Depression is a debilitating mood disorder that involves excessive sadness. According to the National Institute of Mental Health, almost 21 million adults suffer from a mood disorder each year, of which 14.8 million are affected by major depressive disorder. Psychiatrists use the Diagnostic and Statistical Manual of Mental Disorders fourth edition, also known as DSM-IV, to diagnose depression. Biochemical changes in the brain can trigger the onset and progression of depression.
Neurotransmitters in the Brain
The brain controls emotional and mental functioning. It is composed of billions of nerve cells called neurons that send and receive messages. Neurotransmitters such as serotonin, dopamine and norepinephrine are the chemicals within the brain that transmit messages from a pre-synaptic neuron across a space between neurons called a synapse to a postsynaptic neuron. Depression can occur when there are deficiencies in the production of these neurotransmitters in the brain, when these biochemical messengers are not able to bind to receptors on postsynaptic neurons to complete communication of the message, or when other chemicals or changes in the brain disrupt communication.
Nutritional Biochemistry
L-tryptophan and l-tyrosine are amino acids found in protein foods that produce neurotransmitters in the brain associated with depression. L-tryptophan produces serotonin, whereas l-tyrosine produces dopamine which in turn produces norepinephrine. Deficiencies of these amino acids in the brain can cause reduced production of neurotransmitters that can lead to depression.
The availability of l-tryptophan and l-tyrosine to enter the brain to produce neurotransmitters can be altered by diet. According to research by Dr. Richard Wurtman and colleagues at Massachusetts Institute of Technology, a diet that is high in protein and low in carbohydrate can reduce the availability of l-tryptophan and l-tyrosine from entering the brain because most protein foods have high amounts of branched chain amino acids that compete to enter the brain from the plasma. A diet high in carbohydrate and low in protein can increase the entry of these amino acids into the brain.
Vitamin B6 is needed to produce neurotransmitters and communicate with nerve cells. Scientists at the University of Manitoba in Canada found vitamin B6 deficiency is associated with low serotonin levels in different parts of the brain. According to Scientists at Cochin University of Science and Technology in India, vitamin B6 deficiencies can affect the ability of neurotransmitters to bind to receptors on nerve cells.
Hormones
A hormone is a biochemical substance that is produced by a cell or tissue called a gland, transported through the blood and stimulates an activity in a cell or tissue located in a different part of the body. Declining hormones in women and men due to aging is associated depression. According to the National Institute of Mental Health, women are vulnerable to depression during times when their estrogen levels change, such as after childbirth, before menstruation and during menopause, and men may have symptoms of depression when their testosterone levels are below normal. Scientists continue to study the relationship between hormones and depression.
References
- National Institute of Mental Health: The Numbers Count: Mental Disorders in America
- "American Journal of Clinical Nutrition"; Diurnal Variations in Plasma Concentrations of Amino Acids; R.J. Wurtman; Sept. 1979
- "Progress in Neuro-Psychopharmacology and Biological Psychiatry"; Decreased Brain Serotonin; Dakshinamurti, K.; 1983
- "Journal of Neuroscience Research"; Effect of Pyridoxine Deficiency on Serotonin and Dopamine Receptors; Paulose, C.S.; 1985
- National Institute of Mental Health: How Do Women Experience Depression?
