What is Depression?

  • Feelings of sadness, despair, anxiety, emptiness, discouragement, or hopelessness; having no feelings; or appearing tearful.
  • A depressed mood may be a normal and, at times, adaptive response to loss, disappointment, or perceived failure.
  • A depressed mood may be a symptom of a medical condition like a concussion, iron deficiency anemia, hypothyroidism, low vitamin B12, etc.

Depression is a clinical diagnosis. There is no blood test or MRI that can diagnose it.

The health care practitioner must consider all possible physical and psychological conditions before reaching a diagnosis. Not all cases of a depressed mood are best explained by clinical depression. The task is to best put a name to a patient’s situation. Obviously, there is a lot in a name and you don’t want to give it the wrong name. But, there is also a lot not represented by the name and so the details that come out in the clinical consultation are even more important. Some common areas that need to be evaluated are:

  • how the problem started and possible triggering situations;
  • the nature of the patient’s symptoms and their consequences;
    • possibly using standardized, validated questionnaires
  • psychological susceptibilities for depression (including family history);
  • things in the patient’s life that aren’t helping matters (e.g., financial stresses, unideal living situation, relationship troubles, occupational stress, unbalance lifestyle, etc.);
  • possible medical conditions that can also create symptoms of depression;
    • possibly blood work or other investigations to identify these
  • risk for suicide

There are many different depressive disorders and many different subtypes of depression, all of which are important to appreciate when reaching a diagnosis and designing a treatment plan. However, generally, depression will have the following features at its core:


A. At least two weeks straight of 5 of the following:

  • Depressed mood most of the day, nearly every day.


  • Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day


  • Significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day***
  • Insomnia or sleeping too much nearly every day***
  • Being fidgety or restless, or just being very slowed down and not doing much
  • Fatigue or loss of energy nearly every day***
  • Feelings of worthlessness or excessive or inappropriate guilt nearly every day
  • Difficulty with concentration, nearly every day***
  • Recurrent thoughts of death

B. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.***
C. The episode is not attributable to the direct physiological effects of a substance or to another medical condition.***


***Aren’t a lot of these symptoms also caused by Post-Concussion Syndrome (PCS)?

Yes, these can be due to the physiological changes associated with post-concussion syndrome and so would not be counted towards this diagnosis. However, it’s still useful to identify a depressed mood when it’s there because depression can happen with PCS and depression treatment approaches are usually equally helpful and appropriate in the PCS context.

Judging by the diagnostic criteria above, one may think that diagnosing depression and formulating a treatment plan is pretty straightforward. However, there are many different depressive disorders and many different subtypes all of which are important to appreciate when reaching a diagnosis and designing a treatment plan. And then again, that’s assuming it is depression. Perhaps the patient’s situation better matches with another physical or psychological condition and the treatment plan can be most efficiently treated in another way.

For example, a patients with chronic sinusitis or iron deficiency anemia can present with symptoms of depression and even satisfy the diagnostic criteria. But, the most efficient treatment would be to treat the chronic sinusitis or iron deficiency anemia, possibly in addition to other depression-oriented evaluations/treatments. Treating these conditions purely as depression may leave patients and health care practitioners feeling unsatisfied.

What is the state of depression in today's day and age?


  • A survey of more than 78,000 parents in the United States in 2007 found that among their children, at that specific time, instances of depression could be reported as follows (Perou et al., 2013):
    • 3 to 5 years – 0.5 percent
    • 6 to 11 years – 1.4 percent
    • 12 to 17 years – 3.5 percent
  • The one year and lifetime prevalence rates of depression are even higher. For example, a study found that the lifetime prevalence in adolescents was 11 percent (Avenavoli et al., 2015).

Risk factors for onset of pediatric depression (Bonin, 2019)

  • Low birth weight
  • Family history of depression and anxiety in first-degree relatives (including antenatal or postpartum maternal depression)
  • Family dysfunction or caregiver-child conflict
  • Exposure to early adversity (eg, abuse, neglect, or early loss)
  • Psychosocial stressors (eg, peer problems and victimization [bullying], and academic difficulties)
  • Gender dysphoria and homosexuality, especially if youth is bullied
  • Negative style of interpreting events and coping with stress
  • History of anxiety disorders, substance use disorder, learning disabilities, attention deficit hyperactivity disorder, and oppositional defiant disorder
  • Traumatic brain injury
  • Chronic illness, especially if symptom and/or treatment burden yields chronic life disruptions

Lifetime prevalence

Nationally or regionally representative community surveys in 14 countries found that the estimated lifetime prevalence of  major depression and persistent depressive disorder (dysthymia) in adults was 12 percent (Kessler et al., 2011).

