Depression: Symptoms, Test, Causes, Treatment

About one in five people will suffer from depression during their life. [1, 2] It is the leading cause of disease burden in North America.[3]  In this page you will learn the causes, symptoms, and treatment of depression. Read how you can overcome depression and change your life.

Table of Contents

  1. Symptoms of Depression
  2. Definition and Diagnosis
  3. Depression Tests
  4. Causes of Depression
  5. Grief and Loss
  6. Medications that Can Cause Depression
  7. Treatment of Depression
  8. Family Support
  9. Links and Find Help

Eight Symptoms of Depression

  • Depressed mood: Sad, hopeless, empty, teary
  • Loss of interest: No enjoyment, don’t care, socially withdrawn
  • Low energy: Tired, physically drained
  • Anxious or irritable: Restless, worried, can’t turn off your mind, frustrated
  • Poor concentration: Hard to think, concentrate, make decisions
  • Sleep changes. Difficulty falling asleep or staying asleep, need more sleep, don’t feel refreshed in the morning
  • Appetite or weight changes: Appetite lower or higher, no pleasure in eating
  • Thoughts of death: Recurrent thoughts of death, suicide, or not existing

Depression affects your body and mind. It is more than just sadness.

Definition and Diagnosis of Depression (DSM-F32.0, F33.0)

Depression disorder diagnostic criteria based on the DSM-5.[4]

  • Is your mood depressed, or you have significantly lost interest or enjoyment? Plus at least 4 of the following symptoms:
    • Low energy. Is your energy lower? Do you feel more fatigued or sluggish? Is it hard to get going in the morning? Do you have less interest in sex?
    • Anxiety or irritability. Are you more anxious, worried, fearful, irritable, or intolerant?
    • Lower self-confidence. Is your self-confidence or self-esteem lower? Do you feel more hopeless or pessimistic, or do you feel more guilty or worthless?
    • Poor concentration. Is it hard for you to think, concentrate, or make decisions? Do you find it hard to concentrate outside of work? Is it harder to read articles or to take in what you read?
    • Sleep changes. Do you have difficulty falling asleep or staying asleep? On weekends do you feel like you could sleep all day? Do you feel that you're not refreshed when you wake up in the morning?
    • Appetite or weight change. Is your appetite either significantly lower or higher than a year ago. Have you unintentionally lost or gained weight? Do you eat only because you have to eat, but get little pleasure from food?
    • Slow moving or restless. Do you move more slowly? Is your speech slower. Are you restless or fidgety?
    • Thoughts of death. Do you think it would be easier if you just didn't wake up in the morning? Do you think it would be easier if you developed a serious illness? Do you think that your family would be better off if you were gone? Do you have recurrent thoughts of death or suicide (not just a fear of dying)? Do you imagine ways of hurting yourself?
    • Have your symptoms lasted for at least two weeks?
    • Have your symptoms had a significant negative impact on your life (relationships, work, social life, or emotional life)?
    • Your symptoms are not due to medication, substance abuse, or any other medical condition (e.g., hypothyroidism).
    • Your symptoms are not due to another mental health condition such as anxiety or bipolar disorder.

    Related Conditions

    Major depressive disorder replaces previous names of clinical depression, major depression, and depression. They all mean the same thing. They were different names given to the same condition. Below are variations of major depressive disorder that apply to specific situations.

    Persistent depressive disorder (dysthymia) is depression that last for at least 2 years. The symptoms tend to be milder than those for major depressive disorder (depression). A person with persistent depressive disorder may have episodes of major depression along with periods of milder symptoms. Approximately 15 percent of people who have depression, have persistent depressive disorder.[5]

    Seasonal affective disorder (SAD) is depression but typically occurs from late fall to spring. A small percent of people suffer from SAD during the summer instead of the winter. Individuals with SAD can be just as depressed as individuals with major depression.

    Perinatal depression is depression that occurs either during pregnancy or after delivery (postpartum depression). Women are often reluctant or embarrassed to admit that they feel depressed after a baby’s birth, which is supposed to be a joyous event. But it is important to call your doctor and ask for help.

    Premenstrual dysphoric disorder can have the same symptoms as major depression but is associated with hormone changes. The symptoms typically begin days before the start of a menstrual period and begin to improve within a few days after onset of the period.

