Neurophysiology 101

Dopamine is perhaps best known as the “pleasure” neurotransmitter, because it’s the currency used in the nucleus accumbens, or the part of the brain known as “the pleasure center.” It’s also one of the catecholamine neurotransmitters: its progeny are norepinephrine and epinephrine (better known as adrenaline). Together and when in balance, the catecholamines are responsible for excitement, joy, and the ability to focus and think clearly.

Acute Stress Raises Dopamine

Let’s revisit the primary stress hormone, cortisol. Acute stress causes the release of adrenaline (see above). Once the stressful event is over, cortisol takes over to clean up the mess left in adrenaline’s wake: it’s anti-inflammatory, immunosuppressive, and it also improves stress tolerance. When cortisol binds to its receptor (the glucocorticoid receptor, that is), it also triggers the release of dopamine in the prefrontal cortex. The prefrontal cortex is the part of the brain associated with focus and executive functioning, and dopamine is the biochemical currency there, too. This makes sense: in a crisis, you want plenty of dopamine in the prefrontal cortex to help you think your way out of the problem. (Plenty, but not too much: excessive dopamine leads to overthinking anxiety, and thus, decision paralysis. Far too much of it can lead to schizophrenia and hallucinations.)

Chronic Stress Depletes Dopamine

But remember, the body is always looking to create balance. While acute stress raises dopamine levels in the prefrontal cortex, chronic stress depletes it. This is in part because the mechanisms that break dopamine down get upregulated (increased) when there’s a lot of dopamine floating around—such as when you’ve been stressed out for awhile. Dopamine transporters also decrease in chronic stress. It also doesn’t help that dopamine is the precursor to adrenaline: the first hormone released in a “fight-or-flight” situation. What dopamine you might have had gets used up, and the extra dopamine released in response to high cortisol levels gets broken down faster, too.

Low Blood Sugar Depletes Dopamine

There’s yet another reason why chronic adrenal fatigue (low cortisol) can deplete dopamine, involving blood sugar. One of cortisol’s jobs is to make sure blood sugar levels remain stable between meals. If cortisol is low, blood sugar becomes unstable, and drops between meals. Low blood sugar means low insulin. Low insulin means low dopamine. Here’s why.

We’ve traditionally thought of insulin as merely allowing glucose into the cells. But it also allows amino acids from the protein in our diet, such as dopamine precursors (phenylalanine and tyrosine) to cross the Blood Brain Barrier (BBB). When insulin is too low, this doesn’t happen efficiently, and you can’t get the dopamine precursors into the brain. (If insulin is too high, you have a similar effect: this is insulin resistance. You might have plenty of insulin in this case, but its signals are far less effective.)

This is one of the big causes of emotional eating: a craving for sugar may really be a desire to raise insulin, in order to raise dopamine. (You may also be trying to raise serotonin this way, too—its precursor, tryptophan, also requires insulin to cross the BBB.)

Are You Low in Dopamine?

Low dopamine symptoms include poor motivation, dullness or lack of pleasure or excitement, mood swings, poor concentration and focus, poor memory, sugar and caffeine cravings, and poor stress tolerance.

If this is you, consider:

  • Are you low in insulin? If you’ve recently started a very low carb or ketogenic diet, dopamine depletion can occur in some people. If you’re low in insulin because you’re hypoglycemic, the best approach is to eat frequent small meals to stabilize blood sugar (and thus, insulin).
  • Are you insulin resistant? If this is you, lowering total insulin levels in order to improve insulin sensitivity is the way to go!
  • Are you low on dopamine building blocks? The amino acid precursors for dopamine are tyrosine and/or phenylalanine. These are found in meat, cottage cheese, eggs, almonds, bananas, nuts, and whole grains. Tyrosine and phenylalanine also need a few cofactors to turn them into the catecholamines, including zinc, B6, folate, iron, Vitamin D, and copper. You can also take Tyrosine and Phenylalanine amino acids directly, but there are some contraindications, and it’s possible to overdose; make sure you check with your health care practitioner that none of them apply to you before trying this.
  • Are you taking too much manganese? It’s rare, but excessive manganese can deplete dopamine.
  • Are you hypothyroid? The hypothalamus produces TRH, which tells the pituitary to make TSH, which tells the thyroid to make T4. Healthy TRH levels also stimulate the release of dopamine, suggesting that the opposite may also be true: low thyroid may also lead to low dopamine, and many studies suggest that this is the case. Additionally, dopamine and thyroid hormone also share an amino acid precursor: Tyrosine. If tyrosine is low, there likely won’t be enough to go around for both thyroid hormone and dopamine.
  • Are you taking high doses of 5HTP or melatonin? The amino acid tryptophan turns into 5HTP, which in turn becomes serotonin. Therefore, if you’re taking 5HTP, it’s likely in an effort to alleviate depression symptoms. Ironically, too much 5HTP can deplete catecholamines, and then you can end up with low catecholamine depression instead. Serotonin turns into melatonin, so too much melatonin can have the same effect.
  • And the big one… Are you chronically stressed? While adrenal support will certainly help indirectly by modulating cortisol levels, if you have low dopamine symptoms, you will likely need to supplement with its precursors, tyrosine and/or phenylalanine too. But of course, the real treatment is to mitigate your stress as much as possible.