Neurotransmitters and Your Health
Excerpted from the “Institute of Education” section of the NeuroScience website (www.neurorelief.com)
Each neurotransmitter can be classified as either excitatory or inhibitory and each has specific functions in the body and potential roles relative to the understanding of certain diseases or symptoms. Understanding neurotransmitter functions will help you incorporate neurotransmitter testing into your practice.
Let’s start with the inhibitory neurotransmitters, GABA, serotonin, glycine and taurine:
GABA is the primary inhibitory neurotransmitter in the brain. Considered the body’s natural tranquilizer, GABA’s function is to regulate the output of excitatory neurotransmission. Elevated GABA is often observed in response to elevated excitatory activity. High GABA levels, in the presence of high excitatory activity, are associated with sleep issues, nervousness, anxiousness, panic attacks, irritability, hyperactivity, restlessness, low impulse control and seizures. Very low GABA levels may occur as a result of prolonged GABA depletion. High GABA activity without concurrent excitatory elevation results in reduced inhibition and sleepiness. GABA agonists include allopregnanolone, barbiturates, and alcohol.
Serotonin is an inhibitory neurotransmitter and plays a pivotal role in maintaining a balance between the excitatory and inhibitory neurotransmitters. Serotonin neurons innervate many regions of the brain; as such this transmitter influences many of the body’s processes. Low serotonin levels have been associated with a number of symptoms, including low mood, uncontrolled appetite,headaches, GI distress, anxiousness, irritability, sleep issues, chronic fatigue, premenstrual complaints, impulsivity, hypoglycemia, and insulin resistance. Excessive serotonin levels are somewhat uncommon, but have been observed in children with neurological issues and in patients with serotonin syndrome as a result of medication excess.
Glycine is an inhibitory amino acid that regulates excitatory neurotransmission primarily in the brain stem and spinal cord, much in the same way as GABA. Low urinary glycine levels have been noted in patients with low mood, while elevations are observed in response to high excitatory activity.
Taurine is an inhibitory amino acid that also regulates excitatory neurotransmission. Taurine is important in preventing the harmful effects of excess glutamate as well as maintaining fluid balance. Optimal taurine levels are important for healthy sleep and promoting calmness.
Now let’s review some of the excitatory neurotransmitters:
Glutamate is the body’s primary excitatory neurotransmitter. It is responsible for the majority of neurotransmission in the brain and is necessary for learning and memory. Excessive amounts of glutamate are associated with obsessive tendencies, headaches, low mood, developmental delays and excitotoxicity. Low levels are associated with fatigue and inborn errors of amino acid metabolism.
Norepinephrine, also known as noradrenalin, is an excitatory neurotransmitter that is responsible for most of the activity within the sympathetic nervous system. Norepinephrine neurons are most active during the awake state and are important for focused attention and memory. High levels are linked to feelings of aggression, anxiousness, emotional lability, mania, high blood pressure, immune suppression, stress and hyperactivity. Low levels are linked to lack of energy, focus, and motivation as well as poor memory, low mood, and fatigue.
Epinephrine, also known as adrenalin, is an excitatory neurotransmitter that is important for energy, and mental focus. Low levels can result in fatigue, lack of focus, and difficulty losing weight. High levels are observed in patients experiencing sleeping problems, anxiousness and high blood pressure. Hyperactivity can be seen with both high and low levels of epinephrine. Low epinephrine and norepinephrine can be indicators of adrenal stress and subsequent adrenal insufficiency.
Phenylethylamine, or PEA, is an excitatory neurotransmitter. Studies on PEA have found that it promotes energy and elevates mood. It is a lipid-soluble molecule that readily crosses the blood-brain barrier. Low levels are associated with fatigue, cognitive dysfunction, attention issues, and developmental delays. Research suggests that patients with low mood may have decreased PEA levels, while levels are increased in psychopathic subjects. Excessive levels have been linked to mental stress and sleep difficulties. High levels have also been implicated in headaches and the antidepressant effects of exercise.
