Neurons and Neurotransmitters
Your brain is a big bag of neuron cells -- nothing more, nothing less. Just as it isn't the
electrons themselves, but rather their pattern of arrangement in your system's RAM which stores
information in your computer, it isn't the neurons themselves which store information in your
brain, but rather the connections between them which make you who you are. Each neuron has some
number of dendrites, which are small appendages for receiving signals from other neurons, and
some number of axons, which are longer appendages for sending signals to other neurons. You may
already know that neurons aren't really physically touching each other. In fact, there is a
small gap between the axon of a neuron sending a signal and the dendrite of a neuron receiving a
signal. This small gap is the synapse. You've probably heard people talk about it before.
So, if the axon and the dendrite don't actually touch each other, how do they communicate across
the synapse? Neurotransmitters. Each neuron has a small store of neurotransmitters which it can
use for communication with other cells. Normally, When a neuron fires, it will release a
neurotransmitter through its axons, the dendrites on the other side of the synapse will react to
the presence of the neurotransmitter, and the message will have been delivered. After the
message has been delivered, the neuron sending the message will reabsorb the neurotransmitter it
originally emitted so that you don't have that chemical floating around in your brain, activating
neurons it didn't intend to activate. The process of reabsorption of the neurotransmitter is
known as reuptake. Reuptake is like garbage collection for your brain!
A Few Good Neurotransmitters
Most of what we know about neurotransmitters has been developed through observation about the
amount of a particular neurotransmitter in the brain of a person or other animal and the
condition of that person or animal. For instance, a high level of the neurotransmitter serotonin
has been linked to positive moods, whereas a low level of the serotonin has been linked to
depression and suicidal or agressive behavior. An increase of serotonin can make a person
sleepy, where a decrease in serotonin can contribute to obsessive compulsive behavior.
How does serotonin get to your brain? Well, right now you have the amino acid called tryptophan
in your bloodstream. Tryptophan competes with other amino acids in your bloodstream to enter
your brain cells. When you eat a diet high in carbohydrates, your body naturally produces
insulin, and the insulin clears amino acids other than tryptophan from your bloodstream, but
doesn't interfere with the tryptophan, and the end result is that more tryptophan enters your
brain cells where it is converted to 5-HTP (5-hydroxytryptophan) and finally to serotonin, which
is sometimes called 5-HT in nutritional literature. If you've ever experienced a mood elevation
from eating sweets, breads or pasta, it's probably because you've indirectly elevated your
Dopamine is the critical neurotransmitter which regulates feelings of pleasure and pain. High
dopamine levels are responsible for people with extremely active sex drives, and low dopamine
levels cause sexual indifference. Dopamine also appears to be critical for smooth body
movements, as Parkinson's disease is caused by a dopamine deficiency. Dopamine is also necessary
for memory and reason, as individuals with low dopamine levels have trouble clearly remembering
events and following a logical train of thought. A diet high in Vitamins E and C seems to
increase the amount of dopamine in the brain, where Vitamin B6 and high protein diets seem to
decrease the amount of the tyrosine amino acid entering the brain, and therefore reduce dopamine
Norepinepherine, also called noradrenaline, is the neurotransmitter associated with alertness and
orienting functions. Norepinepherine is actually produced from dopamine. Low norepinepherine
levels have been linked with anxiety, lack of focus and fatigue. High norepinepherine levels are
associated with the body's natural "fight or flight" reflex in stressful situations. The higher
levels of norepinepherine seem to aid mental focus and increased muscle performance. The dietary
strategies for increasing or decreasing norepinepherine seem to be similar to those helping in
the control of dopamine, as the production of both neurotransmitters are closely linked.
An imbalance of neurotransmitters can cause a variety of unfortunate mental states. Decreased
serotonin, particularly in combination with decreased dopamine, is a major cause of depression.
People with schizophrenia have high levels of both serotonin and dopamine, though there is some
question whether elevated amounts of both neurotransmitters is sufficient to induce schizophrenia
or whether it is merely a symptom of schizophrenia itself. Finally, dopamine is the key in
addiction. Any drug or process with affects dopamine levels to a significant degree,
particularly those which increase dopamine levels, are likely to be addictive. From one point of
view, there isn't much difference between the sex addict and the crack addict -- both are looking
to boost the level of dopamine in their brains.
Neurotransmitters and Your Lifestyle
There is a strong feedback loop between the neurotransmitters in your brain, which affect the
choices you make and the lifestyle choices you make affect the neurotransmitters in your brain.
For instance, we see that alcohol not only causes an
increase in dopamine, but also causes a burst in the serotonin released by your neurons. This
serotonin burst accounts for the euphoric alcohol "buzz". However, once the buzz fades, your
serotonin levels are lower than they were when you started drinking, leading you to drink again
and again, forever seeking the heightened serotonin levels of that first drink. There are a few
conflicting theories on the relationship between serotonin and alcoholism. Chronically low
serotonin levels creates the chronic drinker who needs a drink every day to maintain a positive
mood, but some people appear to not release serotonin at all when drinking, and this tends to
create the binge drinker who doesn't know when to stop drinking because he can never get quite
Caffeine, unlike alchohol,
seems to lower serotonin levels somewhat, while at the same time significantly boosting dopamine.
Furthermore, caffeine will decrease your appetite for carbohydrates, further cutting off your
brain's source of serotonin. If your serotonin levels are already quite low, caffeine will only
make your situation worse! Feeling down on days where you've had a few cups of coffee? You
probably have less serotonin than you feel comfortable with.
