NAMI
National Alliance on Mental Illness
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Symptoms, Causes and Diagnosis

Symptoms

Depression can be difficult to detect from the outside looking in, but for those who experience major depression, it is disruptive in a multitude of ways. The symptoms of clinical depression usually represent a significant change in how a person functions. Sometimes individuals become so discouraged and hopeless that death seems preferable to life. These feelings can lead to suicidal ideation, attempts and death by suicide. The following are key areas where depression causes major changes in people.

  • Changes in sleep. Many people experience difficulty in falling asleep, waking throughout the night and/or awakening an hour to several hours earlier than desired in the morning. Other people experiencing depression will sleep excessively–for much longer than they used to.
  • Changes in appetite. Many people in the midst of depression experience a decrease in appetite, and sometimes, noticeable weight loss. Some people eat more, sometimes resulting in weight gain.
  • Poor concentration. The inability to concentrate and/or make decisions is a scary aspect of depression. During a severe depression, many people cannot follow the thread of a simple newspaper article or the plot of a 30-minute TV show. Major decision-making is often impossible. This leads depressed individuals to feel as though they are literally losing their minds.
  • Loss of energy. The loss of energy and profound fatigue often affects people living with depression. Mental speed and activity are usually reduced, as is the ability to perform normal daily routines. If you are living with depression, you will likely find that you response to your environment much more slowly.
  • Lack of interest. During depression, people feel sad and lose interest in usual activities. You might even lose the capacity to experience pleasure. For instance, eating and sex are often no longer appealing. Formerly enjoyable activities seem boring or unrewarding during depression and the ability to feel and offer love may be diminished or lost.
  • Low self-esteem. During periods of depression, people dwell on memories of losses or failures and feel excessive guilt and helplessness. “I am a loser” or “the world is a terrible place” may take over and increase the risk of suicide.
  • Hopelessness or guilt. The symptoms of depression often come together to produce a strong feeling of hopelessness, or a belief that nothing will ever improve. These feelings can lead to thoughts of suicide.
  • Movement changes. People who are depressed may literally look “slowed down” and physically depleted or, alternatively, activated and agitated. For example, a depressed person may awaken very early in the morning and pace the floor for hours.

Causes

The general scientific understanding is that depression does not have a single cause; it arises from multiple factors that may need to occur simultaneously. A person’s life experience, genetic inheritance, age, sex, brain chemistry imbalance, hormone changes, substance abuse and other illnesses all play significant roles in the development of a depression. It also may be that there is no observable trigger leading to the illness; depression may occur spontaneously and be unassociated with any life crisis, physical illness or other currently known risks.

Our current understanding is that major depression can have many causes and develop from a variety of genetic pathways. The occurrence of mood disorders and suicides tend to run in families. However, your genetic inheritance is only one factor. Identical twins share 100 percent of the same genes, but both identical twins develop depression only about 30 percent of the time.

Some proposed genetic pathways in the development of depression include changes observed in the regional brain functioning. For instance, imaging studies have shown consistently that the left, front portion of the brain becomes less active during depression. Also, brain patterns during sleep change in a characteristic way during depression. Depression is also associated with changes in how the pituitary gland and hypothalamus respond to hormone stimulation.

Additional factors that have been linked to depression include a history of sleep disturbances, medical illness, chronic pain, anxiety, attention-deficit hyperactivity disorder, and alcoholism or drug abuse.

We know that a biologically inherited tendency to develop depression is associated with a younger age of depression onset, and that new onset depression occurring after age 60 is less likely due to genetic predisposition. Life factors and events seem to influence whether an inherited, genetic tendency to develop depression will ever lead to an episode of major depression.

Certain aspects of life, such as marital status, financial standing and where a person lives, do have some bearing on whether someone develops depression, but it can be a case of “the chicken or the egg.” For instance, though depression is more common in people who are homeless, it may be that the depression strongly influences why any given person becomes homeless. We also know that long-lasting stressors like unemployment or a difficult marriage play a more significant role in developing depression than sudden stressors like an argument or receiving bad news.

Traumatic experiences may not only contribute to one’s general state of stress, but also seem to alter how the brain functions for years to come. Early-life traumatic experiences have been shown to cause long-term changes in how the brain responds to future fears and stresses. This may be what accounts for the greater lifetime incidence of major depression in people who have a history of significant childhood trauma.

Other proposed genetic pathways in the development of depression include changes observed in the regional brain functioning. For instance, imaging studies have shown consistently that the left, front portion of the brain becomes less active during depression. Also, brain patters during sleep change in a characteristic way. Depression is also associated with changes in how the pituitary gland and hypothalamus respond to hormone stimulation.

Other factors that have been linked to depression include a history of sleep disturbances, medical illness, chronic pain, anxiety, attention-deficit hyperactivity disorder, alcoholism or drug abuse. Our current understanding is that major depression can have many causes and develop from a variety of genetic pathways.

Diagnosis

The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) is the current reference used by health care professionals to diagnose metnal illnesses such as depression. This manual was first published in 1952 and has since gone through several revisions. The current edition was published in 1994 and lists over 200 mental health conditions and the criteria required for each one in making an appropriate diagnosis.

In the DSM-IV, depression is classified as a mood disorder. The DSM-IV's criteria for a major depressive episode (which needs to last longer than two weeks) include:

  • Depressed mood (such as feelings of sadness or emptiness).
  • Reduced interest in activities that used to be enjoyed.
  • Change in appetite or weight increase/decrease.
  • Sleep disturbances (either not being able to sleep well or sleeping too much).
  • Feeling agitated or slowed down.
  • Fatigue or loss of energy.
  • Feeling worthless or excessive guilt.
  • Difficulty thinking, concentrating or troubles making decisions.
  • Suicidal thoughts or intentions.

There is a strong possibility that a depressive episode can be a part of bipolar disorder. Having a physician make the right distinction between unipolar and bipolar disorder is critical because treatments for these two depressive disorders differ. The use of antidepressants, the cornerstone of treatment of major depression can sometimes activate manic symptoms or even worsen depressive symptoms, including suicidal thinking, in people with bipolar depression. At the same time, antidepressants do not appear to be particularly effective for treating bipolar depression. In major depression associated with bipolar disorder, mood stabilizers and psychosocial treatments-not antidepressants-have a strong evidence base and can often be effective. Speaking with a mental health care provider can help guide this process.

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