Histamine is another excitatory neurotransmitter that serves a pacemaker like function within the brain. The firing rates of histamine neurons correlate with the body’s day and night rhythms. Research suggests that histamine also serves as a modulator of epinephrine and norepinephrine. High levels are associated with restlessness, stress, serotonin depletion, cigarette use, and active allergies or swelling. Low levels are associated with fatigue, low mood, antihistamine use, and l-dopa therapy.
Aspartic Acid is an excitatory amino acid synthesized from glutamate. Significantly elevated levels of this amino acid can be excitotoxic to neurons. Low levels have been linked to fatigue, whereas high levels have been seen to induce seizures in animals.
Dopamine can be considered either an inhibitory or excitatory neurotransmitter, depending on the receptors located in various areas of the brain. Dopamine neurons extend into regions of the brain which control movement, memory, and addiction. Low dopamine is associated with attention difficulties, hyperactivity, memory deficits, poor fine motor control and cravings. High dopamine has been observed in patients with paranoia, hhigh blood pressure, short-term memory problems and poor GI function. There are also dysfunctions in the dopamine system with developmental delay and addictions, which may manifest in either high or low levels of dopamine.
Urine testing as a valid assessment of neurotransmitter levels:
As mentioned earlier, the neurotransmitter test is not diagnostic for any particular condition. However, certain neurotransmitter imbalances are associated with various clinical symptoms. The value of testing urinary neurotransmitters has a long medical history and is rapidly becoming an increasingly accepted method of assessing a patient’s health. Urinary neurotransmitter testing has long been used as a bio-marker for pheochromocytoma, a type of adrenal tumor that is characterized by excessive catecholamine excretion. Neurotransmitter testing is also being used in the assessment of many psychological and developmental disorders. The non-invasive nature of urine collection, coupled with the body of scientific evidence supporting urinary analysis, makes neurotransmitter testing a valuable part of assessing patient health.
It is well established that there are relationships between a patient’s health and their urine neurotransmitter levels. For example, studies have shown that many patients with depression have low urinary serotonin and dopamine levels. Other studies have demonstrated elevated norepinephrine levels. Likewise, a study by Yehuda and colleagues in 1992, reported that patients with Post Traumatic Stress Disorder frequently have elevated urinary catecholamines.
Researchers are also using urinary neurotransmitter testing to evaluate the efficacy of various interventions. For example, a study by Takahashi and colleagues 1976, demonstrated that when depressed patients are treated with 5-hydroxytryptophan,those with greater increases in urinary serotonin had a better clinical response than patients who had a lesser increase in their urinary serotonin. This suggests that urinary serotonin levels correlate with the clinical response to oral 5-HTP.
While urinary neurotransmitter testing has extraordinary value in helping to identify the underlying neurochemicals that affect mental disorders, guide selection of potential treatment strategies, and monitor treatment regimens, the power in urinary neurotransmitter testing may lie in the ability to help prevent the manifestation of mental disorders. One study in particular by Delahanty and colleagues in 2005, showed that urinary epinephrine levels after a traumatic event may be associated with an increased risk of developing posttraumatic stress disorder.
Changes in urinary serotonin, dopamine, and glutamate levels have also been suggested as markers for neurobehavioral toxicology caused by environmental pollutants such as fossil fuels and heavy metals. Urinary neurotransmitter evaluations of this type may be of predictive value in determining when a psychiatric disorder is more likely to occur and as such may indicate when more careful observation or preventive strategies may be implemented prior to the development of the disease.
A recent study in rats by Lynn-Bullock and colleagues in 2004, supports the link between increased urinary serotonin levels and an improved clinical response by finding parallel increases in brain slice, plasma, and urine serotonin levels after dosing with oral 5-HTP. The link between factors in the urine and the brain is also seen when the effectiveness of mental stimulants like methylphenidate and dextroamphetamine can be predicted by the degree to which PEA increases in urine.In addition, therapies used to treat depression have been found to reduce the elevated urinary norepinephrine levels in depressed patients. This evidence suggests that urinary neurotransmitter levels correlate with changes in psychiatric conditions.