Nicotine, as found in
cigarettes, stimulates the release of all three neurotransmitters introduced above: serotonin,
dopamine and norepinepherine. It's particularly interesting to note that the increase of
serotonin associated with nicotine is the cause of smoker's decreased appetite, and the decreased
serotonin levels encoutered during nicotine withdrawal is the cause of increased appetite amoung
smokers who have recently quit smoking.
Marijuana, the mostly commonly
used illegal drug in the United States, is just as effective as alcohol at causing a burst of
serotonin to be released to your brain, and this serotonin burst followed by serotonin
deficiency is the reason many depressed persons are attracted to marijuana and also the reason
why marijuana can increase the severity of depression. Interestingly, marijuana seems to
have no significant effect on dopamine levels, and this is the reason why many classify marijuana
as a non-addictive substance.
Cocaine is an interesting
drug, biochemically speaking. Not only does it cause a burst of serotonin and dopamine, it also
blocks dopamine reuptake! As we discussed above, reuptake is the process responsible for
cleaning out unwanted neurotransmitters from your brain and dopamine is the neurotransmitter
active in the addictive process, so those of you who have never tried cocaine can imagine just
how addictive a cocaine high could be. Cocaine is not a drug to be taken lightly.
One can think of Ecstacy as the
anti-cocaine. Where ecstacy doesn't seem to affect dopamine levels much, it is the most
effective narcotic for releasing serotonin. Ecstacy actually enters your serotonin containing
neurons through the reuptake process and causes those neurons to release all of their serotonin
at once. The intense euphoria of ecstacy is caused by the entire serotonin contents of your
brain floating around, all activating your serotonin-sensitive dendrites at the same time. The
down side of the ecstacy high is that you've depleted all of your serotonin in one burst, and you
can experience depression due to decreased serotonin for as long as a week after the high. This
is why ecstacy is particularly dangerous for those depressive individuals with naturally low
serotonin levels. Because of the intense activity experienced by serotonin-containing brain
cells under the influence of ecstacy, the functioning of these neurons may be permanently
In our love lives, dopamine will drive us to attraction, but a lasting relationship will tend to
increase our serotonin levels. Interestingly, it seems that a series of short term relationships
can decrease serotonin levels, but increase norepinepherine. You never know, the people you are
attracted to might just be affecting your brain chemistry! Prayer and mediation will increase
your serotonin levels. This is particularly interesting, because it actually shows a reasonable
scientific basis for the healing power of prayer. This is related to the observation that
patterns of positive thinking will cause a release of serotonin, where patterns of negative
thinking will cause a release of dopamine.
Now that we've introduced a few neurotransmitters and their relationship with lifestyle, the
question remains, what is a person to do if his or her neurotransmitters are out of balance?
Well, by far, the biggest business of neurotransmitter adjustment -- aside from recreational drug
use -- seems to be the treatment of depression.
Prozac and other SSRIs (Selective Serotonin Reuptake Inhibitors) are the biggest news in
depression treatment in the last ten years. As you might guess from the SSRI descriptor, these
drugs block the reuptake of serotonin, just as cocaine blocks the reuptake of dopamine, such that
a patient ends up with free-floating serotonin in their brain, activating serotonin sensitive
neurons much more freely than naturally occurs. Some have argued that SSRIs are, well,
pathological in that the reuptake process is a necessary part of normal brain function, but
others find it a very useful treatment for some forms of depression, particularly in individuals
where reuptake happens too soon. (If you'll remember the garbage collection metaphor above,
think about using Java with the garbage collector turned off as a fix for a buggy garbage
collector which frees objects when there are still references pointing to those objects). In
recent news, August of 2001 was the month that the patent on Prozac expired, making way for many
cheaper Prozac alternatives which work just as Prozac. One unfortunate side-effect of SSRIs is a
decrease in dopamine levels. Patients on anti-depressants who complain of decreased sex drive,
problems with memory or fuzzy thinking are often reporting a decrease in dopamine.
MAO inhibitors (Monoamine oxidase inhibitors) are an older treatment for depression, but they
work by decreasing the body's MAO, which is responsible for the breakdown of serotonin and
norepinepherine. When the MAO decreases, serotonin and norepinepherine activate serotonin or
norepinepherine sensitive dendrites for a longer period of time, causing more brain activity in
those neurons. Interestingly, MAO is also responsible for the breakdown of dopamine, so a
patient on MAO inhibitors can actually experience an increase in dopamine activity coincident
with the increase in serotonin and norepinepherine lifetime.
One over-the-counter "herbal" remedy which has recently been gaining in popularity is 5-HTP.
When we introduced serotonin above, we mentioned that 5-HTP is the immediate chemical precursor
to serotonin. One wouldn't find pills containing serotonin very effective because serotonin
itself won't cross the blood/brain barrier, but since 5-HTP will, it can be a useful means of
increasing your neurons' stores of serotonin. 5-HTP is legel to sell as an herbal medicine in
the United States because it can be extracted from the African Griffonia Simplicifolia plant, but
other countries require a perscription or don't have 5-HTP available at all.
On a purely personal note, I've had several severe suicidal depressive episodes in my life, and
I'm currently taking one-hundred milligrams of 5-HTP every morning. I've found it to be quite
effective in treating my depression.
Awareness is Critical
Hopefully now you have a slightly better understanding of neurotransmitters and how they can
affect your life. If you think that you might have a neurotransmitter imbalance, the first step
is to try and clearly identify the problem. A visit to the doctor is always a good idea if you
suspect something is wrong. Tests can be run, and the problem can be verified.
Understanding what is wrong is the first necessary step toward fixing the problem.