This broad overview about major depressive disorder covers the signs and symptoms, diagnosis, and treatments.
Basic facts about depression and major depressive disorder.
Major depressive disorder is a serious medical illness. It’s more than just a feeling of being sad or “blue” for a few days. The symptoms persist and interfere with your everyday life. It can cause severe symptoms that affect how you feel, think, behave, and handle daily activities, such as sleeping, eating, or working.
It is an illness that can affect anyone—regardless of age, race, income, culture, or education. It is more common in women and often begins in teens and young adults.
There are effective treatments for depression, including psychotherapy (talk therapy), antidepressants, and others. If left untreated, though, depression may continue for weeks, months, or longer; and may lead to significant disability or death.
While the term “depression” or “depressed” is sometimes used as a general term for feeling sad, health care professionals are generally referring to a more severe and persistent form of depression, known as “major depression” or “major depressive disorder”, also sometimes referred to as “clinical depression”.
Depression in older adults is sometimes referred to by health professionals in different ways, such as “late life depression” or “late onset depression” or, more generally, “geriatric depression”. This is because some older adults may have a new diagnosis in older adulthood (over age 65); while others may have had depression at an earlier point in their life and there is now a recurrence.
According to the World Health Organization, major depression occurs in 7% of the general older population. This is probably a reasonable estimate of major depression in Canadian older adults, though it may be an underestimate. In a 2017 survey, 38% of Canadians said they had experienced persistent sadness and hopelessness for more than a couple of weeks; and in a 2016 survey, 40% said they had experienced feelings of anxiety or depression, but never sought health care for it.
Many older adults experience depressive symptoms that do not meet the full criteria for depression (see below under Symptoms).
Depression may be less well recognized in older adults, whether because some signs and symptoms are thought to be signs of normal aging; or because some older adults may not discuss how they are feeling with health care providers.
While the exact cause of major depressive disorder is not known, there are a variety of factors that may play a role, including genetic, biological, environmental, and psychological factors. As part of the assessment of depression, it is very important to rule out medical causes of depression.
In older adults, life changes can increase the risk for depression or make existing depression worse. Some of these changes include:
Sometimes depression may develop with no apparent cause or reason.
It is likely that these factors interact to determine the overall risk of developing this disease.
Signs and symptoms, depressive episodes, and the different types of depressive disorders.
A major depressive episode is defined as experiencing five or more of the symptoms below (one of which must be either depressed mood or loss of interest/pleasure in everyday activities) most days and most of the day for at least two weeks. These are a change from normal, are severe enough to interfere with a person’s day-to-day function, and are not better explained by a different disorder or condition.
However, depression in older adults may be hard to detect. Common symptoms such as fatigue, appetite loss, and trouble sleeping can be part of the aging process or a physical illness. As a result, symptoms of early depression may be ignored, or confused with other conditions that are common in older adults.
Two common forms of depression are:
Major depressive disorder often presents with distinct ‘episodes’ that are very different from the person’s normal mood and function; whereas persistent depressive disorder is much more chronic/longstanding, and people have typically felt a low-level of depression for many years. It’s also possible to have both disorders; and people with persistent depressive disorder are at increased risk of developing major depressive disorder as well (“double depression”).
Other forms of depression that are sometimes referred to:
Your health care provider may ask you questions to assess for a seasonal pattern, symptoms of psychosis, or a history consistent with bipolar disorder.
Common symptoms such as fatigue, appetite loss, and trouble sleeping can be part of the aging process or a physical illness.
Depression, especially in midlife or older adults, can co-occur with other serious medical illnesses, such as diabetes, cancer, heart disease, Parkinson’s disease, dementia, and others. These conditions are often worse when depression is present, and research suggests that people who have depression and another medical illness tend to have more severe symptoms of both illnesses.
Sometimes medications taken for these physical illnesses may cause side effects that contribute to depression.
