Depression is one of the most common mental disorders in the United States. The statistics collected by the National Institute of Mental Health on depression in the United States are very concerning. In 2016, 6.7% of all U.S. adults had at least one major depressive episode (16.2 million). If we focus only on teens, the prevalence jumps to 12.8%. The rates are even higher in adolescent females, 19.4%. In other words, almost 1 in every 5 female teens have experienced a major depressive episode.
Many people who suffer from depression don’t seek treatment. And out of the ones who seek treatment, many are not helped by these treatments. Typically, treatment is medication, talk therapy or both. Antidepressants are effective in treating 40% to 60% of patients. Similar success rates have been reported for psychotherapy treatments of depression (1).
Why do not treatments alleviate the suffering of more people? Is there any way we can increase the success rates of medical and non-medical treatments of depression?
I think the answer is a definite "yes." The causes of depression are heterogeneous. Thus, treatment providers should not use a generic treatment for depression. The following is a non-exhaustive list of potential causes for depression. Each cause deserves its own tightly fitted treatment option.
1. Chemical Imbalance
The balance of brain chemicals is crucial for healthy mood and behaviors. Some of the neurotransmitters that might be out of balance in depression are serotonin, dopamine, norepinephrine, acetylcholine, glutamate, and GABA.
Some of the strongest evidence for a genetic contribution to depression is the increase of risk in relatives of people who suffer from depression. A person who has a first-degree relative who suffered major depression has an increase in risk for the condition of 1.5% to 3% over one who has no first-degree relatives afflicted with depression.
3. Electric signal pathologies in the brain
There are two types of signals in the brain: chemical and electrical. While research has extensively studied the chemical imbalance hypothesis, there is very little to address the neuro-electrical pathologies related to depression. But, what has been known for centuries is that electric convulsive therapy temporarily alleviates symptoms of severe depression.
4. Medical conditions
One of the most common complications of chronic illnesses is depression. Professionals are advised to always check first for medical conditions before ascribing a mental disorder diagnosis. WebMD lists the prevalence of depression among patients with chronic illnesses (prevalence of depression in parentheses), heat attack (40-65%), Parkinson’s disease (40%), Multiple sclerosis (40%), cancer (25%), diabetes (25%) and chronic pain (30-54%).
Some prescription medications may cause depression. To name a few, beta-blockers for a heart condition, Accutane for acne (also increases the risk of suicide) and birth control pills. According to studies, medical illnesses or medications may be at the root of up to 10% to 15% (more or less depending on the medical condition) of all depressions.
6. Viral & autoimmune
Pathogens acting directly on the brain have been related to psychiatric symptoms. A Danish study examined the medical records of over 3 million people. They found that any history of hospitalization for infection was associated with a 62% increased risk of later developing a mood disorder (2). In addition, they reported that a past history of an autoimmune disorder increases the risk of a future mood disorder by 45%.
Women are twice as likely to develop depression as men. There are many reasons for this difference, but one has to do with hormonal differences. According to the Center of Disease Control, 11-20% of women suffer from postpartum depression. Again, there are many reasons, but one is hormonal.
Adverse childhood experiences increase the likelihood of later developing depression. For example, one study found that losing a parent (or both) during childhood increases the risk of depression in adulthood (3). One study showed that there is a graded relationship between exposure to adverse situations and the risk of depression (4).
9. Change of Season
Change of season is also related to depression. This type of depression is called Seasonal Affective Disorder (SAD).
A meta-analysis found a link between vitamin D deficiency and depression (5). Another study cautioned about sugar. They found that men who consumed 67 grams or more of sugar per day were 23% more likely to be diagnosed with depression in a five-year period than men who ate 40 grams or less (6).
11. Psycho-social factors
There is extensive literature on factors such as loneliness, job satisfaction, marital status, and depression. I will address this in future articles.
12. Sleep habits
There is a complex relationship between sleep and depression: poor sleep habits can cause or exacerbate depression, and depression causes sleep disturbances.
13. Media addiction
Social media can get overwhelming, lead to loss of productivity, decrease self-esteem and confidence and cause changes in mood. Also, some movies or TV series can trigger depression in some people. In 2009, many Avatar fans reported feeling depressed and some even felt suicidal (the Avatar blues).
Some personality types might be at a higher risk of depression, such as highly sensitive people with a troubled childhood.
15. Minority/majority status
16. Substance use history
Withdrawal from some drugs or a history of substance use can be related to depression.
Chronic stress increases cortisol and indirectly reduces brain neurotransmitters such as serotonin and dopamine, which can contribute to depression.
18. Old age
Of course depression is not a part of normal aging, but the older person is more vulnerable. There are many biological, social and psychological changes that occur with growing old. Some people struggle with the process of aging and this might culminate into a depression.
19. Where you live
Depression rates vary by country, state, and city. People living in urban areas have a higher risk than those living in rural areas. Risk also varies according to the geography of land—for example, suicide rate is related to altitude (7).
20. Loss of meaning or purpose
People who struggle to find meaning in their life or with concepts such as death might develop existential depression, or a loss of motivation to search for meaning or purpose.
For the treatment of depression to be effective, the causes have to be thoroughly explored—and a treatment program to directly address the causes has to be devised for each patient.
(1) Cuijpers, P. et al. (2013). A Meta-Analysis of Cognitive-Behavioural Therapy for Adult Depression, Alone and in Comparison With Other Treatments. CanJPsychiatry, 58(7): 376-385.
(2) Benros, M. E. et al. (2013). Autoimmune Diseases and Severe Infections as Risk Factors for Mood Disorders. JAMA Psychiatry, 70(8), 812-820.
(3) Berg, L., Rostila, M. and Hjern, A. (2016). Parental Death During Childhood and Depression in Young Adults- A National Cohort Study. Journal of Child Psychology and Psychiatry, 57(9), 1092-1098.
(4) Chapman, D. P. (2004). Adverse Childhood Experiences and the Risk of Depressive Disorders in Adulthood. Journal of Affective Disorders, 82: 217-225.
(5) Anglin, R. E. S. et al. (2013). Vitamin D Deficiency and Depression in Adults: Systematic Review and Meta-Analysis. BJPsych, 202, 100-107.
(6) Knupper, A. et al. (2017). Sugar Intake from Sweet Food and Beverages, Common Mental Disorder and Depression: Prospective Findings from the Whitehall II Study. Scientific Reports, 7, 6287.
(7) Lederbogen, F. et al. (2011). City Living and Urban upbringing Affect Neural Social Stress Processing in Humans. Nature, 474, 498-501.