Prevalence: Depression ranks fourth in importance of all causes of disease burden for the population of the planet and third in women. In the economically developed countries, depression rises to second place. Depressive disorders are common, occurring in all countries, at all ages, in both sexes and often in conjunction with other illnesses. Depression is a recurrent and potentially chronic and disabling condition. If a person has one episode of depression, he or she has a 50% chance of having another one, a 70% chance of another episode after two episodes, and a 90% chance after three episodes. If untreated, a depressive episode can last for 6 months or more. One in six people with chronic Depression commit suicide. These figures show how important it is to recognise and treat Depression.
The overall life-time risk of having a depressive episode is approximately 15% but the risk is not equal for everyone. The principal risk factors for the occurrence of depression and the risk factors associated with a poor prognosis have been determined.
Diagnosis: Despite its prevalence, depression is under-diagnosed and consequently under-treated. This is partly because depressed mood is often considered by many to be a character weakness and a natural response to negative events. Feelings of sadness or despondency are part of normal human emotion and may be the consequence of disappointments or failures. Clinically, however, depression denotes a disorder of mood that is distinct from normal emotions. This distinction is not always easy to appreciate which makes diagnosis so difficult.
Furthermore there is a considerable hesitation for patients to consult. There is often an important time lag between the first appearance of symptoms and a consultation with a primary care phycisian or a psychiatrist. The reasons for this delay and the final motive for a consultation make interesting reading.
Characteristics of depression: Although Depression is characterised by low mood, it is the sustained, pervasive feeling of misery, despair and hopelessness are the predominant features of depressive illness which differentiate it from normal feelings of unhappiness or sadness. Defining depression involves distinguishing it from normality by identifying a series of signs and symptoms.The most used diagnostic criteria are those of the Diagnostic and Statistical Manual (DSM-IV), the International Clinical Diagnostic criteria (version 10) (ICD-10) and the Beck Depression Inventory (BDI). These diagnostic criteria should not be confused with Depression rating scales such as the Hamilton Depression Rating Scale (HDRS) and Montgomery and Asberg Depression Rating Scale (MADRS) which are designed to measure the severity of the depressive symptoms. The core symptoms of major Depression are defined in the fourth edition of the DSM (DSM-IV).
Psychotherapy or Pharmacotherapy?
In 1989, the National Institute of Mental Health (NIMH) completed the most careful study ever done comparing the success rates of psychotherapy vs. antidepressant drug therapy in the treatment of major Depression.
Patients with major depression were assigned at random for 16 weeks to one of four treatments: an antidepressant drug (imipramine), a placebo pill (monitored by brief, supportive, weekly visits to a physician), interpersonal therapy, or cognitive behavioral therapy.
The interpersonal therapy focused on the immediate social context of the Depression and the depressed person’s relations with other people. The cognitive therapy focused on correcting the patient’s negative thinking, irrational guilt and pessimism.
Most patients in all four groups improved during treatment. The major findings were surprising:
- For the Less Severely Depressed Patients: (about 60% of the total) all four treatments were equally effective.
- Placebo therapy (weekly visits to a supportive physician to receive an inactive pill) was just as effective as weekly visits to a psychologist or psychiatrist for psychotherapy.
- Placebo therapy was just as effective as antidepressant drug therapy.
For the Severely Depressed Patients: (about 40% of the total) the antidepressant drug therapy was highly effective; for example, 76% improved on imipramine and only 18% on the placebo.
- Interpersonal therapy was moderately effective, but not as effective as antidepressant drug therapy. + For example, long-term interpersonal therapy (once a month) was directly compared with imipramine for ability to prevent recurrence of major Depression among severely depressed patients who recovered. The average time until a recurrence was two-and-a-half years for patients taking the antidepressant drug, a year-and-a-half for patients in psychotherapy, and ten months for those who had neither. + The interpersonal therapy provided no further help for patients who were already taking the antidepressant drug.
- Cognitive therapy, for these severely depressed patients, was ineffective (being no better than placebo).
- The National Institute of Mental Health study issued a warning. It concluded that only 16 weeks of psychotherapy or antidepressant drug therapy for major depression was insufficient since it resulted in very high relapse rates.