Some symptoms of depression may occur when someone has delirium, a mental state in which a person is confused and has a change in the awareness of their surroundings. Delirium often occurs in hospital when an older adult has a serious illness, and may be associated with anxiety or depressive symptoms.
An adjustment disorder is an emotional or behavioural response to a stressful event or change in a person’s life circumstances. The person experiences more stress than would normally be expected, and the reaction causes significant problems in function. This might occur after losing your job, the loss of an important relationship, or as a response to a serious medical issue. Typically, when the stressor goes away, the person’s mood returns to normal. (Or the person adapts and copes with the stressor, and their mood bounces back.) While depressed mood may be a symptom of adjustment disorder, it tends to be less severe and persistent than major depressive disorder, with fewer other symptoms.
Substance use disorders like alcohol or opioid use disorders may be associated with signs and symptoms very similar to depression. It’s also possible to people to have both a substance use disorder and depression at the same time.
There are a wide range of other mental disorders that may co-occur with major depression, including substance use disorders and anxiety disorders like panic disorder and generalized anxiety disorder. It’s important for your doctor to ask about these other disorders, as you may need treatment for more than one condition at the same time. To learn more about anxiety disorders, you can view that topic here.
Assessment and diagnosis.
If you think you may have depression, you should talk to your doctor or nurse practitioner about depression screening, treatment options and/or a referral to a mental health professional. A proper assessment will review what has been happening with your mood, life circumstances, how you are managing day-to-day, and ask about other signs and symptoms you might be having. In addition, your health care provider will ask questions about your physical health, medications, substance use, and your medical history.
A depression screening is used to help diagnose depression, understand how severe depression may be, and help figure out what type of depression you have.
To be diagnosed with depression, an individual must have five depression symptoms every day, nearly all day, for at least 2 weeks. One of the symptoms must be a depressed mood or a loss of interest or pleasure in almost all activities.
Older adults with depression commonly experience sadness or grief or may have other less obvious symptoms. They may report a lack of emotions rather than a depressed mood. Older adults are also more likely to have other medical conditions or pain that may cause or contribute to depression. In severe cases of depression, memory and thinking problems (called pseudo-dementia) may be prominent.
During a depression screening, you’ll answer a standard set of questions. Your provider may ask the questions, or you may fill out a questionnaire to discuss with your provider later.
In general, the questions ask you about changes you’ve noticed in your:
An example of a standardized questionnaire is the PHQ-9 Depression Scale. This is a nine-item questionnaire based on the diagnostic criteria for major depression. It can function as a screening tool, an aid to diagnosis, and a tool to track symptoms and overall depression severity over time.
Your health care provider will follow-up on these screening questions to get more detail related to your symptoms.
You may also have a physical exam. There’s no lab test that can diagnose depression; but your provider may order blood tests to find out if another health condition, such as anemia or thyroid disease, may be causing depression.
As noted, a comprehensive assessment should include questions about your physical health, your medical history, what medications you’re taking, how you spend your time, and how you’re feeling. According to Ontario Health’s quality standard, a comprehensive assessment should also include the following:
The assessment should be done in a way that is respectful of diverse cultural, ethnic, and spiritual backgrounds. Information from the family and relevant third parties should be obtained when appropriate.
After other causes for depression like medical conditions or substances have been ‘ruled out’ or excluded you may be given the diagnosis of a major depression.
When you are diagnosed, your doctor may also specify whether your episode is mild, moderate, severe, or with psychotic features or with a seasonal pattern. Severity is based on the number of symptoms, the severity of those symptoms, and the degree of impact on everyday activities. Sometimes scoring on a standardized questionnaire like the PHQ-9 can also be used to estimate severity.
Mild: Few, if any, symptoms over-and-above what are needed to make the diagnosis, and the intensity of the symptoms and impact on function is still manageable.
Moderate: The number of symptoms, their intensity, and/or impact on everyday life are between “mild” and “severe.”
Severe: Many symptoms with a high degree of distress, and a marked impact on the ability to function.