  • Developed countries (United States and Europe) – it was approximately 18 percent.
  • Developing countries (e.g., Peoples’ Republic of China, Mexico, and Brazil) – it was approximately 9 percent.

Why is the prevalence of depression about double in the developed world vs. the developing world?

Researches think it is due to cultural, genetic and statistical factors (Weissman et al., 1996; Gureje et al., 2007).


Twelve-month prevalence

In the United States, the chance of an adult to have major depression and persistent depressive disorder is approximately 6 and 2 percent, respectively (Karg et al., 2015)

The 2019 World Happiness Report evaluated happiness in different countries by asking people to answer a survey about their satisfaction with their lives (Cantril ladder questions). Then, researches created a model that would help explain the differences in overall happiness between countries. The model looks at the following categories as the main determinants of happiness:

  1. GDP per capita [Dark Purple]
  2. Healthy life expectancy at birth [Fuschia]
  3. Social support; “If you were in trouble, do you have relatives or friends you can count on to help you whenever you need them, or not?” [Orange]
  4. Freedom to make life choices; “Are you satisfied or dissatisfied with your freedom to choose what you do with your life?” [Yellow]
  5. Generosity; “Have you donated money to a charity in the past month?” on GDP per capita [Aqua]
  6. Perceptions of corruption; “Is corruption widespread throughout the government or not?” and “Is corruption widespread within businesses or not?” [Dark Mauve]
  7. The part of happiness not explained by the above 6 categories [Light Mauve]

Here are the results:

Depression seems to be more common in females

In two separate meta-analyses including nationally representative samples with over 1.7 million people each (a large number of participants!), researchers found that females were 1.95 times more likely to have major depression than males. They found that depression symptoms and diagnoses peaks in adolescence at 12-year-old when females are 2.37 times more likely than 12-year-old males to have clinical depression than males. The gender gap then narrows and remains stable in adulthood (Salk et al., 2017). Statistics Canada had similar findings.


Theories as to why this is

It’s important to state that more studies are needed here but researches have a few theories to explain the findings above.

  1. Higher levels of negative cognitive style in girls than boys beginning in early adolescence;
  2. Higher levels of stress for girls than boys beginning in early adolescence (Hyde et al., 2008b; Cole et al., 2008).
  3. Early puberty is disadvantageous for girls but not boys, for outcomes such as depression (Ge, Conger, & Elder, 2001), perhaps due to:
    • early puberty girls encountering more peer sexual harassment than boys and on-time girls (Lindberg, Grabe, & Hyde, 2007).

One way to think about mood

1. Maladaptive. Here, the emotions are deviant and not helpful at all. They can be seen as neurotic.

E.g., George Constanza from Seinfeld, Episode “The Pilot” (1993).

George Costanza: What if the pilot gets picked up, and it becomes a series?
Dana Foley: That would be wonderful, George. You’ll be rich and successful.

George Costanza: Yeah, that’s exactly what I’m worried about. God would never let me be successful. He’d kill me first. He’d never let me be happy.
Dana Foley: I thought you didn’t believe in God.

George Costanza: I do for the bad things.
Dana Foley: Do you hear what you’re saying? God isn’t out to get you, George. What… What is that on your lip?

George Costanza: What?
Dana Foley: It’s like a discoloration. It’s white.

George Costanza: [looks in a mirror]  Yes. Yes, it’s white. Why is it white?
Dana Foley: You’d better get that checked out.

George Costanza: “Better get that checked out”?
Dana Foley: I would.

George Costanza: What kind of a therapist are you? I’m telling you I’m scared that something terrible is gonna happen to me. Right away you start looking for tumors?
Dana Foley: I’m trying to help.

George Costanza: What are you, like a sadist? No matter how bad somebody feels, you can make ’em feel worse? I’ll bet you’re rootin’ for the tumor!

Dana Foley: I think you’d better go.
George Costanza: Well, I’m going, baby! I’m goin’!


2. Adaptive. Here, the emotions are a messenger, like a carbon monoxide detector sounding. Although it’s unpleasant, it’s beneficial. Will you check in and hear what it’s trying to tell you?