    Anxiety often coexists with depression. Some doctors feel if a patient suffers from anxiety, the first cause that should be considered is depression because they are so closely correlated.[6] (Learn more about anxiety…)

    • 72 percent of individuals with anxiety will also have depression.
    • 48 percent of individuals with depression will also have anxiety.
    • Anxiety begins before or concurrently with depression in 37 percent of people.
    • Depression begins before or concurrently with anxiety in 32 percent of people.

    Bipolar Disorder

    Bipolar disorder is periods of alternating high and low moods that are significant enough to have a negative impact on an individual’s life. Bipolar disorder is often misdiagnosed as depression because patients rarely mention elevated moods and only focus on depressed moods. In fact, the average time between onset of bipolar symptoms and a formal diagnosis is almost eight years.[7] (Learn more about bipolar disorder…)

    Depression Tests

    Medical Tests

    There is no simple blood test for depression. The diagnosis of depression is based on history. Depression is caused by changes in neurotransmitters in the brain, and a blood test cannot check what is happening inside the brain. The blood-brain barrier separates blood in the body from the brain and the central nervous system.

    Your health care provider can determine if your depression is caused by an underlying medical condition, such as heart disease or thyroid problems. This may require blood tests and an electrocardiogram (ECG). A complete assessment should also include questions about your alcohol consumption and any substance use, which can contribute to depression.

    Tests for Major Depressive Disorder (MDD) and Bipolar Disorder

    Tests for depression and bipolar disorder based on the DSM criteria:
    Major Depression Test – DSM Criteria (pdf)
    Bipolar Disorder Test – DSM Criteria (pdf)

    Screening test for identifying depression:
    The Patient Health Questionnaire (PHQ-9) It has been proven to be effective for the diagnosis of major depressive disorder. [8, 9]
    Online version of the Patient Health Questionnaire - PHQ9 test (pdf).

    Developing a screening test for major depressive disorder in children and adolescents has proven to be difficult. A review of 20 screening tests for children and adolescents concluded that none of the tests could accurately assess depression, and that reliance on the tests alone would result in the overdiagnosis of depression.[10]

    How Depression Feels

    The best one-line description of depression is that it feels like lack of vitality.

    You don't have to feel sad to be depressed. This is a common misunderstanding. People often think they're not depressed, because they're not sad. But sadness is not a necessary symptom of depression. People often manifest their depression in other ways. Depression affects your entire body. Everything slows down. You have low energy and lack of enjoyment.

    Most individuals who suffer from depression also feel irritable and intolerant. When patients begin to pull out of depression, they usually say that they begin to feel more tolerant, and that family and friends don’t irritate them as much.

    It’s only people who haven’t suffered from depression who think it isn’t real. They are usually full of well-meaning advice that’s not very helpful. They will tell you things such as, “You just have to pull up your socks, or go out more.” But if you’ve suffered from depression, you know it’s not that simple.

    Thoughts of Hurting Yourself and Suicide

    Thoughts of hurting yourself are frightening but a common part of depression. Suicidal thoughts are the most frightening aspect of depression. Therefore, it's important to discuss them openly. Most people who are depressed will have at least some thoughts of dying, hurting themselves, or not existing.

    There is a difference between active and passive thoughts of self-harm. In passive thoughts, you think that it would be easier if you weren't alive, if you developed a fatal disease, or if you went to sleep and didn't wake up. But you don't want to hurt yourself. In active thoughts of self-harm, you think about hurting yourself. Both are serious, but active thoughts of self-harm are obviously more serious.

    Passive thoughts of hurting yourself are usually fleeting. It's easy to chase them away by remembering that you want to get better, that suicide is permanent, and that it would hurt the people left behind. It can be comforting to know that there is a big difference between having thoughts of hurting yourself and acting on them.

    If you have thoughts of hurting yourself, you should immediately discuss them with your health professional. If your thoughts of death or hurting yourself change in character, if they occur more often, if it's harder to chase them away, or if you start to make plans of how to hurt yourself, seek help immediately. Contact your health professional, call a crisis hotline, or go to emergency.

    Levels of Depression

    There are different levels of depression. Most people automatically assume the worst when they hear depression. They think that they'll become bedridden or suicidal. But that's the most severe level of depression. It's more common to have mild depression, where you can still go to work and function – it's just that your energy and sense of enjoyment are low.