Psychotherapy, antidepressants, and ECT.
There are effective treatments for depression, including non-medication treatments like psychotherapy (‘talk therapy’) and medications, typically antidepressants. Choosing the right treatment plan should be based on a person’s individual needs and medical situation under a provider’s care. It may take some trial and error to find the treatment that works best for you.
Treatment will also depend on a person’s preferences, the severity of their illness, associated symptoms, and availability/access to treatment options. In general, for a milder episode of major depression non-medication approaches may be recommended first. For moderate or severe depression many doctors recommend a combination of both medication and psychotherapy at the start of treatment.
Major depression is a serious illness associated with an increased risk of disability and death. People diagnosed with depression should typically receive treatment with antidepressants, psychotherapy, or both within 4 weeks for mild-moderate depression and within 7 days for severe depression.
Psychotherapy (sometimes called talk therapy) refers to a variety of treatments that aim to help a person identify and change troubling emotions, thoughts, and behaviours. Even when medication relieves symptoms, psychotherapy can help a person address specific issues. These might include self-defeating ways of thinking, irrational fears, problems interacting with other people, or difficulty coping with situations at home, school, or work.
Cognitive behavioural therapy (CBT) and interpersonal therapy (IPT) are the most common, best-evidence, psychotherapies for major depression. There are a few different variations on these types of therapy. They can be delivered on either a one-to-one or group basis; and are generally delivered over the course of about 12-20 sessions over 3 or 4 months (about an hour per session), though some have been designed for shorter durations such as 8 sessions. They are typically delivered by an appropriately trained therapist or physician in accordance with a treatment manual (validated, consistent approach to the therapy). CBT has also been shown to be effectively delivered remotely/virtually using technologies such as video conferencing (sometimes referred to as therapist-guided internet CBT or iCBT).
Benefits do not typically happen right away, so it’s important to give any form of psychotherapy enough time before determining whether or not it’s effective for you. Some people start to have initial benefits after 4-6 sessions, but full treatment of depression typically takes longer.
Consult your primary care provider if you are looking for a therapist. While some provinces and territories may provide psychotherapy as part of the provincial health plan, not all do. (Or it may be harder to access those that are funded by provincial or territorial health plans.)
‘Private’ psychotherapy can be quite expensive so, if you have private health insurance, check to see if your health insurance provider may have a list of recommended mental health professionals covered by your plan. If you are still employed and have benefits through work, check to see if your employer has some type of Employee Assistance Program (EAP or sometimes Employee Family Assistance Program or EFAP), which might include funding for a certain number of therapy sessions. Most EAP plans would not necessarily include a full course of evidence-based psychotherapy like CBT, though.
Once you have identified one or more possible therapists, a preliminary conversation can help you understand how treatment will proceed and decide if you feel comfortable with the therapist. It will also help to clarify if the therapist is using an evidence-based psychotherapy like CBT or IPT, and whether they’ve had specific training in those therapies.
Rapport and trust are essential. Discussions in therapy are deeply personal, and it’s important that you feel comfortable with the therapist and have confidence in their expertise.
A range of different self-management strategies can be effective complements to psychotherapy or medication treatments for depression, potentially resulting in faster and more complete improvement in symptoms. Pick ones that you like and that you think you can stick with.
For more information on nutrition, sleep, physical activity and Canada’s 24-hour movement guidelines view our content on promoting brain health.
There are many excellent online resources and programs. You can download a list of education and self-help resources, including websites, apps, books, and workbooks, from the resources areas for this topic (below and on the main topic landing page).
BounceBack is a free skill-building program from the Canadian Mental Health Association to help adults and youth 15+ to manage low mood, mild to moderate depression, anxiety, stress or worry. The programs are delivered online or over the phone with a coach. You will get access to tools to support you on a path to mental wellness. It is available in all provinces and territories. Visit bounceback.cmha.ca.