E.g., A patient of the clinic once was getting extreme anxiety while driving. His history and physical exam showed a pattern of deficits that localized the majority of his problems to his right parietal lobe.

Doctor: Might your anxiety be trying to tell you something?
Patient: I don’t think so, I just feel like I’m losing control

Doctor: Were you aware that patients with parietal lobe deficits are more prone to car accidents?
Patient: No I didn’t.

Doctor: Isn’t that amazing, but your body seemed to intuitively know.
Patient: Perhaps it’s just telling me to be careful and I’m misinterpreting it (the emotions) as attacking me.


Within a week, this patient accepted his anxiety as a messenger telling him to be careful and he saw it as such. His anxiety phased out by week 2 afterthis conversation. By week 6 after this conversation, he was asking us as to whether he could go on a 10 hour road trip (to which we said no, but for other reasons related to visual-vesitublar mismatch).


3. Instrumental. You use your emotions as a tool to get what you want.

E.g., From the movie “Training Day”, Ethan Hawke says to Denzel Washington’s character…

“It’s all about smiles and cries. Yeah. You gotta control your smiles and cries, because that’s all you have and nobody can take that away from you.”

E.g., Like you crying to get out of a speeding ticket.

Imagine 3-year-old you. Imagine that all your mom does is make you:

  • clean up the house
  • potty train
  • eat liver
  • do learning assignments
  • give you time outs
  • and puts you to bed

This all adds up to a pretty grumpy child.


What’s missing? Where is all the fun? Where are the rewards? Where is the incentive for trying or the hope for a happy day?

This may sound like a pretty improbable example as really, who treats a 3-year-old like that? But, how many of us treat ourselves with the same callousness…I have to tell you, many!


Where is the other side of this formula? These are all withdrawals from the happiness account…Where are the deposits?

Basically, influential studies have shown that depressed people don’t make enough effort in doing fun things (Lewinsohn, 1974).

Check out our article on Therapeutic Activities, but by all means, the list there is not exhaustive.


Been there, done that? It’s not as fun as it used to be?

Guess what, studies show that we tend to underestimate the joy derived from repeating activities we have already done (O’Brien, 2019).

If you would like to test out if this is true, why don’t you keep track using the Pleasure Predicting Log?

Basically, if it was fun before, do it again.


A more balanced formula

Adds to happiness: going to the spa, having a healthy meal, intimacy with partner, warm conversation with mother, making a tie dye shirts for Christmas gifts, telling yourself you look good, a nice meal with friends, etc.

Chores that adults often have to do to make us long for a reward: dealing with a demanding boss, cleaning out the gutters, having to let an employee go, having to discipline a child, phoning your phone company to argue a billing error, being a shoulder to cry on (again) for your chronically down high school friend, etc.

Medication vs. Psychotherapy

Initial treatment of mild to moderate major depression with antidepressant medications leads to response or remission in roughly 50 to 60 percent of patients (Gartlehner et al., 2011; Papakostas et al., 2008).


  • An inability to identify and describe emotions that you feel or observe in others.
  • It an also be described as difficulty with being socially aware and how you fit into you social environment.
  • Some people describe it as feeling numb, not being able to feel and/or existential angst.
  • Some people are just like that and so it can be considered a personality trait.
  • It can be associated with illnesses.
  • It can be associated with the use of antidepressants.


What is the link between antidepressant use and alexithymia?

In a study involving 1829 adults evaluating for adverse effects of antidepressant medications (Read et al., 2014), the most frequently reported adverse effects were:

  • Sexual Difficulties (62%)
  • Feeling Emotionally Numb (60%)
  • Feeling Not Like Myself (52%)
  • Reduction In Positive Feelings (42%)
  • Caring Less About Others (39%)
  • Suicidality (39%)
  • Withdrawal Effects (55%)


So for some people, antidepressants, although they may help reduce depression they don’t improve mood?

  • That seems to be the case for many patients. In these patients, antidepressants can help remove the weeds from the mood garden, but they don’t plant any flowers.
  • Perhaps a depressed mood is a message of some change you need to make in your lifestyle or the way you think about things?
  • If you had a knee pain, would you simply take analgesics to quieten the pain? Or, would you try to figure out what’s going on and fix the root problem?

