Chapter 22: Serotonin, Deep Limbic System

"Depression is known to be caused by a deficit of certain neuro-chemicals or neurotransmitters, especially norephinephrine and serotonin.  In my experience, this deficit can cause increased metabolism or inflammation in the deep limbic system, which in turn causes many of the problems associated with depression. . .  Because the deep limbic system is intimately tied to moods, when it is overactive the ensuing problems with depression snowball and affect all the other deep limbic system functions."

Daniel G. Amen, M.D.; From the book, Change Your Brain, Change Your Life:  The Breakthrough Program for Conquering Anxiety, Depression, Obsessiveness, Anger, and Impulsiveness, page 47

FUNCTIONS OF THE DEEP LIMBIC SYSTEM  (page 37)

• sets the emotional tone of the mind
• filters external events through internal states (creates emotional coloring)
• tags events as internally important
• stores highly charged emotional memories
• modulates motivation
• controls appetite and sleep cycles
• promotes bonding
• directly processes the sense of smell
• modulates libido 

 

PROBLEMS IN THE DEEP LIMBIC SYSTEM  (page 43)

• moodiness, irritability, clinical depression
• increased negative thinking
• negative perception of events
• decreased motivation
• flood of negative emotions
• appetite and sleep problems
• decreased or increased sexual responsiveness
• social isolation

"We thought that excessive activity in the part of the brain that controlled emotion might correlate with enhanced feelings of all kinds, not solely negative ones.  Yet we noticed, again and again, that when this area was overactive on SPECT, it correlated with the subject's depression and negativity.  It seems that when the deep limbic system is inflamed, painful emotional shading results.  New research on depression from other laboratories around the world has borne this out."  (page 39)

     SPECT Brain Scans 3D Active View

                      White arrows are pointing to the Deep Limbic System/Thalamus areas

These scans show hyperactive areas in the brain.  A normal scan shows increased activity in the front of the brain, the cerebellum, with all else being relatively quiet. 

NORMAL SPECT BRAIN SCANS

Scans are from the Amen Clinics

I believe my body does not make enough serotonin, and other neurotransmitters, because of a genetic predisposition.  The incidence of depression is high on both sides of my parents families.  The information on page 105 in, The UltraMind Solution, by Mark Hyman, MD was interesting to me.  He says the activity of any neurotransmitter can malfunction is some way.  Below are some of the reasons why serotonin levels go down.  I want to do all I can to help my antidepressant assist my body in creating more serotonin.

1.  A tryptophan-deficient or low-protein diet.  Tryptophan is the primary amino acid out of which serotonin is created.  No tryptophan equals no serotonin equals a very unhappy mood.  In fact, studies show that if you feed a group of people a mixture of amino acids without tryptophan you can induce depression within hours! 

2.  Stress and high cortisol levels (the stress hormone).  Cortisol increases the activity of enzymes that break down tryptophan.  That leaves less around to make serotonin.

3.  Anything that causes inflammation (such as food allergies, infections, toxins, or a high-sugar diet).  Inflammatory messenger molecules called cytokines such as interferon gamma stimulate the enzymes TDO and IDO, which break down tryptophan and force it into a pathway that makes the excitatory neurotransmitter glutamate, which kills brain cells.

4.  Simply not making enough serotonin.  This happens for many reasons.  You may not have enough of the building blocks (the amino-acid tryptophan) because you eat too much sugar and not enough protein as suggested above, or you may have genetic predispositions that make it more difficult for you to create the neurotransmitter in the first place.  Those who have an SNP (single nucleotide polymorphism) or genetic variation of the enzyme THP2 have an 80 percent reduction in ability to make serotonin.

5.  Blood-sugar imbalances (insulin resistance or prediabetes).  This condition comes from eating a processed-food, high-sugar diet.  It depletes your serotonin after a short spike, leading to mood swings.

6.  You may be deficient in vitamin B-6. B-6 is the helper or catalyst for the enzyme that converts tryptophan into serotonin.  Deficiency in B-6 is often caused by stress, alcohol, and medications like birth-control pills.

7.  Magnesium deficiency.  This is so common in our society because stress, caffeine, sugar, and alcohol all deplete magnesium, which in turn prevents the body from making serotonin.