| bobwhelan 2004-08-30, 11:09 am |
| NEUROBIOLOGY
The basic cell of the brain and nervous system is called a neuron.
Neurons talk to each other by releasing neurotransmitters. There are
specific circuits of neurons in the brain that use specific
neurotransmitters, and studies over the last fifty years have begun to
identify which circuits and which transmitters are involved in
depression. Dopamine, norepinephrine, and serotonin are some of the
transmitters used in these 'mood circuits.' Antidepressant medications
affect the amount and duration of these transmitters. Note that they
don't actually affect neurons directly: rather they allow your own
natural transmitters to build up to higher levels.
Non-drug interventions usually work by having you 'exercise' those
mood circuits in certain ways so that you jump-start your brain into
adjusting those transmitter levels. Some therapies even cause your
brain to create brand new circuits so that depressive thoughts don't
become so stifling. If the brains of depressed people who took
antidepressants are compared with the brains of depressed people who
had only psychotherapy, the MRI (brain scan) images are very similar,
providing some evidence that there are multiple ways to cause the same
changes in the brain to relieve depression.
Scientific studies have also found other biological mechanisms to be
related to depression including: changes in the endocrine system
(i.e., the system in which chemical messages are sent through the
blood, such as the thyroid gland), genetics (e.g., one identical twin
is much more likely to be become depressed if the other has
depression), parieto-occipital oligodendroglial swelling (changes in
the cells which protect neurons in part of the brain), left frontal
cortical and subcortical hypoactivity (decreased activity in the part
of the brain just above your left eye), and changes to the ventricles
and basal ganglia (other structures of the brain).
Most depression is considered 'psychiatric' meaning that it occurs
independently of other disease processes that may be at work in the
body. However, sometimes certain diseases and drugs are responsible
for the changes in the brain leading to depression. Usually these
non-psychiatric types of depression have just one or two of the
features of depression, for example, just slowed movement but all else
is normal. If these medical problems are the cause, then if they are
treated, the depression will go away. Even so, the depression can
still be treated just like the 'regular' kind with certain
antidepressants and non-drug therapies.
Diseases in any of the following organs may cause depression: kidneys,
heart, lungs, thyroid gland, adrenal gland, parathyroid glands,
pancreas Infections: pneumonia, mononucleosis, AIDS Inflammation:
lupus, rhuematoid arthritis Neurologic: epilepsy, multiple sclerosis,
Parkinson's disease, stroke,brain trauma. In addition, many
prescription drugs can cause depression such as: steroids, oral
contraceptives, propranolol, reserpine, methyldopa Drugs of abuse:
alcohol, marijuana, hallucinogens, and amphetamine withdrawal, to name
only a few.
bobwhelan
"Studies have found that after 3 months of antidepressant
treatment between 50% and 65% of the people who take them
will be much improved. This compares
with 25 - 30% of people given an inactive "dummy" pill,
or placebo."
- The British Journal of Psychiatry
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