tendencies – they fail to show any partner preference [31].
We know now that romantic bonding in humans is a result of the crosstalk between oxytocin, the “love molecule”, and dopamine [37].
7) Helps Establish Maternal Behavior
Maternal behavior is the result of a highly-motivated brain, that allows the female to flexibly adapt her caring activities to different situations [38].
Dopamine, along with oxytocin, plays a key role in maternal behavior [39].
Increases in dopamine levels are observed during nursing bouts [40].
Injections of dopamine receptor blockers result in deficits in maternal behavior in rats. On the other hand, improvements in dopaminergic signaling positively impact the deficits observed in maternal behaviors [40].
8) May Decrease Inflammation Due to Th1 and Th17 Dominance
Dopamine is shown to interact with the immune system. Treatment with dopamine can decrease inflammation and have other therapeutic effects [41].
The Dopamine 3 (D3) and D5 receptors are more inflammatory, while the D1, D2, and D4 receptors are more anti-inflammatory [42].
Although the immune effects are quite complex, overall, dopamine decreases inflammation. It reduces Th1 and Th17 dominance [42].
Low levels of dopamine would stimulate mainly the D3 receptor in T cells, favoring Th1-like responses and T cell activity. Moderate dopamine levels would stimulate the Dopamine D5 receptor as well, inhibiting T cell function. All of these increase inflammation [42].
Overall, higher dopamine levels decrease T cell response and inflammation [42].
DRD1 signaling inhibits the NLRP3 inflammasome. Inflammasomes are immune system receptors and sensors that induce inflammation in response to infectious microbes. DRD1 activation can potentially treat NLRP3-driven inflammation and diseases [43].
Higher levels of dopamine can help alleviate Rheumatoid Arthritis, IBD, and Lupus [44].
9) Influences the Sleep Cycle
Dopamine and its receptors play a part in controlling the sleep-wake cycle. Mainly, dopamine can help keep you awake and alert [45].
Dopamine D4 receptor combines with adrenaline receptors to block adrenergic receptor signaling and melatonin synthesis that is usually induced by the noradrenaline on the adrenergic receptor [46].
On the other hand, mice depleted of dopamine have a complete suppression of REM sleep. Activating dopamine receptors helped recover REM sleep. This indicates that dopamine is vital in regulating sleep [47].
Dopamine D1 receptor (DRD1) activation induces arousal and wakefulness. It also reduces slow-wave sleep and REM sleep [45].
DRD2 activation causes different effects depending on the levels of activation. Low levels of activation reduce wakefulness and increase Slow Wave (deep) and REM sleep. On the other hand, high DRD2 levels induce the opposite effect [45].
Compounds that block both D1 and D2 receptors reduce wakefulness and increase deep sleep [45].
DRD3 activation induces sleepiness and sleep in laboratory animals as well as humans [45].
Patients suffering from Parkinson’s disease may also have sleep disturbances because they have low dopamine [48].
10) Helps Increase Bone Strength
Dopamine has an effect on calcium metabolism and can help increase bone strength [49].
Mice missing the dopamine transporter (SLC6A3) gene have a weaker bone strength and less bone mass compared to normal mice [49].
Additionally, some male patients with excess levels of prolactin due to low dopamine can have a low bone mineral density (BMD). Dopamine treatment increased their BMD and strengthened their bones [50].
Also, dopamine treatment increased bone cell formation and mineralization in mouse cell culture [51].
11) Increases Creativity
Studies show that human creativity relies on dopamine. However, creativity is complex, and different aspects of creativity are affected by different dopaminergic systems [52].
Dopamine has first been associated with creativity after an observation that people with Parkinson’s develop artistic-like tendencies on dopaminergic therapy [53, 54].
A study shows that Parkinson’s disease patients treated with dopaminergic drugs show enhanced verbal and visual creativity [53].
Dopamine is involved in cognitive flexibility – one of the main components of creativity and creative thinking. Dopamine is also responsible for the openness to new experiences, another factor associated with creativity [52].
In healthy people, creativity was positively correlated with gray matter in dopamine-rich regions of the brain [52].
Various aspects of creativity were reported to relate to SNPs in COMT, DRD2 and DRD4 genes [52, 55].
A SNP in DRD2, rs1800497 T, is associated with reduced dopamine binding sites in the brain. This allele was related to higher verbal creativity in one study [56].
A polymorphism in DRD4 has a complex relationship with creativity. DRD4-7R is associated with impaired flexibility associated with low creativity. On the other hand, according to preliminary research, this allele is associated with higher novelty-seeking associated with greater flexibility and creativity [55].
Finally, the food we eat may affect the way we think [57]. Creativity in convergent (“deep”)-thinking tasks is promoted by the food supplement L-Tyrosine, a biochemical precursor of dopamine [57].
12) Speeds up Our Internal Clock
Our sense of time is far from constant. For instance, time flies when we are having fun, and it slows to a trickle when we are bored [58].
The brain dopamine system regulates our internal clock speed. Dopamine adjusts both time perception, in the seconds-to-minutes range, and the timing of motor acts (movement) [59, 60, 58, 61].
Increasing dopamine (by stimulants such as amphetamine) increases the clock’s speed, while dopamine receptor blockers (such as haloperidol) decrease the clock’s speed [61, 59].
The ‘internal clock’, is abnormally slow in Parkinson’s disease [62].
