At a primary level, humans are benefit-led, and actions are motivated by the rewards obtained. The brain has a reward system that facilitates actions, motivation, and reward/pleasure. The brain chemical that takes centre stage in the reward and pleasure system is dopamine. This intricate reward system uses dopamine as a form of communication.
How is dopamine produced?
Dopamine is produced from an amino acid called L-tyrosine. Amino acids are building blocks of protein. L-tyrosine is taken from the diet through protein rich foods or supplements. It enters the brain and gets converted to L-dopa which is converted to dopamine. Availability of L-tyrosine is essential for dopamine production .
How does dopamine work ?
Feel-good experiences such as eating your favourite food, having sex, and achieving academic or career milestones, activate dopamine release. Its effects reach the motivation and memory centre of the brain which reinforces repetition of the action to experience the rewarding feeling. It tells your body that this event is worth experiencing over and over storing this rewarding feeling as a memory. The reward system is fine-tuned such that dopamine is released when a reward is expected to further motivate you to take actions to achieve it.
Addictions and the brain: what changes?
Addiction is a psychological condition where the individual goes through phases of excessive consumption of an addictive substance like drugs, alcohol, or nicotine, which includes phases of use, abstinence, and relapse . Addiction is treatable and many treatments are available for a successful recovery.
During addiction, the dopamine system is sent into overdrive. Nora D. Volkow, the Director of the National Institute on Drug Abuse (NIDA), USA, presents a model of four circuits involved in addiction: reward, motivation, memory, and control. During addiction, the enhanced value of drugs increases in the reward, motivation and memory circuits and it overshadows the control circuit . This reinforces uncontrolled drive to seek pleasure derived from drugs. There is a strong bond between dopamine and drug addiction. Addiction stems from enhanced habit formation due to drugs increasing dopamine levels 3-5 times more than normal pleasurable activities , which strengthens the drive to seek them often.
As drug intake increases, a constant release of high amounts of dopamine forms a new threshold. Increased dopamine levels are needed to feel the same intensity of pleasure. As the brain adapts to this increase, the impact of dopamine dampens, fuelling further intake, thus forming the cycle of addiction . Due to dopamine’s role in motivation, drug-seeking becomes the main motivational drive for addicts.
Dopamine and addiction: the influence of drugs
Every drug impacts the dopamine system differently. Higher the dopamine release, greater is the euphoria (“high”) experienced. Faster the drug enters the brain, larger is the dopamine release and more intense is the reinforcing effect. . Drugs alter the dopamine system in 2 basic ways: increased release and decreased removal.
Drugs affect the dopamine system in the following ways :
- Alcohol takes under 6 minutes to reach your brain  where it increases dopamine release. It also indirectly increases dopamine by inhibiting the relaxing brain chemical (GABA) that regulates dopamine brain cells. This allows unrestricted increase of dopamine. Opiates like morphine and heroin also follow a similar path.
- Nicotine can enter the brain within 10-20 seconds of smoking . It increases the production of the enzyme (compound that speeds up a chemical reaction) that converts tyrosine to dopamine. It also increases release of dopamine from brain cells.
- Cocaine produces effects within 5 seconds and they last between 15-90 mins . It decreases the removal of dopamine, which prolongs dopamine’s effect. It blocks the transporters that carry dopamine away. Amphetamines also work this way.
- Marijuana (weed) enters the blood immediately, reaches peak levels within 6-10 mins and enters the brain . There, it increases production of dopamine and its release.
Addiction recovery: what is L-tyrosine’s role?
The good news is that addiction is reversible. The brain is a resilient organ and is capable of fixing the damage and dopamine imbalance caused by drugs. It can take just 14 days for brain areas to start repair work upon alcohol abstinence , while it may take 14 months for the dopamine system to return to near normal upon drug abstinence . Complete abstinence is often the goal of many addiction-recovery programs. Removal of alcohol, nicotine and drugs lowers dopamine below normal levels, leading to the negative side-effects experienced during withdrawal , which increase the chances of relapse.
One way to naturally increase dopamine levels is increasing L-tyrosine intake. It is important to note that L-tyrosine’s dopamine production conforms to the brain’s regulated dopamine system and is non-addictive. This is opposite to drugs’ forceful increase of dopamine production and its prolonged activation.
A study of recovering drug addicts who were administered a nutrient supplement containing tyrosine found that 6 days-supplementation decreased drug-withdrawal symptoms . An animal study of drug addiction also found that provision of a multi-nutrient supplement with high doses of tyrosine for 8 weeks decreased withdrawal symptoms and promoted higher abstinence rates . A study among men smoking 10-25 cigarettes a day who were provided a tyrosine-free drink during an abstinence phase found that depleted tyrosine levels lead to higher cigarette cravings . Similar results were found among abstinent alcoholics, where removal of tyrosine increased desire for alcohol intake . Contrasting results were found in a small study where smokers provided tyrosine-free drink during short term abstinence had lower motivation to obtain cigarettes due to reduced dopamine levels .