    Depression usually doesn't get worse. If you have mild depression, it is unlikely that it will get worse and turn into severe depression. Not that that's much consolation, since even mild depression is painful. But it should give you a little comfort to know that your symptoms probably won't get worse.

    Recurrence Rates of Depression

    After one episode of depression, the risk of another episode is 50 percent.
    After two episodes of depression, the risk of another episode is 70 percent.
    After three episodes of depression, the risk of another episode is 90 percent.[11]

    If the underlying cause of depression is not treated, depression is likely to recur. For example, substance abuse is an important cause of depression. If substance abuse is not treated, the risk of another episode of depression is high.

    Causes of Depression

    There are six basic causes of depression:

    • Negative thinking
    • Grief and loss
    • Drug or alcohol abuse
    • Chronic pain
    • A family history of depression
    • Medical conditions

    Here is a deeper look at each one.

    Negative Thinking

    Feeling Trapped

    In most cases, depression is due to feeling trapped in your life. If you feel trapped, you'll struggle against that feeling until you eventually become exhausted and depressed. You can feel trapped by external factors, such as a job that you don’t like or an unhealthy relationship that won’t change. But in many cases, you are trapped by your own thinking, such as poor self-esteem or negative self-labeling. Here are some examples of how negative thinking can lead to feeling trapped.

    How Negative Thinking Causes Depression

    Negative self-labeling can lead to depression. If you think that you’re flawed or inadequate, you’re also saying that you don’t have the ability to be happy. Even worse, you may think that you don’t deserve to be happy. Self-labeling creates a vicious cycle that makes you feel more trapped. If you behave as if you’re flawed, or take on the “poor me” role, people will respond to you that way. They’ll be dismissive, and your negative self-labeling will become self-fulfilling.

    Focusing on the negatives, or disqualifying the positives makes you feel trapped. When you disqualify the positives, you focus on your failures and don’t appreciate your successes. You find it hard to accept compliments. “If you knew the real me, you wouldn’t like me.” Focusing on the negatives makes you feel trapped, because it makes it hard to change. When a friend or a counsellor asks you to list your strengths, you can’t think of any. It’s hard to challenge your negative view of yourself, therefore you remain stuck.

    Being a people-pleaser can lead to depression. If you’re a people-pleaser, you put everybody’s happiness before your own. People may admire your selflessness, and in the beginning, you may enjoy that approval. But eventually you feel trapped.

    You’re trapped by everyone’s expectations. If you take time for yourself, you feel selfish. If you try to slow down, you risk disappointing others. What began as a pleasure becomes a burden.

    The Difference Between Sadness and Depression

    Sadness is an appropriate response to a negative event. The difference between sadness and depression is that sadness is not burdened with negative thinking. If you lose your job, it's normal to feel sad. But if you think that losing your job means that you're a failure, or that you have missed your one chance at success, then you'll feel depressed.

    Because sadness is appropriate, it is temporary. When you're sad, you can do things to pick up your spirits. You can talk to friends or distract yourself. But depression usually doesn't get better unless you change your negative thinking.

    Grief and Loss

    Grief is a natural response to the loss of someone or something close to you. It does not have to lead to depression, but it can if it is not handled properly.

    Main Causes of Grief and Loss

    • Death of a loved one
    • Physical or emotional trauma
    • Separation or divorce
    • Major illness
    • Loss of a job or income
    • Children leaving home
    • Death or loss of a pet
    • Retirement
    • Moving

    The Five Stages of Grief

    It’s important to remember that these five stages of grief are just an outline. Each person will experience grief in their own way. Some will skip steps, and others will go through them in a different order.[12]

    • Shock and Denial: Many people are briefly in a state of shock and don’t feel anything initially. Denial is a defense mechanism and lets you take in only as much as you can handle.
    • Pain and Anger: Loss causes pain, and pain can lead to anger. The anger can be directed at anyone, from the person who has passed on, to yourself, to your friends, or to God. It is an irrational anger born of pain.
    • Trying to Explain and Bargaining: This stage is often called bargaining, but it often takes the form of trying to explain what happened. “Maybe I should have done this…” “Why did that have to happen?” “What else could I have done?”
    • Sadness or Depression: As you begin to come to terms with your loss, it is natural to feel slightly empty and sad. Some or all of the symptoms of depression can come up here. It’s not unusual for people to withdraw during this phase.
    • Resolution and Acceptance: This stage is about accepting the reality of your loss. Realizing that it cannot be changed, and creating a new life so that you can move forward.