CBT has been shown to be an effective treatment for depression. Studies suggest that it comparable in efficacy and offers some advantages over medication.

  • A Meta-analysis (pooled results from 115 studies) concluded that there is no doubt that CBT is an effective treatment for adult depression (Cuipers et al., 2013).
  • A study of 104 patients showed that CBT provided enduring results that lasted longer than the treatment period where as the benefits of medications have a higher chance of wearing off after the medication is discontinued. In the group of patients treated with CBT, only 31% relapsed at 1 year follow-up whereas 76% in the medication group relapsed one year after stopping the medication (Hollon et al., 2005).
  • In a study of 327 twelve to seventeen year-old patients, adding CBT to medication accelerated treatment response and reduced the incidence of suicidal events (14.7% vs 8.4%) (Posner et al., 2007).
  • A study of 212 twelve to eighteen year-old patients who refused antidepressant medications for their depression showed that they did better with CBT and that CBT may reduce the risk of future recurrent depression episodes (Clarke et al., 2016).


A 2018 study found that about 50% of people who suffer an episode of depression don’t have another one and return to high functioning levels (Rottenberg et al., 2018).

Wouldn’t you want to know at the outset that you have a 50% chance that depression will go away and won’t come back again in your lifetime?

Avenevoli, Shelli & Swendsen, Joel & He, Jian-Ping & Burstein, Marcy & Merikangas, Kathleen. (2014). Major Depression in the National Comorbidity Survey- Adolescent Supplement: Prevalence, Correlates, and Treatment. Journal of the American Academy of Child & Adolescent Psychiatry. 54. 10.1016/j.jaac.2014.10.010.

Bonin, Liza. (2019). Pediatric unipolar depression: Epidemiology, clinical features, assessment, and diagnosis. UpToDate.

Clarke, G., DeBar, L. L., Pearson, J. A., Dickerson, J. F., Lynch, F. L., Gullion, C. M., Leo, M. C., (May 2016). Cognitive Behavioral Therapy in Primary Care for Youth Declining Antidepressants: A Randomized Trial. Pediatrics, VOLUME 137 / ISSUE 5.

Cole, D. A., Ciesla, J. A., Dallaire, D. H., Jacquez, F. M., Pineda, A. Q., Lagrange, B.,… Felton, J. W. (2008). Emergence of attributional style and its relation to depressive symptoms. Journal of Abnormal Psychology, 117, 16 –31.

Cuijpers, Pim & Berking, Matthias & Andersson, Gerhard & Quigley, Leanne & Kleiboer, Annet & Dobson, Keith. (2013). A Meta-Analysis of Cognitive-Behavioural Therapy for Adult Depression, Alone and in Comparison With Other Treatments. Canadian journal of psychiatry. Revue canadienne de psychiatrie. 58. 376-85. 10.1177/070674371305800702.
Gartlehner G, Hansen RA, Morgan LC, et al. (2011) Comparative benefits and harms of second-generation antidepressants for treating
major depressive disorder an updated meta-analysis. Ann Intern Med 155: 772–785.

Ge, X., Conger, R. D., & Elder, G. H., Jr. (2001). Pubertal transition, stressful life events, and the emergence of gender differences in adolescent depressive symptoms. Developmental Psychology, 37, 404 – 417.

Gureje, O., Kola, L. & Afolabi, E. Epidemiology of major depressive disorder in elderly Nigerians in the Ibadan Study of Ageing: a community-based survey. Lancet 370, 957–964 (2007)

Hollon, Steven & DeRubeis, Robert & Shelton, Richard & Amsterdam, Jay & Salomon, Ronald & O’Reardon, John & Lovett, Margaret & Young, Paula & Haman, Kirsten & Freeman, Brent & Gallop, Robert. (2005). Prevention of Relapse Following Cognitive Therapy vs Medications in Moderate to Severe Depression. Archives of general psychiatry. 62. 417-22. 10.1001/archpsyc.62.4.417.

Hyde, J. S., Mezulis, A. H., & Abramson, L. Y. (2008b). The ABCs of depression: Integrating affective, biological, and cognitive models to explain the emergence of the gender difference in depression. Psychological Review, 115, 291–313.

Karg RS, Bose J, Batts KR, et al. Past Year Mental Disorders among Adults in the United States: Results from the 2008–2012 Mental Health Surveillance Study. Substance Abuse and Mental Health Services Administration, Center for Behavioral Health Statistics and Quality Data Review. October, 2014 (Accessed on January 16, 2015).

