Reward deficiency syndrome (RDS) is a psychological theory first noted by Kenneth Blum in 1996. It is characterized by reward-seeking behavior and/or addictions, stemming from genetic variations, most notably resulting from those carrying the D2A1 allele. People carrying the A1 allele tend to have insufficient numbers of D2 receptors in their brain, resulting in lack of pleasure and reward from activities that would provide others with pleasure.
This can result in addiction, mood disorders, compulsions, impulsivity, and other spectrum disorders. Since the normal “pleasure” neurotransmitters such as dopamine are lower among these individuals, they don’t feel as good as they should from normal activities. This leads them to seek out more extreme thrills such as addictive drugs or behaviors like gambling.
Due to the thrill seeking to feel the same level of reward as normal individuals, a person who is deficient in reward may finally feel some degree of pleasure from the addictive stimuli. Unfortunately, it is somewhat difficult to determine whether the reward-deficiency syndrome (RDS) was a result of genetic inheritance, or whether it was caused by stress or drug usage. Engaging in addictive behavior can inherently alter the pleasure center of the brain as well as neurotransmission.
It should be hypothesized that temporary cases of RDS can be caused by various drugs, stressors, or behaviors that can create changes within the brain. Therefore one could argue that the genetic D2 abnormalities could have been caused by drug usage or the addictive behavior in some cases. In other cases, it may be more likely that the genetics lead an individual to seek out an addictive substance due to lack of reward.
What causes reward deficiency syndrome? (Contributing factors)
In cases of reward-deficiency syndrome, researchers agree that there is usually a major genetic component. Throughout years of research, the goal has been to find a specific genetic variant that could be contributing to this condition. Early research regarding Reward Deficiency Syndrome discovered a link between carrying a certain allele (the “A1”) and alcoholism. Upon further investigation, this same allele was also associated with the development of other addictive, compulsive, and impulsive behaviors and disorders.
Examples of disorders influenced by this allele include (but are not limited to): ADHD, compulsive eating, obesity, pathological gambling, and Tourette’s syndrome. Although there may be multiple genetic factors that contribute, prominent researcher Kenneth Blum has determined that RDS is more likely among those with a specific A1 allele. Those carrying the A1 allele tend to have a significantly fewer number of D2 receptors in their brain. Therefore they cannot experience pleasure to the same extent as people without this gene and seek out addictive behaviors as compensation.
- A1 Allele: Those carrying the A1 allele tend to have insufficient D2 receptor development. The A1 allele associated with reward-deficiency syndrome and is present in approximately 25% of the general population. Blum’s research has been able to pinpoint this specific allele being linked to addictions such as alcoholism among first-degree relatives and families. When this specific allele gets passed on, the kids who inherit it are naturally more susceptible to developing addictions.
- P300 waves: This is electrical activity in the brain that is common among alcoholics. The P300 waves have been measured among sons to alcoholic fathers, and even from a young age, there is a significant increase in this “positive 300-millisecond” wave. This specific brain wave is also associated with some cases of RDS.
- Smoking: Among smokers, approximately 48% carry the A1 allele. Those who carried the A1 allele tend to smoke from an earlier age and have a more difficult time when they try to quit smoking. In people who had been able to successfully quit smoking or had never smoked at all, the prevalence of the A1 allele was significantly less.
- Gambling: Studies have determined that over 50% of those who are pathological gamblers carry the A1 allele. Those with more severe cases of gambling were more likely to carry the A1 allele. Furthermore, in a sample of men who had comorbid drug and gambling problems, the A1 allele was found among 76% – very significant.
- Chromosome #11: In the human genome, chromosome #11 is responsible for containing the gene that codes the D2 dopamine receptor; this is one of 6 total receptors.
- D2 receptors: In cases of reward deficiency syndrome, many neurotransmitter receptors have been investigated. Although there is generally a complex interplay between receptors that contribute to this condition, the most influential type is the dopamine receptor. Specifically the D2 dopamine receptor count tends to be reduced among those with RDS. This receptor is responsible for regulating attentional processes, motor control, motivation, and other important executive functions. Deficiencies in the D2 dopamine receptor can contribute to a variety of different disorders depending on the individual. Mathematically speaking, based on a predictive model called the “Bayes Theorem” – people carrying the A1 allele for the D2 receptor has approximately a 74% chance of developing a disorder as a result of reward deficiency syndrome. The specific disorder that a person develops will depend on other genetics and environmental influences.
- D4 receptor: It is believed that the D4 receptor may also have an influence in cases of RDS. Those who carry a certain variation of this gene are more likely to be thrill seekers and/or seek out reward. This receptor is believed to contribute to RDS significantly less compared to variants of the D2 receptor.
