Recently, I have been intrigued by the link between dopamine and narcolepsy. About a year ago, I had a blood test done for neurotransmitters, which indicated that I had normal serotonin, but low circulating dopamine. Nutritionally, this would indicate a deficiency in intake of L-tyrosine, or maybe a defect in the conversion to dopamine, or some other mechanism of dopamine release in the brain.
I didn’t really appreciate the bloodwork, until I realized there were signs of dopamine deficiency in family members on my mother’s side. My maternal grandfather has long suffered with restless legs syndrome, which can be caused by dopamine deficiency (and, also iron deficiency, which is important for dopamine storage and neurotransmission in the brain). Prior to going gluten free, I often struggled with restless legs, and still cannot take anti-histamines without feeling like my legs are going to dance off my body (anti-histamines are known to aggravate RLS).
I also am a runner, and thrive off of the runner’s high that I get. Running stimulates the release of beta-endorphins, which disinhibit dopamine transmission. In otherwords, running increases dopamine levels in the brain.
Though not well currently reviewed in the literature, dopamine and narcolepsy appear to have a close association with one another. Orexins act on dopaminergic nuclei, which express orexin receptors, indicating that orexin influences dopamine neurotransmission. In rats, infusion of orexin increases dopamine in the brain. Additionally, increases in orexin (and correspondingly dopamine) increased the time the rats spent awake. For narcoleptics, a deficiency in orexin neurons and orexigenic neurotransmission could cause a secondary dopaminergic neuron transmission deficiency. (i.e. – if orexin isn’t released, dopamine isn’t released).
From a therapeutic perspective, dopamine agonists have long been used to treat cataplexy and excessive daytime sleepiness associated with narcolepsy. Amphetamines (such as Ritalin) have long been used to reduce daytime sleepiness associated with narcolepsy, and amphetamines have been shown to increase levels of dopamine in the brain. In addition to the traditional stimulants, a more recently adopted wakefull-ness promoting drug, Modafinil, has also been shown to increase dopamine (and histamine) release, potentially by inhibiting the reuptake of dopamine.
In addition to conventional medicinal treatments, administration of the amino acid L-tyrosine, which is a precursor to dopamine, has been shown to positively affect symptom management in narcolepsy. Patients were administered 100 mg/kg/day (which is about 6 grams of L-tyrosine for the average person) for 6 months, and were reported to have complete remission of symptoms. Another study found that quantities of about 9 grams/day provided some wakefulness promoting effects, but it was not deemed a suitable alternative for use alone. There are limited reports of the use of L-tyrosine in scientific literature, however, and no studies have been published on it’s use recently.
Another compelling piece of the dopamine/narcolepsy connection comes from another neurodegenerative disorder, Parkinson’s disease (PD), whereby individuals lose dopamine-producing neurons in the brain. In fact, PD shares many features with narcolepsy including REM disorder and hallucinations as well as daytime sleep attacks. Indeed, it has been demonstrated that orexin-producing neurons are also lost in individuals with Parkinson’s disease, and narcolepsy has recently been implicated as a potential risk factor for PD, although it is unclear if this is an intrinsic risk factor, or if the treatments associated with narcolepsy (i.e. long-term amphetamine use) contribute to the deterioration of dopaminergic neurons and development of PD.
Due to the compelling literature evidence that dopamine and narcolepsy are interconnected, I recently began a regimen of 6 grams of L-tyrosine a day. I have had great results so far, and have noticed a significant reduction in daytime sleepiness and total time spent at night sleeping. I suspect that the effect will gradually wear off (I have been taking L-tyrosine for about 4weeks now), and I am interesting in speaking with others using L-tyrosine for it’s wakefulness-promoting uses; so, anyone out there?