Depression in a Nutshell

depression in a nutshell
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Difference Between Depression and Low Mood

Depression is a very common mental disorder, also known as Major Depressive Disorder (MDD). Depression is different from ordinary depressive mood or low mood. The latter is a normal emotional state common to human beings. It usually refers to emotions such as negativity, sadness, and disappointment for a period of time. Having this emotional state doesn’t necessarily mean you have depression. Depressive mood usually does not last too long, does not impact one’s life and work significantly, the symptoms are not very severe and it is usually triggered by specific life events. However, the symptoms, duration and interference of depression are different.

Depressive Symptoms

  1. Feeling down (feeling sad, irritable, empty, etc.) most of the time almost every day for more than two consecutive weeks, and not interested in doing anything, even things that you liked before.
  2. Fatigue.
  3. Appetite becomes lower or higher, and weight change. 
  4. Insomnia or difficulty waking up.
  5. Low self-esteem, self-blame, and suicidal thoughts.
  6. Negative thinking.
  7. Poor concentration.
  8. Physically slowed down.
  9. Physical discomfort despite normal physical examination (such as pain, fatigue, weakness, etc.).
  10. Indecision.

Many people have depression and anxiety at the same time, click here to know more about anxiety.

Note: Depressive symptoms vary for each person, and you don’t need to have all the above symptoms to meet the diagnostic criteria. Do not self-diagnose based solely on the list of symptoms above and any online depression quiz. If you suspect you are suffering from depression, please seek professional assessment and treatment from mental health professionals, such as registered psychologists, family doctors, and psychiatrists. 

Causes of Depression

The causes of depression are complex, resulting from the combined effects of environmental, biological, psychological, and behavioural factors.

Environmental Factors:

  1. Negative life events, such as the loss of a loved one, traumatic events (such as being abused, raped, accidents, etc.), losing a job or not doing well at work, family conflicts, relationship tensions, etc.
  2. Interpersonal factors such as loneliness, interpersonal conflict, social pressure, etc.
  3. Work environment, such as long-term high-pressure work, job burnout, toxic work environment, job frustration, etc.
  4. Environmental pollution, such as noise pollution.
  5. Chronic poverty or financial hardship.
  6. Unfair social environment, such as gender/race/class discrimination, political corruption, etc.
  7. Childhood trauma, also known as Adverse Childhood Experiences (ACE), such as emotional neglect, physical or psychological abuse, domestic violence, parental divorce or separation, family members suffering from mental disorders, etc.

Biological Factors:

  1. Traumatic Brain Injury: An injury to some crucial parts of the brain caused by an external force.
  2. Hormonal changes: Hormonal changes, such as those caused by pregnancy, menopause, or thyroid disease.
  3. Heredity: If a family member suffers from depression, the next generation has a higher risk of developing it.
  4. Chronic illness: Chronic illnesses such as chronic pain, heart disease, stroke, or cancer can increase the risk of depression.
  5. Long-term sleep problems: Long-term sleep disturbances or insomnia can increase the risk of depression.
  6. Substance abuse: People with alcohol or drug abuse also have an increased risk of depression.
  7. Nutrition: A healthy and regular diet plays a significant role in mood, many years of scientific research showed a strong connection between gut microbiome and brain/mental health . Excessive intake of inflammatory foods (e.g., fried food, fatty food, processed food) and high-sugar foods may lead to depression. Eating more fermented foods, high-fibre foods, and foods rich in omega-3, vitamin B, and vitamin D can help relieve depression.

Psychological Factors:

  1. Thinking styles, including but not limited to (a) selectively focusing on the negative side of things and ignoring the rest of the picture; (b) jumping to conclusion, assuming that the information you know must be accurate and comprehensive, so you can quickly conclude; (c) catastrophic thinking, thinking that things will go so badly that you are completely unable to cope; ( d ) all-or-nothing, if one thing is not white, it must be black; (e) perfectionism, if one thing If you can’t do your best, you’d rather not start.
  2. Self-criticism, you hold very high standards and expectations for yourself; as long as you fail to meet the standards in your mind, you will criticize yourself and think that you are not good enough.
  3. Repressing emotions, you think that you should not have any negative emotions, so once there are negative emotions, you will suppress them in every possible way. It often results in hypersensitivity to emotions or becoming emotionally numb.
  4. Avoiding all uncomfortable feelings, you avoid everything that makes you feel uncomfortable; it will gradually lead to life becoming more and more limited, and, thus, more depressing.
  5. A sense of meaninglessness in life, such as feeling confused about one’s own life, work, interpersonal relationship, family relationship, and intimate relationship, thinking that there is no sense of meaning, but you are unable to change, and thus starting to be depressed.