    Substance Abuse and Depression

    All drugs and alcohol are brain depressants. In moderate amounts, alcohol does not lead to depression, but drug or alcohol abuse, including opioid abuse, will definitely lead to depression. This is because they deplete your brain of neurotransmitters such as serotonin and dopamine. Brain scans have shown that it can take months for your brain chemistry to return to normal after drug or alcohol abuse.

    Alcohol abuse almost doubles the risk of depression.[13] One study looked at 2,945 alcoholics. Fifteen percent were depressed before they began abusing alcohol, and that number jumped to 26 percent after they started abusing alcohol. Once they stopped drinking for an extended period, 15 percent remained depressed. In other words, alcohol doubles the risk of depression. (Learn more about alcohol abuse, alcoholism and recovery…)

    Marijuana users are four times more likely to develop depression.[14] One study followed a large group of people for 16 years. It discovered that people who smoked marijuana were four times more likely to develop depression. This was confirmed by another large study of 1601 students.[15] (Learn more about marijuana abuse, addiction and recovery…)

    Even stimulants such as cocaine cause depression. Cocaine initially stimulates your brain, and temporarily elevates your mood. But over the long run it depletes your brain of neurotransmitters and leads to depression.

    Dual Diagnosis

    Approximately 15 to 30 percent of addicts suffer from both addiction and underlying depression.[13, 16] The combination of depression and addiction is sometimes called a dual diagnosis. People who have a dual diagnosis often have a repeating pattern of staying sober for a while and then relapsing because they feel awful.

    If you have a dual diagnosis and your depression isn't treated, you're more likely to relapse, because your recovery feels flat and unrewarding. If you're depressed for too long, you'll eventually think of turning to your addiction to escape. Individuals who don't have a dual diagnosis, generally start to feel better quickly after they stop using.

    Dual diagnosis is hard to diagnose in the first few months of recovery. It's hard to decide if the symptoms of depression are due to an underlying depression or due to the depressant effect of drugs and alcohol. You usually have to be abstinent for at least 3 months before a diagnosis of underlying depression can be made. Sometimes it takes as long as 6 months for your brain chemistry to begin to return to normal. Of course, these are only general guidelines.

    Chronic Pain

    Chronic pain is a well-known trigger for anxiety and depression. Factors that increase the risk of developing anxiety or depression are, a higher number of pain locations, joint pain, pain lasting more than three months, daily use of pain medication, and a higher level of pain.[17] Up to 50 percent of patients with chronic pain also suffer from an anxiety disorder.[18]

    A review of eighty-three studies tried to answer the question of whether chronic pain causes depression or if depression leads to chronic pain. The conclusion is that chronic pain causes depression.[19]

    Family History and Depression

    Genes explain approximately 30 to 40 percent of depression.[20, 21] Approximately 60 to70 percent of depression is due to environmental factors and poor coping skills. This has been proven by looking at identical twins, which have the same genes. Genes would explain 100 percent of depression if every time one twin developed depression the other twin also developed depression. But in fact, when one identical twin develops depression, the other twin develops depression approximately 30 to 40 percent of the time.

    Depression is caused by changes in neurotransmitters such as serotonin and dopamine. Your brain has to produce these neurotransmitters to keep your mood balanced. If you have a family history of depression, your brain has a harder time producing those neurotransmitters in the right quantities, which means you are predisposed to depression.

    If you think about it, it's a miracle that more people don't get depressed. Your brain has to produce millions of chemicals every day in exactly the right amounts in order to function properly. If it produces some of those chemicals in slightly reduced amounts, or not at exactly the right time, you will feel depressed.

    Families sometimes hide a history of depression, so it can be hard to recognize. Most people don't openly admit that they suffer from depression, and previous generations were reluctant to seek treatment for depression. Sometimes you have to decide if you have a family history of depression, not by what people say, but by how they behave. If your depression is mainly due to family history, it's more likely you may need antidepressants to overcome your depression.

