“Psychology Works” Fact Sheet: Depression

What is depression?

Almost everyone feels sad or “depressed” at certain times. Clinical depression (also called Major Depressive Disorder or MDD) is a more serious condition that is confirmed by the presence of at least five symptoms for at least a two week period.

The possible symptoms of Clinical depression include sadness, loss of interest in usual activities, changes in appetite, changes in sleep, changes in sexual desire, difficulties in concentration, a decrease in activities or social withdrawal, increased self-criticism or reproach, and thoughts of, or actual plans related to suicide.

Clinical depression may vary in its severity and its duration. In its extreme form Clinical depression can be life threatening and may require hospitalization.

Whereas Clinical depression is a more severe form of depression which can be fairly time-limited, Dysthymic Disorder (also called Dysthymia) is a less-severe, but more chronic type of depression.

Dysthymia is recognized when three of the symptoms listed above are present for at least two years. Some individuals also experience what is called “double depression”; when a person has ongoing Dysthymia, but from time to time also meets the criteria for Clinical depression.

Major Depressive Disorder is also distinguished from Manic Depression (also called Bipolar Disorder) in that in MDD the individual only experiences periods of depression, and potentially returns to normal functioning in between times. In Bipolar Disorder, however, the individual will cycle between depression and periods of hypomania or full manic problems (euphoria, high energy, lots of activity).

Approximately 1% of Canadian men and 2% of Canadian women are clinically depressed at any point in time and about 5% of men and 10% of women will experience clinical depression at some point in their life. Women are at about twice the risk of men to experience clinical depression. These rates of depression are fairly consistent in various countries around the world.

Depression is often a recurring condition, as a person who has had one episode of clinical depression is at high risk for repeated experiences, and this risk of recurrence increases with each subsequent episode. Prevention, early assessment and intervention are thus recognized as critical aspects of health care.

Although the causes of clinical depression are complex and vary from individual to individual,  a variety of factors increase the risk of a person experiencing clinical depression. Women may face an increased time of risk after childbirth.  Other risk factors include having a parent who has been clinically depressed, physical illness or ongoing disability, the death or separation of parents, major negative life events (in particular, events related to interpersonal loss or failure), pervasive negative thinking, physical or emotional deprivation, and previous episodes of depression. The most common framework is called the Biopsychosocial model, which incorporates biological, psychological and social categories of risk.

It is also increasingly recognized that some factors can increase resilience or reduce the risk of depression, such as regular activity, sound sleep, positive social relationships.  Models of clinical depression now often include both risk and resilience factors.

Some individuals experience depression in a regular seasonal pattern. Finally, some medical conditions and the effects of some medications can either look like, or induce, a depressive episode.

What psychological approaches are used to treat depression?

Given the large number of people who experience depression and its profound negative effects, psychologists have devoted considerable effort to study depression and develop effective treatments. These efforts have resulted in a number of treatments with evidence to support them. Many of these treatments emphasize one or more of the recognized risk factors discussed above.

Cognitive therapy is the most well-studied psychological treatment for depression and has the most consistent evidence to support its use.

Cognitive therapy involves the recognition of negative thinking patterns in depression and correcting these patterns though various “cognitive restructuring” exercises. Cognitive therapy also uses behaviour change strategies, and is also sometimes referred to as “cognitive- behavioral therapy”.

Cognitive therapy has been shown to successfully treat approximately 67% of individuals with clinical depression. The evidence suggests that cognitive therapy reduces the risk of having a subsequent episode of depression.

Behaviour therapy helps patients increase pleasant activities and overcome avoidance and withdrawal through efforts to become more engaged in the world.

Behaviour therapy also teaches strategies to cope with personal problems and new behaviour patterns and activities. Behaviour therapy is offered in individual or group therapy and has comparable success to cognitive therapy.

Interpersonal therapy is another treatment for depression, based on the idea that interpersonal stresses and dysfunctional relationship patterns are the major problems experienced in depression.