Kessler, Ronald & Ormel, Johan & Petukhova, Maria & Mclaughlin, Katie & Green, Jennifer & Russo, Leo & Stein, Dan & Zaslavsky, Alan & Aguilar-Gaxiola, Sergio & Alonso, Jordi & Andrade, Laura Helena & Benjet, Corina & de Girolamo, Giovanni & Graaf, Ron & Demyttenaere, Koen & Fayyad, J. & Haro, Josep Maria & Hu, C.Y. & Karam, A. & Ustun, Tevfik. (2011). Development of Lifetime Comorbidity in the World Health Organization World Mental Health Surveys. Archives of General Psychiatry. 68. 90-100.

Kessler, Ronald & Berglund, Patricia & Demler, Olga & Jin, Robert & Merikangas, Kathleen & Walters, Ellen. (2005). Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV Disorders in the National Comorbidity Survey Replication. Archives of general psychiatry. 62. 593-602. 10.1001/archpsyc.62.6.593.

Lewinsohn, P. M. (1974). A behavioural approach to depression. In R. J. Freedman, & M. Katz (Eds.), The psychology of depression (pp. 157-174). Oxford: Wiley.

Lindberg, S. M., Grabe, S., & Hyde, J. S. (2007). Gender, pubertal development, and peer sexual harassment predict objectified body consciousness in early adolescence. Journal of Research on Adolescence, 17, 723–742.

O’Brien, E. (2019). Enjoy it again: Repeat experiences are less repetitive than people think. Journal of Personality and Social Psychology, 116(4), 519-540.

Papakostas, George & Fava, Maurizio. (2008). Does the probability of receiving placebo influence clinical trial outcome? A meta-regression of double-blind, randomized clinical trials in MDD. European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology. 19. 34-40. 10.1016/j.euroneuro.2008.08.009.

Perou  R, Bitsko  RH, Blumberg  SJ,  et al; Centers for Disease Control and Prevention (CDC).  Mental health surveillance among children: United States, 2005-2011.  MMWR Surveill Summ. 2013;62(suppl 2):1-35.

Posner, Kelly & March, John & Silva, Susan & Petrycki, Stephen & Curry, John & Wells, Karen & Fairbank, John & Burns, Barbara & Domino, Marisa & McNulty, Steven & Vitiello, Benedetto & Severe, Joanne & Casat, Charles & Kolker, Jeanette & Riedal, Karyn & Feeny, Norah & Findling, Robert & Stull, Sheridan & Baab, Susan & Rochon, James. (2007). The Treatment for Adolescents With Depression Study (TADS): Long-term Effectiveness and Safety Outcomes. Archives of General Psychiatry. 4. 1132-1144.

Read, John & Cartwright, Claire & Gibson, Kerry. (2014). Adverse emotional and interpersonal effects reported by 1,829 New Zealanders while taking antidepressants. Psychiatry Research. 216. 10.1016/j.psychres.2014.01.042.

Rottenberg, Jonathan & Devendorf, Andrew & Kashdan, Todd & Disabato, David. (2018). The Curious Neglect of High Functioning After Psychopathology: The Case of Depression. Perspectives on Psychological Science. 13. 549-566. 10.1177/1745691618769868.

Salk, Rachel & Hyde, Janet & Abramson, Lyn. (2017). Gender Differences in Depression in Representative National Samples: Meta-Analyses of Diagnoses and Symptoms. Psychological Bulletin. 143. 10.1037/bul0000102.

Statistics Canada.  Table  13-10-0703-01   Probability of depression, by sex, household population aged 12 and over, Canada, provinces and territories

Weissman, Myrna & Bland, Roger & Canino, Glorisa & Faravelli, Carlo & Greenwald, Steven & Hwu, Hai-Gwo & Joyce, Peter & Karam, Elie & Lee, C.K. & Lellouch, Joseph & Lépine, Jean-Pierre & Newman, Stephen & Rubio-Stipec, Maritza & Wells, Jessie & Wickramaratne, Priya & Wittchen, Hans-Ulrich & Yeh, E.K.. (1996). Cross-National Epidemiology of Major Depression and Bipolar Disorder. JAMA : the journal of the American Medical Association. 276. 293-9. 10.1001/jama.1996.03540040037030.

Last update: October 2019