    Medical Causes of Depression

    The majority of depression is due to negative thinking and/or substance abuse. But certain diseases and medications can also cause depression.

    Medical Conditions that Can Cause Depression

    • stroke or heart disease
    • cancer
    • endocrine disorders, such as diabetes, thyroid disease
    • degenerative neurological conditions, such as multiple sclerosis, Parkinson's disease, and Alzheimer's disease
    • immune system diseases, such as lupus
    • viruses, such as mononucleosis, hepatitis, and HIV
    • anemia, lack of vitamin B12
    • sexual and erectile dysfunction

    Your doctor may choose to do blood tests to rule out some medical causes of depression.

    Medications that Can Cause Depression

    One-third of adults take prescribed medications that may cause depression or increase the risk of suicide.[22, 23] Here is a partial list:

    • Antibiotics: Ciprofloxacin, Levofloxacin, Metronidazole, Moxifloxacin, Ofloxacin.
    • Anticonvulsants: Carbamazepine, Ethosuximide, Gabapentin, Lamotrigine, Levetiracetam, Lorazepam, Methsuximide, Oxcarbazepine, Phenytoin, Pregabalin, Topiramate, Valproic Acid, Zonisamide.
    • Antidepressants: For a small group of people, antidepressants can make depression worse, and for young adults under the age of 25, antidepressants can increase the risk of suicide. However, research shows that the risks outweigh the benefits.
    • Antihypertensives: Acebutolol, Atenolol, Betaxolol, Nadolol, Enalapril, Metoprolol, Propranolol, Quinapril, Telmisartan, Timolol, Trandolapril.
    • Corticosteroids: Betamethasone, Cortisone, Dexamethasone, Methylprednisolone, Prednisolone, Prednisone, Triamcinolone.
    • Gastrointestinal: Cimetidine, Dexlansoprazole, Esomeprazole, Famotidine, Metoclopramide, Omeprazole, Ranitidine.
    • Hormones: Conjugated Estrogens, Estradiol, Hydroxyprogesterone, Medroxtyprogesterone, Megestrol, Norethindrone, Tamoxifen, Testosterone.
    • Neurologic: Carbidopa, Levodopa, Rotigotine.
    • Opioids and pain: Cyclobenzaprine, Fentanyl, Hydrocodone, Hydropmorphone, Oxycodone, Tapentadol, Tramadol. (Learn more about opioid addiction and recovery…)
    • Smoking cessation: Varenicline.
    • Tranquilizers, sleeping pills, benzodiazepines: Alprazolam, Baclofen, Chlordiazepoxide, Clonazepam, Clorazepate, Diazepam, Eszopiclone, Flurazepam, Ramelteon, Triazolam, Zaleplon, Zolpidem. (Learn more about benzodiazepine addiction and recovery…)

    Important: This information is not complete. You should always consult your physician when making decisions about your health.

    Treatment of Depression

    Cognitive Behavioral Therapy for Depression

    Cognitive behavioral therapy (CBT) is a step-by-step method for identifying your negative thinking and replacing it with healthier thinking. It changes your inner dialogue. Numerous studies have shown that cognitive behavioral therapy is effective for treating a number of mental health conditions including depression.[24] (Learn more about cognitive behavioral therapy…)

    How Cognitive Therapy Can Help

    • Identify your negative thinking and replace it with healthier thinking.
    • Find better ways to cope with problems or crises.
    • Develop better coping skills.
    • Learn to recognize your hot-button issues and how to not be effected.
    • Improve your self-confidence and take control of your life.
    • Set realistic goals so that you are not as hard on yourself.

    Stress Management, Meditation and Mindfulness for Depression

    Not too long ago, medicine dismissed the importance of the connection between the body and mind. It did not believe that your emotional state could cause physical problems. Now meditation and mindfulness are being used by medicine. The evidence is overwhelming that they can help in the treatment of a number of mental health conditions including depression.[25] (Learn more about stress management, meditation, and mindfulness, including how to meditate and how meditation can help…)

    Antidepressants

    The most effective treatment of depression is a combination of psychotherapy and antidepressants.[26] Antidepressants treat the symptoms of depression, while psychotherapy improves your thinking and reduces the risk of depression in the future. (Learn more about antidepressants, including choices, benefits, side effects, and guidelines...)