Time estimation is also impaired in patients with schizophrenia or patients with structural damage to certain brain regions, resulting from traumatic brain injury [59, 63].
13) Relieves Nausea
The stomach and intestines also have dopamine receptors. Dopamine acts through specific receptors to lower pressure in the gut. Drugs that increase dopamine activity stimulate the intestines to increase movement and function [64].
These drugs can help relieve nausea, vomiting, and even acid reflux [64].
Drugs that block the DRD2 receptor can decrease nausea, perhaps by increasing dopamine activity.
14) Inhibits Prolactin
Dopamine is the main inhibitor of prolactin secretion in the anterior pituitary gland [65].
It is important for prolactin hormone levels to be balanced. High prolactin levels (hyperprolactinemia) can cause reproductive problems in both men and women. Therefore, dopamine may help “fine-tune” the brain’s overall levels of prolactin [66].
15) Helps Movement
The basal ganglia, which is one of the largest and most important dopamine-based systems in the brain, is highly involved in controlling movement (among many other diverse functions). In order for the basal ganglia to function well, it requires sufficient dopamine release at the input nuclei [67].
Relatedly, it is believed that the loss of dopamine neurons in the basal ganglia is what is primarily responsible for the movement problems often seen in Parkinson’s patients, such as tremors and rigidity [68].
16) Helps Prevent Parkinson’s Disease
Dopamine is responsible for the communication between two regions in the brain, which is the substantia nigra and the corpus striatum. This is critical in producing smooth, purposeful movement. Loss of dopamine in this circuit results in impaired movement.
The nerve cells in this circuit produce dopamine. Parkinson’s disease occurs when these nerve cells become impaired and/or die.
When approximately 60 to 80% of the dopamine-producing cells are damaged and do not produce enough dopamine, the motor symptoms of Parkinson’s disease appear [68].
Low dopamine levels contribute to the painful symptoms that frequently occur in Parkinson’s disease [69].
17) Helps Prevent Nearsightedness (Myopia)
The biggest risk for nearsightedness in people is the amount of time spent indoors [70].
Scientists can induce myopia in animals by lowering the level of light [70].
The leading hypothesis is that light stimulates the release of dopamine in the retina, and this, in turn, blocks the elongation of the eye during development [70].
Injecting a dopamine-inhibiting drug called spiperone into chicks’ eyes could abolish the protective effect of bright light [70].
Retinal dopamine is normally ramped up during the day, which helps daytime vision. Researchers now suspect that under dim (typically indoor) lighting, the cycle is disrupted, and this leads to myopia [70].
18) Stimulates Sexual Drive
A person’s response to sex, just like other rewards, is largely dependent on dopamine (particularly the “mesolimbic” pathway) [71].
Dopamine (in the reward system and hypothalamus) plays a central role in sexual arousal, sexual motivation and penile erections [71].
Erections are dependent upon activation of both dopaminergic neurons (in the ventral tegmental area, or “VTA”) and dopamine receptors (in the nucleus accumbens) [71].
Drugs that activate dopamine D1/D2 receptors (“dopamine agonists“), such as apomorphine, have been shown to induce erections in men with both normal and impaired erectile function [71, 72, 73].
Some of the effects of dopamine on sexual behavior may be due to dopamine’s ability to decrease prolactin, a hormone that can inhibit sexual drive (particularly in men) [74].
“Dopamine Deficiency”
Associated Conditions
There are no symptoms associated with low dopamine levels per se. Instead, people with “dopamine deficiency” may only show symptoms of mental health or neurocognitive disorders. Your doctor will discuss your results with you. They may run additional tests to pinpoint the underlying cause of your low levels.
Low or high dopamine levels don’t necessarily indicate a problem if there are no symptoms or if your doctor tells you not to worry about it.
Conditions associated with low dopamine levels [75, 76]:
- Depression and other mental disorders
- Attention disorders (such as ADHD)
- Parkinson’s Disease
The following are the signs and symptoms of some conditions that can be accompanied by low dopamine (“dopamine deficiency”) [77, 78, 79]:
- Low Motivation
- Fatigue
- Weight gain
- Increased Appetite
- Low Libido
- Higher prolactin
- Anhedonia (lack of pleasure)
- Memory Problems
- “Brain Fog”
- Introverted personality
- Lowered ability to form romantic attachments
Although low dopamine levels are commonly described as “dopamine deficiency,” this can be misleading. Assessing dopamine levels in the brain is extremely difficult.
For one, no deficiency parameters have been established in the scientific or medical literature.
Secondly, dopamine levels can’t be directly measured. Even with indirect measurements (such as with brain imaging), dopamine levels may vary across brain areas and quickly change depending on many factors.
Takeaway
Dopamine is sometimes called the “happiness hormone,” along with serotonin. However, it would be more accurate to call dopamine the “pleasure-seeking” or “motivating” hormone. In fact, dopamine seems to be responsible for our internal drive and flow states.
Without dopamine, we would probably not experience creativity, arousal, full wakefullness and focus, romantic love, or socialness. Dopamine is not the only neurotransmitter orchestrating these behaviors, but it seems to be a much needed one.
Limited research also suggests that “dopamine deficiency” might be linked with symptoms like fatigue, low motivation, and a lack of pleasure. This is plausible, but it hasn’t been proven.
Future studies should determine if low dopamine activity or levels in certain areas of the brain can cause any health problems.