Behavioural factors:

  1. Lack of exercise can lead to an increased risk of depression.
  2. Lack of outdoor activities and staying indoors for a long time are not conducive to a good mood.
  3. Inadequate problem-solving or communication skills, if you can’t cope with various life difficulties or interpersonal conflicts, you will be more likely to be frustrated, which can lead to depression.
  4. If you don’t do more meaningful things, such as spending most of your time on activities such as cellphones and watching TV, it will be easier to feel depressed.

The environmental, biological, psychological and behavioural factors mentioned above interact to have an impact on a person’s mood. For example, a person who has been in a toxic working environment for a long time and is often deliberately made things difficult by their boss and isolated by their colleagues. Also, they firmly believe they are incapable of changing jobs, so they can only choose to tolerate it. As a result, they feel physically and mentally exhausted after getting off work every day and can’t do anything else. They can only lie on the couch and look at their cellphone. Their sleep quality is very low, and they always feel tired during the day. As time goes by, they start to lose interest in doing anything. Moreover, they begin to have neck, shoulder and lower back pain caused by long-term office work. They increasingly feel that life is meaningless.

Treatments of Depression

Because the causes of depression are very complex, the treatments of depression also require a diverse approach, specifically including the following types of treatment:

Drug Treatments

Commonly used medications for depression include selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), atypical antidepressants, tricyclic antidepressants (Tricyclic and tetracyclic antidepressants) and monoamine oxidase inhibitors (MAOI), etc. However, it’s worth noting that not all people with depression need to take medication, and every drug has some adverse reaction and dependency. Therefore, people with depression need to communicate closely with their family doctors or psychiatrists regarding questions like “do I need to take medication”, “what medications to take” and “what are the adverse reaction and withdrawal symptoms of the medication”.  


A comprehensive study in 2023 showed that psychotherapy was as effective as drug therapy in the short term and more effective in the long term. Many psychotherapy approaches are pretty effective on depression, such as Cognitive Behavioral Therapy (CBT), Acceptance and Commitment Therapy (ACT), Emotion-focused Therapy (EFT), psychodynamic therapy, interpersonal therapy (IPT), etc. Each approach has its uniqueness, and many professionals combine multiple approaches at the same time. Therefore, it is very important to find a right professional for you and a treatment you like.

Social Intervention

Actively improving one’s living environment is very helpful in improving depression. The living environment includes the natural environment and the social environment. Therefore, establishing healthy interpersonal and intimate relationships, doing jobs that are suitable and you are good at, choosing a workplace with a healthy culture, improving financial conditions and getting more in touch with nature are all good for improving depression. 

In addition to the treatments mentioned above, some self-help books can help you better understand and cope with depression. Here are some self-help books I recommend:

  1. Greenberger, Dennis, and Christine A. Padesky . Mind over mood: Change how you feel by changing the way you think . Guilford Publications, 2015.
  2. Harris, Russ. The happiness trap: How to stop struggling and start living. Shambhala Publications, 2022.
  3. Kwatra, Aman, et al. Transforming Emotional Pain: An Emotion-focused Workbook . Taylor & Francis, 2022.
  4. Hendel, Hilary Jacobs. It’s not always depression: Working the change triangle to listen to the body, discover core emotions, and connect to your authentic self. Random House, 2018.
  5. Kabat-Zinn, Jon, and Thich Nhat Hanh. Full catastrophe living: Using the wisdom of your body and mind to face stress, pain, and illness. Bantam, 2013.


1. Cuijpers, P., Miguel, C., Harrer, M., Plessen, C. Y., Ciharova, M., Ebert, D., & Karyotaki, E. (2023). Cognitive behavior therapy vs. control conditions, other psychotherapies, pharmacotherapies and combined treatment for depression: a comprehensive meta‐analysis including 409 trials with 52,702 patients. World Psychiatry, 22(1), 105-115.

2. Dozois, D. J., & Dobson, K. S. (2023). Treatment of psychosocial risk factors in depression. American Psychological Association. 

3. American Psychiatric Association. (2022). Depressive disorders. In Diagnostic and statistical manual of mental disorders (5th ed., text rev.). 

Click here to have a 10-minute free phone consultation with Dr. Houyuan Luo, a registered counselling/clinical psychologist in Toronto, Ontario.