Interpersonal therapy teaches the individual to become aware of interpersonal patterns and to improve these patterns through a series of interventions. Interpersonal therapy has a success rate that is comparable to behaviour therapy and cognitive therapy.

Other psychological treatments exist in addition to the above treatments, and have promise in treating depression. These treatments have some evidence to support their use although they are not as well-established as the first three treatments.

Short-term psychodynamic therapy is a treatment which focuses on the identification of core conflictual themes in the way a person thinks about themselves or their interpersonal relations, some of which may be unconscious.

This treatment approach uses the therapeutic relationship as a model for other relationships and uses corrective experiences in therapy to lead to other changes in the depressed person’s life. Evidence suggests that the efficacy of this therapy approach is comparable to other established treatments for depression, although less research exists to make firm conclusions.

Reminiscence therapy is a treatment that has been developed for older adults with depression. It involves teaching people to remember times when the individual was younger and functioned at a higher level than as a depressed older adult.

Self-control therapy and Problem-solving therapy are treatments which combine some elements of cognitive and behaviour therapy for depression and teach better self-control and problem-solving behaviours in problem situations.

Scheduled exercise can also be used to treat depression.  Consistent evidence reveals that a regular routine (about 3 or more times a week, at about 30 minutes each time) of at least moderate aerobic exercise is associated with reductions in depression.

Biological treatments also exist for the treatment of clinical depression. These treatments are not offered by psychologists, but are typically provided by a family physician, psychiatrist or nurse practitioner. These treatments include drug therapies, electroconvulsive therapy and light therapy (the latter for people who suffer Winter-time Seasonal Depression, also called Seasonal Affective Disorder; SAD).

Psychological treatments are effective and safe alternatives to drug therapy for depression when provided by a qualified professional psychologist.

The established psychological treatments for clinical depression are roughly as successful as pharmacotherapy for depression.  In fact, psychological treatments often have significantly lower drop-out rates than pharmacotherapy (approximately 10% in psychological therapies versus 25-30% in drug therapy) which may be related to the fact that drug therapies for depression often have unpleasant side-effects.  There is also evidence that cognitive therapy in particular reduces the risk of relapse relative to those individuals who are treated with drug therapy.

Although the evidence is somewhat inconsistent at present, it does not appear that combining drug and psychological treatments significantly enhances the success of either of these treatments alone. However, some of the drug therapies may be effectively combined with psychological treatments which provide for longer term change. Further research on the costs and benefits of combined treatments is needed.

It is also worth noting that psychological treatments that focus on relapse prevention have been developed and tested. One model in particular, called Mindfulness Based Cognitive Therapy, has demonstrated the ability to reduce the risk of relapse, relative to treatment as usual or medications alone, especially for individuals who experience recurrent depression.

In summary, depression is a disabling and potentially chronic disorder. There are a number of successful treatments, which include psychological and biological treatments. Unfortunately, there is no clear way to know in advance to which treatment any one person with depression will respond.

It is important to identify and treat depression as soon as possible, to prevent its development into a chronic problem. Further, long-term and more severe depression is associated with increased risk of suicide, so timely intervention from a qualified and professional health care provider is recommended.

Where do I go for more information?

You can consult with a registered psychologist to find out if psychological interventions might be of help to you. Registered psychologists are regulated health professionals across Canada, and are required to meet educational, ethical and legal standards.  You can find a list of colleges and regulatory organizations at https://acpro-aocrp.ca.  Provincial and territorial associations of psychology also often maintain referral services; for this information go to https://cpa.ca/public/whatisapsychologist/ptassociations/. The Canadian Register of Health Service Providers in Psychology also has a list of providers and can be reached at http://www.crhspp.ca.

Other organizations in Canada also provide information abut depression.  Two notable sources include: Health Canada, at https://www.canada.ca/en/public-health/services/chronic-diseases/mental-illness/what-depression.html and The Canadian Network for Mood and Anxiety Treatments, at https://www.canmat.org/

This fact sheet was prepared for the Canadian Psychological Association by Dr. Keith Dobson, Department of Psychology, University of Calgary.

Revised: January 2021

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