Dopamine in AD(H)D
Dopamine is a neurotransmitter that is involved in regulating motor activity, attention, inhibition, behaviour, cognition, and reward mechanisms. People with AD(H)D have been shown to have disturbances in dopaminergic signalling, possibly due to a genetic variation in dopamine transporters (DAT).
Pleasurable activities stimulate the release of dopamine in the brain, as does focusing on a particular task that is engaging enough to stimulate the brain. Dopamine deficiency helps us to understand why people with AD(H)D need more stimulation than is ‘normal’ to keep them engaged and interested, and why AD(H)D sufferers are more likely to engage in ‘risky’ behaviour.
When concentrating on a task, the working part of the brain becomes highly active. Other parts of the brain remain somewhat active and are responsible for creative thinking and making new associations. This ‘white noise’ can take over in a dopamine-deficient brain, effectively drowning out the main signal. The stimulant medication Ritalin is a dopamine re-uptake inhibitor, meaning that it blocks some of the receptors that bind to dopamine, so that more extracellular dopamine is available for use. Many of the symptoms of AD(H)D can be alleviated by normalising dopamine levels .
Natural Dopamine Boosters
Natural medicine can be a valuable adjunct or alternative to stimulant medication, or can help to reduce some of the side-effects of medication. Following are some herbs and nutrients that may be used to support neurotransmitter balance and especially dopamine deficiency:
L-theanine, an amino acid extracted from black or green tea, is known to increase dopamine, serotonin, and the inhibitory neurotransmitter glycine [2, 3]. Studies show that L-theanine induces alpha-brain wave activity, improves cognition and memory, and promotes feelings of deep relaxation .
An estimated 25-50% children and adolescents with ADHD suffer from sleep disorders . One study assessed the effectiveness of L-theanine extract on sleep quality in 98 boys with clinically diagnosed ADHD. The L-theanine group had significantly better quality of sleep measured by reduced nocturnal motor activity, on an actigraphy watch, when compared to placebo. L-theanine appears to improve sleep quality without causing daytime drowsiness.
It’s important to note that the amount of L-theanine in commercially available green tea is typically too low to have an effect and that green tea naturally contains some caffeine. For this reason, green tea is not a recommended treatment for children, but caffeine-free L-theanine extract is available in capsule or tablet form.
Bacopa monniera is a herb that is traditionally used in Ayurvedic medicine to treat mental health disorders and loss of intellect and memory . It is commonly used in both homeopathic and herbal formulations in the treatment of ADHD.
Bacopa has been shown to improve cognitive performance, memory, and behaviour in several clinical trials . The bioactive compound in Bacopa, known as bacoside, is shown to interact with neurotransmitter systems. There is evidence that bacoside increases both serotonin and dopamine levels, positively affecting mood, behaviour, cognitive function and memory.
Zinc is an essential cofactor for more than 100 enzymes required for the metabolism of carbohydrates, fatty acids, proteins and nucleic acids. It is required for the metabolism of many neurotransmitters, especially melatonin. Melatonin is directly involved in dopamine regulation, and indeed zinc deficiency has long been associated with ADHD .
Many studies have shown that response to stimulant medication is improved when zinc-deficiency is addressed in ADHD patients [1, 7]. Zinc has a high affinity with dopamine receptor binding sites. It effectively blocks dopamine re-uptake, increasing the availability of free dopamine in the brain, while simultaneously supporting the binding of stimulant medications to receptors .
Iron is another key mineral cofactor for dopamine production. Prolonged iron deficiency in young children can lead to permanently lower IQ, developmental delay and behavioural disturbances . Several studies have linked low serum iron and ferritin (iron stores) with ADHD [10-12]. Iron supplementation in iron-deficient children with ADHD has been shown to improve symptoms in some studies .
Vitamin D, once absorbed from the sun or consumed, is transported to the kidneys and liver where it is converted into an active hormone. The hormone then activates genes that stimulate the release of dopamine and serotonin. Vitamin D deficiency is linked to ADHD with studies indicating that children with ADHD have significantly lower serum levels of Vitamin D than other children [13, 14].
If you or your child has AD(H)D, it is pertinent to address any nutritional deficiencies that may be present to help normalise dopamine levels. Sometimes, a few minor dietary changes are all you need. However, a multi-modal approach may be required to address the unique needs of an individual with AD(H)D. Consult your doctor or naturopath for testing and advice.
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