Wellness Together Canada is a free mental health and substance use resource that provides on-demand support; from basic wellness information, to one-on-one sessions with a counsellor, to participating in a community of support. Visit wellnesstogether.ca.
Peer support groups are groups that connect you with others who have lived experience of major depression. You can find support groups through your local mood disorders association through the Mood Disorders Society of Canada website.
Health care providers, such as a primary care provider or psychiatrist can prescribe medication for depression. The most common classes of medications used to treat depressive disorders are antidepressants. They don’t work immediately, and you may need to try more than one medicine before you can find the right one. However, in many cases medications do work faster than psychotherapy; and are frequently chosen as the first-line treatment for more severe depression.
Antidepressants are medications commonly used to treat depression. They take time to work—usually 4 to 8 weeks—and some depressive symptoms such as problems with sleep, appetite, or concentration often improve before mood improves.
Just like it’s not fully understood what causes depression, it’s not fully understood how antidepressants work to treat depression. They may help improve the way your brain uses certain chemicals that control mood or stress. We don’t have any reliable way to determine in advance which antidepressant will work best for which person, so you may need to try several different antidepressant medicines before finding the one that improves your symptoms and has manageable side effects. A medication that has helped you or a close family member in the past will often be considered.
If you begin taking antidepressants, do not stop taking them without talking to your health care provider. Sometimes people taking antidepressants feel better and then stop taking the medication on their own, and the depression returns or they have withdrawal from stopping too quickly. Antidepressant medications are not considered to be addictive, but your brain and body do get used to them after a few weeks, so they shouldn’t be stopped ‘cold turkey’.
When you and your health care provider have decided it is time to stop the medication, usually after a course of at least 6-9 months of being well, your health care provider will help you slowly and safely decrease your dose. Stopping them abruptly can cause withdrawal symptoms; it has also been shown to increase the risk of relapse.
Common antidepressants for major depression include selective serotonin reuptake inhibitors (or SSRIs) and serotonin and norepinephrine reuptake inhibitors (or SNRIs). While these medications are also known as “antidepressants,” they treat many different conditions, including anxiety disorders. In general, it is best to ‘start low and go slow’ with the dose of the medication; and know that your response to the medication may take a while, sometimes taking 4-6 or even 8 weeks for the start of symptom relief and up to 12 weeks or more for the medication to reach its full effect. It’s important to take your antidepressant medication as prescribed.
Some of the most commonly prescribed antidepressants include: escitalopram (Cipralex), mirtazapine (Remeron), sertraline (Zoloft), and venlafaxine (Effexor).
Because antidepressants can take several weeks to start working, it’s important to give the medication a chance before reaching a conclusion about its effectiveness.
With medication, longer-term therapy has been found to result in continued improvement in symptoms and helps to prevent relapse. For most people, medication therapy should be continued for at least 6-9 months after being well, depending on effectiveness and side effects. If your depressive symptoms have been more chronic, then your medication therapy should probably also last for longer to ensure a more complete and longer recovery period before considering tapering off of the medication. It’s important to try to treat all of your symptoms of depression; lingering symptoms may put you at an increased risk of relapse.
Many people who have had recurrent depression opt to stay on medication long-term; especially if they have had a good response and few side effects.
Common side effects of SSRIs and other antidepressants may include upset stomach, headache, or sexual dysfunction. The side effects are generally mild and tend to improve over time. People who are sensitive to the side effects of these medications sometimes benefit from starting with a low dose, increasing the daily dose very slowly, and adjusting when they take the medication (for example, at bedtime or with food). Doctors often prescribe lower doses of antidepressants to older people, and increase the dose more slowly than in younger adults.
As with any medication, there are risks and benefits, and you should discuss these with your healthcare provider. It’s very important to discuss potential adverse effects of the various types of medications with your healthcare team.
