While it is true that social and environmental factors can cause depression, the mechanism by which it occurs physiologically is unknown yet.
However, it is believed that there is a complex interaction between certain chemical substances, which mediate certain functions in the brain and their corresponding receptor. These chemical substances are called neurotransmitters.
A receptor, which can be located on a cell or inside it, is like the lock of a key while a neurotransmitter is the key. When a neurotransmitter binds to this lock, activities are activated within the cells.
Different trials have revealed that serotonin (5-HT) activity is a key neurotransmitter that is involved in major depressive disorder although brain-derived neurotrophic factor (BDNF), dopamine (DA), norepinephrine (NE) and glutamate are also implicated.
All these chemicals are involved in the regulation of emotions.
Just like every other psychiatric disorders, major depressive disorders is a set of disorders that can be caused by multiple factors that does not preclude environmental and genetic factors.
So what are the likely causes or risk factors of depression?
* Genetics: Life is about influence and we are all a product of influence. Studies have revealed over and again that family members who stay together can suffer from depression. For instance, study has it that if an identical twin is depressed, the other twin has a 70% chance of being depressed later or sooner in life. So it is when a parent or child has it. However, it is good to bear in mind that many people who have been diagnosed of depression have no trace of a family history of it.
* Environmental factors: If you are constantly exposed to abuse, financial poverty, violence or neglect, chances are that your degree of vulnerability to depression is very high.
* Changes in the neurotransmitter levels in the brain: Any alteration in any of the chemicals earlier mentioned to be involved in emotions can produce those symptoms related to depression. This alterations could either occur in their production or utilization.
* Personality: If you are battling with poor self-image, are easily tripped by stress, or you are generally pessimistic about life, you stand a higher chance of experiencing depression.
* Psychological and social factors: life events like work place issues, bereavement, heartbreaks, heavy financial loss, failed business, medical concerns etc. can trigger episodes of depression.
* Stress: Sometimes, life might present to us demanding situations or deadlines that are overwhelming. If this keeps re-occurring, it might well predispose us to episodes of depression.
* Poor coping strategies: While some people are trained on how to handle situations that might be ideally really tasking, energy consuming or hard to grasp, some other people might come short here. So when life hits them hard, they find it pretty difficult to successfully handle whatever it is and before you know it, they are down there with depression.
* Drugs: These could either be recreational drugs or prescription drugs. Recreational drugs are used not for medical reasons but for leisure or fun while prescription drugs are used for medical purposes. Examples of recreational drugs include: caffeine, alcohol, tobacco, amphetamine, cannabis, mushroom, mdma, methamphitamine etc. Prescription drug examples on the other hand include beta-blockers, corticosteroids and interferon etc.
* Serious head injury.
* A personal history of episodes of major depression.
* Medical conditions like diabetes, cancer, chronic obstructive pulmonary disease (COPD), or heart related conditions can increase one’s likelihood of developing depression symptoms.
* Chronic pain such as that related to chronic medical illness can negatively influence sleep patterns and other bodily activities which may then cause the person to fall into depression.
* Sexual abuse
* Age: Older adults for instance, who have medical issues that eventually render them unable to move around without requiring the assistance of someone, may become alienated from meaningful social networks and interactions.
How depression can be diagnosed?
If you or someone close to you is manifesting any of the symptoms of depression, it is usually advised that medical help be sought immediately especially when symptoms have been recurring for at least 2 weeks.
As much as you can, do well to tell the health care provider all the symptoms you have been experiencing. Diagnosis may involve doctors physically examining you, blood tests and filling of a questionnaire in the clinic.
For one to be diagnosed with depression, one must manifest at least four of these symptoms amongst many other pointers that would be utilized by a health expert based on instructions contained in the 2013 Diagnostic and Statistical Manual of Mental Disorders:
* Patients must have complained of disturbances of sleep or eating.
* Patients must feel drained physically or lack concentration.
* Patients must have issues with self-image.
* Patients must have thought of or attempted suicide.
There are no current valid laboratory tests available for specifically diagnosing depression, however, there are a couple of screening tools (scales) that can be utilized for this purpose.
Following are common self-reporting screening tools for depression:
* Beck Depression Inventory (BDI) or the Beck Depression Inventory-II (BDI-II): This is a 21-question symptom-rating scales that provides a 0-63 severity score.
* Zung Self-Rating Depression Scale: This is a 20-item self-report survey.
* Patient Health Questionnaire-9 (PHQ-9): This is a 9-item depression scale where each item is scored from 0-3 with a severity score range of 0-27.
* BDI for primary care: BDI for primary care is a 7-question scale adapted from the BDI.
* Center for Epidemiologic Studies-Depression Scale (CES-D): CES-D is a 20-item instrument that allows patients to honestly evaluate their feelings, behavior, and outlook from the previous week.
In contrast to the above listed self-report scales for depression, the Hamilton Depression Rating Scale (HDRS), which is a 17 0r 21 item survey, employs trained professionals, not the patient, in the diagnostic effort. The HDRS is scored from 0-2 or 0-4, with a total score of 0-7 being considered normal and scores of 20 or more signifying moderately severe depression.
Another notable diagnostics tool used for depression is the Geriatric Depression Scale (GDS). A typical GDS has 30 items, however, a shorten version containing 15 items exists.
The GDS, although primarily developed for older adults, now finds use for diagnosis in younger adults.
“NIMH » Depression” https://www.nimh.nih.gov/health/topics/depression/index.shtml
Depression: Practice Essentials, Background, Pathophysiology” https://emedicine.medscape.com/article/286759-overview
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM-5), Fifth edition. 2013.
“Depression Central: Types, Causes, Symptoms, Statistics, & Treatment” https://www.psycom.net/depression.central.html