L-tyrosine: natural dopamine booster
Research on tyrosine supplementation for addiction recovery is limited but promising. L-tyrosine naturally and safely increases dopamine levels so rewarding and pleasurable experiences can be enjoyed. A review of 35 studies found that tyrosine supplementation improved cognitive functions in stressed individuals with low dopamine levels . Tyrosine intake can be increased as a part of a balanced high protein diet and can be safely supplemented to meet needs. Brain feed has created the world’s 1st natural 800mg tyrosine capsule from fermented corn. You can read more and buy it here for £29.99.
- Le Masurier, M. et al. (2005). Effect of Acute Tyrosine Depletion in Using a Branched Chain Amino-Acid Mixture on Dopamine Neurotransmission in the Rat Brain. Neuropsychopharmacology, 31(2), pp.310–317.
- Bromberg-Martin, E.S. et al. (2010). Dopamine in Motivational Control: Rewarding, Aversive, and Alerting. Neuron, [online] 68(5), pp.815–834.
- Guy-Evans, O. (2021). Brain Reward System - Simply Psychology. [online]
- Solinas, M. et al. (2018). Dopamine and addiction: what have we learned from 40 years of research. Journal of Neural Transmission, 126(4).
- Volkow, N.D. et al. (2003). The addicted human brain: insights from imaging studies. Journal of Clinical Investigation, [online] 111(10), pp.1444–1451.
- Wise, R.A. (2002). Brain Reward Circuitry. Neuron, 36(2), pp.229–240.
- Volkow, N.D. et al. (2007). Dopamine in Drug Abuse and Addiction: Results of Imaging Studies and Treatment Implications. Archives of Neurology. 64(11):1575–1579.
- Volkow, N.D. et al. (2011). Addiction: Beyond dopamine reward circuitry. Proceedings of the National Academy of Sciences, [online] 108(37), pp.15037–15042.
- Arias-Carrión, O. et al. (2010). Dopaminergic reward system: a short integrative review. International Archives of Medicine, 3(1), p.24.
- Hiremagalur, B. et al. (1993). Nicotine increases expression of tyrosine hydroxylase gene. Involvement of protein kinase A-mediated pathway. The Journal of Biological Chemistry, [online] 268(31), pp.23704–23711.
- Wise, R.A. et al. (2020). Dopamine and Addiction. Annual Review of Psychology, 71(1), pp.79–106.
- Bloomfield, M.A.P. et al. (2016). The effects of Δ9-tetrahydrocannabinol on the dopamine system. Nature, [online] 539(7629), pp.369–377.
- From The Glass To The Brain In Six Minutes. (2009). ScienceDaily. [online]
- Goriounova, N.A. et al. (2012). Short- and Long-Term Consequences of Nicotine Exposure during Adolescence for Prefrontal Cortex Neuronal Network Function. Cold Spring Harbor Perspectives in Medicine, [online] 2(12).
- Stein, S. (2022). How Long Does Cocaine Stay in Your System? (Blood, Urine & Saliva). American Addiction Centers [online]
- Chayasirisobhon, S. (2020). Mechanisms of Action and Pharmacokinetics of Cannabis. The Permanente Journal, 24(5).
- Volkow, N.D. et al. (2010). Addiction: Decreased reward sensitivity and increased expectation sensitivity conspire to overwhelm the brain’s control circuit. BioEssays, 32(9), pp.748–755.
- van Eijk, J. et al. (2012). Rapid Partial Regeneration of Brain Volume During the First 14 Days of Abstinence from Alcohol. Alcoholism: Clinical and Experimental Research, 37(1), pp.67–74.
- Volkow, N.D. et al. (2001). Loss of Dopamine Transporters in Methamphetamine Abusers Recovers with Protracted Abstinence. The Journal of Neuroscience, [online] 21(23), pp.9414–9418.
- Diana, M. (2011). The Dopamine Hypothesis of Drug Addiction and Its Potential Therapeutic Value. Frontiers in Psychiatry, 2(64).
- Munafó, M.R. et al. (2007). Effects of acute tyrosine depletion on subjective craving and selective processing of smoking-related cues in abstinent cigarette smokers. Journal of Psychopharmacology, 21(8), pp.805–814.
- Sun, H. (2010). Effects of Acute Tyrosine, Tryptophan, and Phenylalanine Depletion Treatment on Cue-Induced Alcohol Urging in Patients With Alcohol Dependence in China. [online]
- Venugopalan, V.V. et al. (2011). Acute Phenylalanine/Tyrosine Depletion Reduces Motivation to Smoke Cigarettes Across Stages of Addiction. Neuropsychopharmacology, 36(12), pp.2469–2476.
- Chen, D. et al. (2012). Neurotransmitter-precursor-supplement intervention for detoxified heroin addicts. Journal of Huazhong University of Science and Technology [Medical Sciences], 32(3), pp.422–427.
- Webber-Waugh, A. et al. (2017). Drug Seeking Behavior of Amphetamine Addicted Sprague-Dawley Rats Is Eliminated after Nutritional Supplementation. Journal of Behavioral and Brain Science, 07(12), pp.585–597.
- Jongkees, B.J. et al. (2015). Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands—A review. Journal of Psychiatric Research, 70, pp.50–57.