In some cases, people may experience worsening anxiety or rarely even increased suicidal thoughts or behaviour when taking antidepressant medications, especially in the first few weeks after starting or when the dose is changed. Because of this, people of all ages taking antidepressants should be watched closely, especially during the first few weeks of treatment. More common side effects include headache, irritability/restlessness, nausea, and diarrhea. The most bothersome side effects according to patient surveys include sexual dysfunction, drowsiness, fatigue, and weight gain. Most side effects tend to occur during the first week or two of treatment as your body gets used to the new medication; many will resolve in that time, but some – like sexual side effects or weight gain – may persist throughout treatment.
Sometimes if your antidepressant is at the right dose and you’ve been taking it for long enough, but your still experiencing depressive symptoms, your doctor may add another medication to try to improve your treatment. This is sometimes called ‘adjunctive treatment’, and the second medication might be another antidepressant, lithium, or a different class of medications such as an atypical antipsychotic medication like quetiapine (Sertraline). While these medications were initially used to treat other mental illnesses, they’ve also been used to help manage depression for many years.
There is not a lot of good-quality evidence at the moment to guide the selection of a specific antidepressant. Some types of drugs may work better for some patients, so people should work closely with a health care provider to identify which medication is best for them. Sometimes a medication may be chosen for potentially beneficial side effects; for example, if a medication is sedating or associated with increased appetite/weight gain, it might be a good choice for someone who is having problems with sleep and appetite. Or if a person has other medical conditions and is on other medications, it will be important to choose a medication that won’t aggravate any other conditions or have drug-drug interactions.
Choosing the right medication, medication dose, and treatment plan should be done under an expert’s care and should be based on a person’s needs and their medical situation. You and your provider may try several medicines before finding the right one.
Brain stimulation therapy, is also known as ‘neurostimulation’ or ‘neuromodulation’. The two main types of brain stimulation therapy are electroconvulsive therapy (ECT) and Repetitive Transcranial Magnetic Stimulation (rTMS).
ECT is considered one of the most effective treatments for severe depression. If medications do not reduce the symptoms of depression, ECT may be an option to explore. In some severe cases of depression where a rapid response is necessary or medications cannot be used safely, ECT can even be a first-line intervention.
Once strictly an inpatient procedure, today ECT is often performed on an outpatient basis. The treatment consists of a series of sessions, typically two-three times a week, for three to six weeks (usually 6-12 treatment sessions).
ECT may cause some side effects, including confusion, disorientation, and memory loss. Usually these side effects are short-term, but sometimes memory problems can linger, especially for the months around the time of the treatment course.
Advances in ECT devices and methods have made modern ECT safe and effective for most patients.
ECT is not painful, and you cannot feel the electrical impulses. Before ECT begins, a patient is put under brief anesthesia and given a muscle relaxant. Within one hour after the treatment session, which takes only a few minutes, the patient is awake and alert.
After ECT, you are most likely to continue on an antidepressant medication to prevent a recurrence of depression. For some patients who respond well to ECT who haven’t found any medications that work effectively, ongoing less frequent treatments – maintenance ECT therapy – may be an option.
Repetitive transcranial magnetic stimulation (rTMS) uses a magnet to activate the brain. First developed in 1985, rTMS has been studied as a treatment for depression, psychosis, anxiety, and other disorders. Unlike ECT, in which electrical stimulation is more generalized, rTMS can be targeted to a specific site in the brain. Scientists believe that focusing on a specific site in the brain reduces the chance for the types of side effects associated with ECT. But opinions vary as to what site is best.
As a treatment, rTMS is typically reserved for major depression in patients who do not respond to at least one antidepressant medication. It is also used in other countries as a treatment for depression in patients who have not responded to medications and who might otherwise be considered for ECT. It doesn’t require anesthesia like ECT. The procedure tends to be well tolerated; the most common side effects include some discomfort at the site of the procedure and in the muscles of the jaw or mild headaches.
Additional information about follow-up, questions to ask your health care provider, and more.
People with major depression are monitored for any suicidal thinking before and during treatment.