What are the important implications of this National Institute of Mental Health study?
- For Non-severe Major Depression: time-consuming or expensive psychotherapy or antidepressant drug therapy is not needed.
- Non-severe depression usually spontaneously recovers. According to one recent study, the average episode of major depression lasts 4 months. In another recent study, 40% of depressed patients recovered within three months, 60% within six months, and 80% within a year.
- If the average episode of major depression lasts 4 months, then for these mild cases, all that is required is seeing a therapist frequently for brief, supportive visits until the depression spontaneously recovers.
For Severe Major Depression: once there is major impairment in social or vocational functioning, antidepressant drug therapy must be given.
- For severe depression, antidepressant drug therapy is highly effective (for example, in the NIMH study, 76% improved on imipramine and only 18% on the placebo).
- For severe depression, antidepressant drug therapy must be given for at least 6-12 months, or even longer (since the NIMH study showed that only 4 months of antidepressant drug therapy for major depression resulted in very high relapse rates).
- It would be medical malpractice to give a severely depressed patient antidepressant drug therapy without some form of frequent, supportive counselling. + Severely depressed patients suffer greatly and are high suicide risks. It takes weeks before antidepressant drug therapy starts to work, thus these patients desperately need a caring professional who will emotionally support them and their family until their body recovers. + This supportive psychotherapy probably would be much like the interpersonal psychotherapy of the NIMH study, that is, very focused on resolving the immediate social problems burdening the patient.
Different types of depression: Several types of depression exist. From these classifications it is easy to understand that the exact diagnosis of any disorder is not always easy. Some diagnostic criteria are designed more particularly in order to try to differentiate between different types of depression or to differentiate depressive states and anxiety states. A specific depressive syndrome in which somatic symptoms predominate has been described as ‘masked depression’.
Depression in the elderly: Diagnostic criteria used in younger patients may not be directly applicable to depression in the elderly, and there is also marked heterogeneity in the presentation of depression in elderly patients. Although depressive symptoms are common in elderly patients, depression is often under-reported.
Comorbidity: Anxiety, psychoses (delusions), Obsessive-Compulsive Disorders and cognitive impairment are often associated with depression. The risk of relapse is increased in depressed patients with concomitant Anxiety disorders or a history of substance abuse. And relapse is more likely when major depression is accompanied by a non-affective disorder than when depression occurs alone. The recovery rate in patients with double depression (major depression with Dysthymia) is 39% compared to 78% in patients suffering from major depression alone.
Medical illness can trigger depression, and is associated with a poor prognosis in terms of response to treatment or the probability of relapse. Medical conditions commonly associated with depression in elderly patients include Parkinson’s disease, dementia, cerebrovascular disease and Myocardial Infarction and hearing loss.
Major depression and anxiety: Depression and anxiety frequently occur together and it is important to distinguish between the two conditions. Symptoms that distinguish depression from anxiety include loss of pleasure or interest, fatigue, and changes in weight or appearance. In addition, depressed patients tend to wake up in the early morning and are unable to get back to sleep; by contrast, patients with anxiety disorders often have trouble falling asleep but do not usually show early morning waking.
Brain imaging and biological markers: Although brain imaging can be useful in excluding possible organic causes of depressive symptoms, it is not, in itself, helpful in diagnosing depression. Despite intensive research for biological markers of depression, no specific diagnostic test can be recommended for detecting depression in clinical practice.
Conclusions: Depression is common and readily treatable, yet often goes unrecognised and untreated. Given the considerable morbidity and distress caused by depression, and the high mortality from illness or suicide associated with depression, there is a strong case for devoting greater attention to the diagnosis and subsequent treatment of the condition. Clearly, further research is needed to refine diagnosis; at the present time, an attentive and focused clinical interview remains the mainstay for the evaluation and diagnosis of depression. And most importantly, it is important that the stigma currently attached to depression (and many other psychiatric illnesses) be removed. In this way patients who will not hesitate to seek medical help, which is the first and limiting step in the process of recognising depression.
by Michel BOURIN
University of Nantes, France
Revision date: June 21, 2011
Last revised: by Dave R. Roger, M.D.