Neurotransmitters and Thyroid Function

Neurotransmitters are chemicals made and stored in the intestinal region for use by the brain to help us deal with anxiety, panic attacks, depression, memory loss, etc. Neurotransmitters play a role in shaping who we are and how we perceive ourselves and the world around us. They influence our moods, memory and learning, self-esteem, anxiety levels, motivation, and more. I think this explains why some people who have been suffering for years with unresolved thyroid symptoms can become grouchy, angry, and pessimistic. That may reflect not who they really are, but instead their worsening brain health due to thyroid hormone deficiency.

There is no scientifically validated way to test neurotransmitter levels through lab testing. The best way is to assess your symptoms. Also, if you see symptoms in one area this does not necessarily mean your levels are low. It could be other areas of the neurotransmitter pathway are affected, such as neurotransmitter release, binding, or clearance. Also, various factors can affect neurotransmitter levels, including blood sugar imbalances or hormonal imbalances. Rarely, if ever, does poor neurotransmitter activity indicate an antidepressant deficiency.

The master neurotransmitters are Serotonin and Dopamine. Research shows that deficiencies or breakdowns in the pathways of either one impact thyroid health in specific ways, such as hampering conversion of T4 to T3 and slowing down the brain's communication with the thyroid. People with a deficiency will often have symptoms of depressed thyroid function with TSH below 1.8 and T4 below 6. In addition to classic thyroid symptoms, these patients suffer from symptoms of either a serotonin or dopamine deficiency or both.

I talk more extensively about neurotransmitters in my new book Why Isn’t My Brain Working? However, for quick reference you can review the symptoms below.


Acetylcholine is the learning and memory neurotransmitter. Symptoms of poor acetylcholine activity include:

  • Loss of visual and photographic memory
  • Loss of verbal memory
  • Memory lapses
  • Impaired creativity
  • Diminished comprehension
  • Difficulty calculating numbers
  • Difficulty recognizing objects and faces
  • Slowness of mental responsiveness
  • Difficulty with directions and spatial orientation


Serotonin is the joy and well-being neurotransmitter. Symptoms of poor serotonin activity include:

  • Loss of pleasure in hobbies and interests
  • Feelings of inner rage and anger
  • Feelings of depression
  • Difficulty finding joy from life pleasures
  • Depression when it is cloudy or when there is lack of sunlight
  • Loss of enthusiasm for favorite activities
  • Not enjoying favorite foods
  • Not enjoying friendships and relationships
  • Unable to fall into deep restful sleep


GABA is the “calm and relaxed” neurotransmitter. Symptoms of poor GABA activity include:

  • Feelings of anxiousness or panic for no reason
  • Feelings of dread
  • Feelings of inner tension and inner excitability
  • Feelings of being overwhelmed for no reason
  • Restless mind
  • Hard to turn your mind off when you want to relax
  • Disorganized attention
  • Worry about things you never had thought of before


Dopamine is the “pleasure and reward” neurotransmitter. Symptoms of poor dopamine activity include:

  • Inability to self-motivate
  • Inability to start or finish tasks
  • Feelings of worthlessness
  • Feelings of hopelessness
  • Lose temper for minor reasons
  • Inability to handle stress
  • Anger and aggression while under stress
  • Desire to isolate oneself from others
  • Unexplained lack of concern for family and friends

 This information comes from: Datis Kharrazian, DHSc,DC,MS.