Dr. Roxanne Dryden-Edwards is an adult, child, and adolescent psychiatrist. She is a former Chair of the Committee on Developmental Disabilities for the American Psychiatric Association, Assistant Professor of Psychiatry at Johns Hopkins Hospital in Baltimore, Maryland, and Medical Director of the National Center for Children and Families in Bethesda, Maryland.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
The causes of depression are complex. Genetic, biological, and environmental factors can contribute to its development. In some people, depression can be traced to a single cause, while in others, a number of causes are at play. For many, the causes are never known.
Currently, it appears that there are biochemical causes for depression, occurring as a result of abnormalities in the levels of certain chemicals in the brain.
These chemicals are called neurotransmitters.
The abnormalities are thought to be biological and
are not caused by anything you did.
While we still don't know exactly how levels of these
neurotransmitters affect mood, we do know that the levels can be affected by a
number of factors.
Heredity: Certain types of depression seem to run in
some families. Research is ongoing as to exactly which genes are involved
in depression. Just because someone in your family has depression, however,
doesn't mean you will. Sometimes, family members who were known to abuse
alcohol or other drugs were unwittingly trying to improve their mood (often
called "self-medication" by professionals). Likewise, you can become
depressed even if no one else in your family is known to have depression.
Personality: People with certain personality traits are more likely to become depressed. These include negative thinking, pessimism, excess worry, low self-esteem, a hypersensitivity to perceived rejection, overdependence on others, a sense of superiority or alienation from others, and ineffective responses to stress.
Situations: Difficult life events, loss, change, or persistent stress can cause levels of neurotransmitters to become unbalanced, leading to depression. Even events that tend to be major happy occasions, such as pregnancy and childbirth, can cause changes in hormone levels, be stressful and cause clinical depression, as in postpartum depression.
Medical conditions: Depression is more likely to occur with certain medical
illnesses. These "co-occurring" conditions include heart disease, stroke, diabetes, cancer, hormonal disorders (especially perimenopause or hypothyroidism,
known as "low thyroid"), Parkinson's disease, and Alzheimer's disease. While it does not appear that allergies cause depression or vice versa, people who suffer from nonfood allergies have been found to be somewhat more vulnerable to also having depression compared to people who do not have allergies.
Clinical depression should not be considered a normal or natural reaction to
illness.
Medications: Some medications used for long periods, such as prednisone, certain blood pressure medicines, sleeping pills,
antibiotics and even birth control
pills in some cases, can cause depression or make an existing depression worse. Some antiseizure medications, like
lamotrigine
(Lamictal), topiramate (Topamax), and gabapentin (Neurontin), may be associated with a higher risk of suicide.
Substance abuse:
While it has long been believed that depression caused people to misuse
alcohol and drugs in an attempt to make themselves feel better
(self-medication), it is now thought that the reverse can also be the case;
substance abuse can actually cause depression.
Diet: Deficiencies in certain vitamins, such as folic acid and B-12,
may cause depression.
Certain people are more likely to develop clinical
depression. The following are risk factors for depression in adults:
Risk factors for depression in elderly people
include those listed for adults. The following are especially important:
Co-occurring illnesses: These become much more important risk factors in the elderly because of the higher incidence of these illnesses in older people. Diseases with which depression is more likely to occur include heart disease,
stroke, diabetes, cancer, thyroid disease, Parkinson's disease, and
Alzheimer's disease -- all diseases that are much more common in elderly
people than in other age groups.
Medication effects: Like co-occurring illnesses,
medication use is much more common in the elderly. Depression is a side
effect of some medications in the elderly.
Not taking medication for medical conditions:
Some medical conditions, if untreated, may cause depression. An example is
hypothyroidism (low thyroid functioning).