- Genetics: There is a major underlying genetic component to reward-deficiency syndrome. Kenneth Blum has determined that it can be passed on throughout generations and tends to run in families. For example, his research has shown that alcoholism can run in families as a result of those carrying a certain allele. Researchers believe that an inherent chemical imbalance or abnormal D2 activity influences how people react to certain events and situations. Among those with the A1D2 gene, it is believed that people experience alterations with the signaling processes in the reward center of the brain. This leads to feelings of anxiety, anger, and craving for a certain substance to help alleviate negative emotions. The addictive behavior such as using drugs, gambling, or alcohol makes the individual feel more “normal.”
How many less D2 receptors do those with the A1 allele have? Approximately 30% less than a person without it. It is hypothesized that the A1 allele is capable of reducing the expression of the D2 gene compared to individuals carrying the A2 allele. It is also possible that sites for the D2 receptors become altered among those with the A1 allele.
Essentially the reduced numbers of D2 receptors among those with the A1 allele results in reduced dopamine activity in reward centers. Those carrying the A1 allele may not feel pleasure from certain stimuli that brings others pleasure. It is also suggested that those with the A1 allele may have a tougher time coping with stress because their dopamine levels are significantly lower than average; dopamine tends to reduce stress.
Pleasure deprivation within the reward centers of the brain
Those afflicted with RDS are believed to experience a significant degree of pleasure depravation within the reward center of the brain. The severity of the condition is subject to variation based on the individual; other traits can play a role. Early research believed that reward-seeking behavior was an animal’s “learned” response to pleasurable stimuli.
Based on addiction research, dependency of various drugs such as alcohol, opiates, and stimulants all seem to have a similar biological basis in the brain. Addictions and reward-deficiency behaviors seem to stem from within the limbic system, specifically in two regions. These regions are known as the “nucleus accumbens” and the “globus pallidus” – and express reward among those with various addictions.
- Basic explanation: When D2 receptor activity is inadequate, activity levels of neurons within the nucleus accumbens and hippocampus becomes reduced. The individual feels unpleasant emotions and/or cravings for substances that will release dopamine, thereby providing temporary relief from these emotions.
- Cascade theory: Neurons responsible for releasing serotonin in the hypothalamus become excited and release enkephalin (an opioid peptide). This inhibits activity of neurons that release GABA (an inhibitory neurotransmitter) and dopaminergic neurons release dopamine which leads to a “cascade effect.”
Despite the fact that specific drugs have different effects on these reward regions, the final outcome is the same: doapmine gets released in the nucleus accumbens and hippocampus. Dopamine is considered the primary neurotransmitter associated with rewards in these particular regions. Serotonin in the hypothalamus, opioid peptides in the nucleus accumbens, and GABA in the ventral tegmental area can also have a lesser influence.
It is also believed that norepinephrine in the hippocampus can influence reward in an alternative pathway. Among individuals with normative functioning in the reward center, these neurotransmitters work collectively to either excite or inhibit excitement which helps create feelings of well-being and pleasure from life. Those with disrupted functioning of these neurotransmitters are thought to experience negative emotions and seek out substances that allow them to feel “reward.
Reward Deficiency Syndrome: Symptoms
Those with reward-deficiency syndrome tend to experience a variety of symptoms. These symptoms cannot necessarily be used to “diagnose” the condition because there is no specific diagnostic criteria. However, those who are aware of the condition may realize that they may be dealing with a case of reward-deficiency.
- Addiction(s): People with RDS may develop addictions as a way to feel engaged with life. Using drugs or gambling may make someone with this condition feel some degree of pleasure and/or thrill. This allows them to feel more “normal” and experience the same level of reward that others get from more mundane activities. Therefore certain addictions such as using drugs or gambling may become the focal point of the individual’s life.
- Lack of anticipation: Most people get excited while anticipating an event such as the first day on a new job, first day at school, going on a vacation, or a wedding. For most people, the excitement leading up to these events is significant. Those with reward-deficiency may not feel any excitement leading up to these major events. Essentially the excitement that normal people experience is heavily muted for those with RDS.
- Lack of pleasure: Due to the significantly reduced number of D2 receptors, many individuals don’t get a thrill from any activity. Certain events such as going on a big date, taking a vacation, or getting a good grade on a test may not make a person with RDS feel good. Some individuals with this condition may experience very little pleasure from “rewarding” activities, while others may experience none at all.