People with major depression should have a follow-up appointment with their health care provider at least every 2 weeks for at least 6 weeks or until treatment adherence and response have been achieved. After this, they have a follow-up appointment at least every 4 weeks until they enter remission (absence of depressive symptoms).
Download this worksheet from the National Institute on Aging.
If someone you know has depression, help them see a health care provider or mental health professional. You also can:
Take comments about suicide seriously, and report them to your loved one’s health care provider or therapist. If they are in immediate distress or thinking about hurting themselves, call 911 for emergency services or go to the nearest hospital emergency room.
Putting it all together.
This page was developed by the Division of e-Learning Innovation team and Dr. Anthony J. Levinson, MD, FRCPC (Psychiatry). Dr. Levinson is a psychiatrist and professor in the Department of Psychiatry and Behaviour Neurosciences, Faculty of Health Sciences, McMaster University. He is the Director of the Division of e-Learning Innovation, as well as the John Evans Chair in Health Sciences Educational Research at McMaster. He practices Consultation-Liaison Psychiatry (psychiatry of the medically ill), with a special focus on dementia and neuropsychiatry. He is also the co-developer of the iGeriCare.ca dementia care partner resource, and one of the co-leads for the McMaster Optimal Aging Portal. He and his team are passionate about developing high-quality digital content to improve people's understanding about health. By the way, no computer-generated content was used on this page. Specifically, a real human (me) wrote and edited this page without the help of generative AI like ChatGPT or Bing's new AI or otherwise.
Initially published in February 2023. Last reviewed February 28, 2023.
Dr. Levinson receives funding from McMaster University as part of his research chair. He has also received several grants for his work, from not-for-profit granting agencies. He has no conflicts of interest with respect to the pharmaceutical industry; and there were no funds from industry used in the development of this website.
Content was written and adapted based on credible, high-quality, non-biased sources such as MedlinePlus, the National Institutes for Mental Health, the McMaster Optimal Aging Portal, the American Psychiatric Association, the Cochrane Library, the Centre for Addictions and Mental Health (CAMH), Canadian Network for Mood and Anxiety Treatments (CANMAT), Health Quality Ontario Quality Standard, and others. See References below for additional details.
Funding was provided by the Labarge Optimal Aging Initiative and in-kind contributions from McMaster University and CAMH. There was no industry funding for this content.
Helpful Links and Resources
Expert-selected websites and documents related to depression.
Patient and Family Guide to Depression Treatment
Based on the CANMAT 2016 Clinical Guidelines, this PDF provides an overview of treatment options.View Resource
Health Quality Ontario Patient Reference Guide
HQO Quality Standard patient reference guide for major depression.View Resource
Mood Disorders Society of Canada
Links to National, Provincial, and Territorial Organizations.View Resource
Find Canadian Mental Health Association
Find CMHA in your area.View Resource
BounceBack is a free program from the CMHA that helps you build skills to improve your mental health.View Resource
Learn about types of anxiety, treatments, and what questions you should ask your healthcare provider.Anxiety
Review the causes of mild cognitive impairment, its diagnosis, and management.Cognitive Impairment
Subscribe to our weekly emails to learn more about other mental health topics like mild cognitive impairment and how to promote brain health. Find out about our live online events and know when new content is added to the site. You can opt out at any time.Subscribe
Evidence-based references that informed this topic.
About this Topic
This content was developed by the Division of e-Learning Innovation in the Faculty of Health Sciences, McMaster University. It was authored, reviewed, and assessed for accuracy by psychiatrist Dr. Anthony J. Levinson from McMaster. There are no conflicts of interest.
The development process included a review of the Canadian Network for Mood and Anxiety Treatments (CANMAT) Guidelines for depression; the American Psychiatric Association Clinical Practice Guideline on Depression; and Health Quality Ontario’s Quality Standard and Patient Guide on Major Depression.
If you have questions or comments related to this resource, please contact us at email@example.com.