Stressful life events can contribute to episodes of depression. Genetics research indicates that environmental stressors (life events that trigger a stress response) interact with depression vulnerability genes to increase the risk of developing depression. A good example would be how stress in the form of significant loss, especially the death of a close family member or friend, often leads to depression in vulnerable individuals. Examples of other stressful life events include career crises, divorce, social isolation, and early-life deprivation, all of which can lead to permanent changes in brain function and increased susceptibility to depressive symptoms.
Depression frequently co-occurs with other physical illnesses, including heart disease, stroke, cancer, diabetes, and HIV, and can also increase the risk for subsequent physical illness, disability, and premature death. While it's normal to feel blue when you're diagnosed with a chronic illness and it can be depressing to have a condition that causes pain or limits your activities, feeling disheartened and sad is not the same as having clinical depression. Detecting and then treating depression often significantly contributes to improving the overall medical outcomes in those with chronic illness.
Some medications cause depressive symptoms as side effects; among them are pain relievers for arthritis, cholesterol-lowering drugs, certain medications for high blood pressure and heart problems, and bronchodilators used for asthma and other lung disorders. In addition, different drugs can interact in unforeseen ways when taken together. It is important that each physician and pharmacist knows all the different types and dosages of medicine being taken and discusses the possible side effects with the patient.
Genetics research indicates that vulnerability to depression results from the influence of brain chemistry imbalance acting together with environmental factors. Modern brain imaging technologies are revealing that in depression, neural circuits responsible for the regulation of moods, thinking, sleep, appetite, and behavior fail to function properly, and that critical neurotransmitters-chemicals used by nerve cells to communicate-are out of balance.
Research has revealed that depression can co-exist with anxiety disorders (e.g., panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, or generalized anxiety disorder). Studies have shown an increased risk of suicide attempts in people with co-occurring depression and panic disorder, the anxiety disorder characterized by unexpected and repeated episodes of intense fear and physical symptoms, including chest pain, dizziness, and shortness of breath. Rates of depression are especially high in people with post-traumatic stress disorder, a debilitating condition that can occur after exposure to a terrifying event or ordeal in which grave physical harm occurred or was threatened.
It is estimated that 25% of people with substance abuse suffer from major depression. The abuse of depressant drugs alcohol, narcotics, sedatives, and tranquilizers is closely linked to depression, especially in men.
Evidence suggests that depression runs in families, which may be either the result of genetics or family socialization. Those with close family members who are or have been depressed are about twice as likely as the average individual to become seriously depressed themselves. Still, just because a person has family members with depression does not guarantee that he or she will develop it. Similarly, a person may get depression even if no one else in their family has experienced it.
Nearly twice as many women (12%) as men (7%) are affected by a depressive illness each year. At some point during their lives, as many as 20% of women have at least one episode of depression that should be treated. The influence of hormones on depression in women the mood-altering effects of menstruation, pregnancy, childbirth, infertility, oral contraceptives, and menopause present significant contributing factors. Many studies also suggest that since women in this culture tend to experience losses more deeply, they can be more vulnerable to depression.
While some men with depression exhibit classic symptoms, studies suggest that most men with the condition have hidden depression. The influence of cultural expectations, for example, men are supposed to be able to rise above emotional pain, prompts many men to hide their depression--and their shame about it. Rather than the classic symptoms, men are more likely to reveal their depression in alcoholism, substance abuse, or antisocial behavior. Men are also at a significantly higher risk of completing suicides, which could possibly be related to not being able to express and seek treatment for their worsening depressions.
While it used to be that the elderly were the group most prone to depression, recent studies suggest that the post-World War II baby boom generation is currently at greatest risk. Researchers theorize this could be the consequence of growing up in 1950s and 60s America with its unprecedented rates of divorce and relocation which resulted in significant losses of family, friends and community. Other studies point to today's 40- and 50-year-olds having come of age during a time of record economic expansion and increased expectations of wealth and success. Risk of depression increases when a person experiences a huge gap between what they expect and what they actually get and since the enormous numbers of baby boomers also meant unprecedented competition for schools, jobs, and housing, many had to face (and continue to be affected by) unfulfilled expectations. Having to cope with the resulting years of disappointment, frustration, and loss of self-esteem throughout their professional careers could be a contributing factor in many baby boomers becoming increasingly prone to depression. It should also be noted that even those who achieve career success are by no means immune to depression. In today's high-pressure corporate world, the emotional price of staying on top can be quite high and can often lead to depressive symptoms.
More than 2 million of the 34 million Americans age 65 and older suffer from some form of depression. Depression is not, however, a normal part of aging. In contrast to the normal emotional experiences of sadness, grief, loss, or passing mood states, depression can be extreme and persistent and can interfere significantly with an elderly person s ability to function. Depression often goes undiagnosed and untreated in the elderly because it can be masked by or confused with other existing factors such as other illnesses, medications, coping with personal losses (loss of career, loss of physical vitality, death of close friends or family members, and cognitive deterioration associated with normal aging. Untreated depression leaves the depressed elderly at serious risk for suicide. Older Americans are disproportionately likely to commit suicide. Incidents of suicide are especially high among elderly men, who account for 81% of suicides of those over 65.
Depression in young people can go undiagnosed and untreated because the symptoms are too often viewed as normal mood swings typical of a particular developmental stage. Diagnosing and treating teens and children with depression is critical to preventing impairment in academic, social, emotional and behavioral functioning and allowing children to live up to their full potential. Large-scale research studies have reported that each year up to 8.3% of adolescents and 2.5 % of children in the United States suffer from depression. Profound trauma in childhood--abuse, a bitter divorce, the death of a parent or other deeply disturbing experiences--or having a seriously depressed parent significantly increase the risk for depression in teens and children. Depression in young people also frequently co-occurs with other mental disorders, most commonly anxiety, disruptive behavior, or substance abuse disorders, and with physical illnesses, such as diabetes. There is also evidence that depression emerging early in life often persists, recurs, and continues into adulthood, and that early, untreated depression can lead to more severe mental disorders in adult life.