- Motivational deficits: People with RDS don’t just have a few less D2 receptors, they tend to be severely deficient compared to a normal individual. It is estimated that they have 40% fewer D2 receptors in specific areas of the brain such as the nucleus accumbens. This leads people to be less excited about pursuing goals and staying motivated. The functioning of their brain’s reward system is essentially nonexistant.
- Reduced arousal: People with RDS tend to lack arousal and excitement during activities that would be considered thrilling to a normal individual. Reduced levels of arousal are associated with less production of dopamine as well, which may also contribute to the RDS. Activities that result in high levels of stimulation such as using drugs may increase the person’s arousal and make them feel better.
- Thrill seeking: Based on Blum’s research, people with RDS tend to seek out the biggest thrills possible, given their circumstances. They do this because it allows them to feel pleasure and raises the amount of dopamine in their brain.
Self-Medicating with Reward-Deficiency Syndrome
Individuals with reward-deficiency syndrome often self-medicate with illicit drugs. This allows them to experience adequate levels of “pleasure” that they aren’t able to feel from other activities. It allows these individuals to function well and takes away their agitation, low mood, and anxiety.
Common addictions for those with RDS:
Note: Someone with RDS may have other addictions than simply what is listed above. Additionally a person with this condition may develop multiple addictions such as gambling and smoking.
Reward-Deficiency Syndrome Treatment
Fortunately there are some evidence-based pharmacological options that you can try if you have RDS. Researchers suggest that dopaminergic agonists such as bupropion, bromocriptine, and n-propylnor-apomorphine may be helpful in certain cases of reward-deficiency syndrome. They believe that whether these drugs are effective may be based on the specific expression of the D2 receptor gene.
They also suggest that individuals with the A1 allele should theoretically respond to D2 agonists. Furthermore they believe that these agonists may be most helpful for those with alcoholism and/or stimulant addiction. Those with the A2 allele who face addictions such as alcoholism will likely not respond well to the dopamine agonists. This is because their particular addiction is not associated with dysfunction of the D2 receptor.
Problems with “Reward Deficiency Syndrome” Theory
Although reward-deficiency syndrome is a well-accepted psychological model for explaining cases of addiction, not everyone agrees with it. Additionally researchers have suggested that there could be some problems associated with this theory.
- Drugs cause RDS: Chronic usage of drugs and/or alcohol may actually create a reward-deficient brain. Using drugs such as amphetamines or cocaine naturally lower the brain’s dopamine levels over time. This may lead to a drug-induced reward-deficient brain. It takes a lengthy period of abstinence before the individual’s brain is able to replenish dopamine levels and other homeostatic functioning. Receptors also can burn out or become desensitized as a result of the constant stimulation from drugs.
- Incomplete: Although there are some genetic ties to reward-deficiency syndrome, it remains a theoretical model. It is a model that many endorse and there is significant evidence to support the claim that certain individuals may be reward-deficient as a result of their genetics. Blum has extensively researched this condition and has made many breakthroughs that further support his model. Despite all the research suggesting that this condition exists, some may argue that the model is incomplete and inconclusive.
- Stress: High levels of chronic stress can cause polymorphisms of various genes that could contribute to reward-deficiency syndrome. Therefore someone who wouldn’t have otherwise become deficient in reward may experience this as a result of high stress levels. High stress can influence dopaminergic activity in the brain and also lead a person to develop an addiction.
- Thrill seeking isn’t always RDS: There are plenty of individuals who frequently seek out thrilling situations that don’t have reward-deficiency syndrome. Just because a person has lower levels of arousal or is an adrenaline junkie does not mean that the person necessarily is reward-deficient. Many people who seek out frequent thrills become excited for each one. If you are a thrill seeker, it doesn’t always indicate that you are reward-deficient.
Final thoughts on Reward-Deficiency Syndrome
Most people with true cases of RDS fail to seek out treatment because they are already self-medicating with illicit substances. In other cases, they may not even know that they have the condition or genetic predisposition. Without undergoing specific genetic testing to determine whether you have the D2A1 genetic variation, detecting the condition can be difficult.
Additionally, many people who are addicted to drugs may suspect that they have RDS, when in fact they do not have any genetic susceptibility or even RDS. Not all drug addicts or those with addictions necessarily have reward-deficiency syndrome. The term often gets thrown around loosely to describe individuals who are thrill seekers and/or who frequently use illicit drugs.
While many individuals with addictions may in fact have reward-deficiency syndrome, it cannot be assumed in every scenario. The criteria for diagnosing this condition can be difficult, but a psychiatric evaluation may help. Also if you get the genetic testing done and realize that you have the A1 allele, there is a good chance that RDS could be a culprit for your addictive behavior.