    St John’s Wort (A Natural Antidepressant)

    Medical trials have shown that St. John’s Wort (hypericum) is as effective as prescribed antidepressants for mild depression and can have fewer side effects. (Learn more about St. John’s Wort – hypericum…)

    Five Things You Can Do About Your Depression

    Lifestyle changes for depression are just as important as prescribed medication. If you take an antidepressant but don’t take care of yourself, the antidepressant has less chance of working.

    1. Don’t Self-Medicate with Drugs or Alcohol

    Drugs and alcohol are brain depressant. They may temporarily relieve your mood, but they quickly turn against you and make you feel more depressed.

    2. Get Enough Sleep

    Poor sleep or not enough sleep can worsen depression. Sleep-deprived individuals are more likely to classify neutral images as “negative,” which can lead to negative thinking. Learning stress management methods such as how to meditate can improve your quality of sleep.

    3. Mild Physical Activity

    Mild physical activity (walking) increases your body’s production of natural antidepressants. Don’t think in terms of exercise. If you’re depressed, the idea of exercise is too much. Even mild activity can help reduce depression symptoms and help your antidepressant work better.

    4. Follow the Mediterranean Diet

    The Mediterranean diet has been shown to be the most effective overall diet for treating depression. Some isolated nutrients that also help are omega-3 and omega-6 fatty acids. Complex carbohydrates can increase production of natural antidepressants, such as serotonin.

    5. Consider Light Therapy

    Light therapy is effective for most kinds of depression, not just seasonal affective disorder. Light therapy consists of sitting in front of a full spectrum light that produces 10,000 lux for 20-30 minutes in the morning. Light therapy can be so effective that it must be carefully used in people with bipolar disorder, because it can induce mania. Consult with your physician before considering light therapy.

    Family Support

    Mental health issues are family issues. Family and friends need to learn what helps when supporting someone with depression, what doesn’t help, and the importance of taking care of oneself. Understand that it’s normal to have some negative feelings when helping someone with depression. (Learn more about helping someone with depression...)

    Things You Can Do for Yourself

    • Do not work harder than the person you’re trying to help. This is the most important guideline in family support, and it is the most effective way to decide how much or how little to do.
    • Working harder than the other person will only exhaust you and make them resent you because they will feel that you are pushing too hard.
    • If the individual doesn’t want to do anything to help themselves, you can still do something by being an example of balance and self-care.
    • Loving someone with a mental health condition can be exhausting. You also need time to recover. Take care of yourself.
    • Avoid self-blame. You can’t control another person’s decisions, and you can’t force them to change.
    • Being a caretaker is not good for you or the other person. Understand that there is only so much you can do.
    • Ask for help. Talk to a professional. Go to a support group. You may need as much support as they do.

    Links

    A list of depression links to organizations, agencies, self-help groups, and forums for dealing with depression. The most important step you can take in overcoming depression is reaching out and asking for help.

    Find Help

    Visit www.IWantToChangeMyLife.org/findhelp for crisis phonelines, counselors, therapists, psychologists, and other mental health professionals. You can change your life.

    References

    1. National Comorbidity Survey, Lifetime Prevalence of DSM-IV Disorders.  https://www.hcp.med.harvard.edu/ncs/ftpdir/NCS-R_Lifetime_Prevalence_Estimates.pdf.
    2. Kessler, R. C., Berglund, P., Demler, O., Jin, R., et al., Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry, 2005. 62(6): p. 593-602.
    3. Lopez, A. D., Mathers, C. D., Ezzati, M., Jamison, D. T., et al., Global and regional burden of disease and risk factors, 2001: systematic analysis of population health data. Lancet, 2006. 367(9524): p. 1747-57.
    4. American Psychiatric Association, DSM-5 The Diagnostic and Statistical Manual of Mental Disorders. 5 ed, ed. D. Kupfer: American Psychiatric Association.
    5. Eaton, W. W., Shao, H., Nestadt, G., Lee, H. B., et al., Population-based study of first onset and chronicity in major depressive disorder. Arch Gen Psychiatry, 2008. 65(5): p. 513-20. PMC2761826.
    6. Moffitt, T. E., Harrington, H., Caspi, A., Kim-Cohen, J., et al., Depression and generalized anxiety disorder: cumulative and sequential comorbidity in a birth cohort followed prospectively to age 32 years. Arch Gen Psychiatry, 2007. 64(6): p. 651-60.
    7. Mantere, O., Suominen, K., Leppamaki, S., Valtonen, H., et al., The clinical characteristics of DSM-IV bipolar I and II disorders: baseline findings from the Jorvi Bipolar Study (JoBS). Bipolar Disord, 2004. 6(5): p. 395-405.
    8. Kroenke, K., Spitzer, R. L., & Williams, J. B., The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med, 2001. 16(9): p. 606-13. PMC1495268.
    9. Gilbody, S., Richards, D., Brealey, S., & Hewitt, C., Screening for depression in medical settings with the Patient Health Questionnaire (PHQ): a diagnostic meta-analysis. J Gen Intern Med, 2007. 22(11): p. 1596-602. PMC2219806.
    10. Roseman, M., Kloda, L. A., Saadat, N., Riehm, K. E., et al., Accuracy of Depression Screening Tools to Detect Major Depression in Children and Adolescents: A Systematic Review. Can J Psychiatry, 2016. 61(12): p. 746-57. PMC5564894.
    11. Angst, J., The course of affective disorders. Psychopathology, 1986. 19 Suppl 2: p. 47-52.
    12. Kübler-Ross, Elisabeth, On death and dying: Macmillan, 1969.
    13. Schuckit, M. A., Tipp, J. E., Bergman, M., Reich, W., et al., Comparison of induced and independent major depressive disorders in 2,945 alcoholics. Am J Psychiatry, 1997. 154(7): p. 948-57.
    14. Bovasso, G. B., Cannabis abuse as a risk factor for depressive symptoms. Am J Psychiatry, 2001. 158(12): p. 2033-7.
    15. Patton, G. C., Coffey, C., Carlin, J. B., Degenhardt, L., et al., Cannabis use and mental health in young people: cohort study. BMJ, 2002. 325(7374): p. 1195-8. 135489.
    16. Kessler, R. C., Chiu, W. T., Demler, O., Merikangas, K. R., et al., Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry, 2005. 62(6): p. 617-27. PMC2847357.
    17. Gerrits, M. M., Vogelzangs, N., van Oppen, P., van Marwijk, H. W., et al., Impact of pain on the course of depressive and anxiety disorders. Pain, 2012. 153(2): p. 429-36.
    18. Kroenke, K., Outcalt, S., Krebs, E., Bair, M. J., et al., Association between anxiety, health-related quality of life and functional impairment in primary care patients with chronic pain. Gen Hosp Psychiatry, 2013. 35(4): p. 359-65.
    19. Fishbain, D. A., Cutler, R., Rosomoff, H. L., & Rosomoff, R. S., Chronic pain-associated depression: antecedent or consequence of chronic pain? A review. Clin J Pain, 1997. 13(2): p. 116-37.
    20. Kendler, K. S., Gatz, M., Gardner, C. O., & Pedersen, N. L., A Swedish national twin study of lifetime major depression. Am J Psychiatry, 2006. 163(1): p. 109-14.
    21. Kendler, K. S., & Aggen, S. H., Time, memory and the heritability of major depression. Psychol Med, 2001. 31(5): p. 923-8.
    22. Qato, D. M., Ozenberger, K., & Olfson, M., Prevalence of Prescription Medications With Depression as a Potential Adverse Effect Among Adults in the United States. JAMA, 2018. 319(22): p. 2289-98.
    23. Rogers, D., & Pies, R., General medical with depression drugs associated. Psychiatry (Edgmont), 2008. 5(12): p. 28-41. PMC2729620.
    24. Hofmann, S. G., Asnaani, A., Vonk, I. J., Sawyer, A. T., et al., The Efficacy of Cognitive Behavioral Therapy: A Review of Meta-analyses. Cognit Ther Res, 2012. 36(5): p. 427-40. PMC3584580.
    25. D'Silva, S., Poscablo, C., Habousha, R., Kogan, M., et al., Mind-body medicine therapies for a range of depression severity: a systematic review. Psychosomatics, 2012. 53(5): p. 407-23.
    26. Arnow, B. A., & Constantino, M. J., Effectiveness of psychotherapy and combination treatment for chronic depression. J Clin Psychol, 2003. 59(8): p. 893-905.
    Last Modified: November 3, 2018