WHAT IS DEPRESSION?
The prevalence of depression is increasing worldwide. According to the World Health Organization (WHO, 2023), more than 280 million people suffer from depression globally, making it one of the leading causes of disability. Depression is a serious, complex medical illness that not only affects emotions and mental health but also has significant physiological impacts on physical health.
Neurobiological studies show that depression disrupts brain neurotransmitters such as serotonin, dopamine, and norepinephrine, which regulate mood, sleep, and appetite. Over time, this imbalance slows both mental and physical processing. Severe cases can even impair motor function, increasing the risk of neurological complications, including paralysis-like syndromes.
In addition, patients with chronic illnesses (arthritis, cancer, psoriasis, diabetes, heart disease, thyroid disorders, vitamin deficiencies, infertility, and multiple sclerosis) are at higher risk because both the illness and depression reduce quality of life.
SYMPTOMS OF DEPRESSION
Like other medical conditions, depression has recognizable warning signs. A depressed person may face the following symptoms:
• Poor concentration or difficulty in making decisions
• Low energy and persistent fatigue
• Feeling hopeless about the future
• Low self-esteem
• Feeling helpless or worthless
• Disrupted sleep patterns
• Persistent sadness
• Change in appetite or weight
• Loss of interest in previously enjoyable activities
• Repeated thoughts of death or suicide
HOW TO DIFFERENTIATE DEPRESSION FROM NATURAL SADNESS OR GRIEF
It is important to remember that not all sadness is depression. Clinical depression is diagnosed when symptoms persist for two weeks or more and are accompanied by a noticeable decline in daily functioning (American Psychiatric Association, DSM-5).
Unlike temporary sadness, depression is persistent and disabling.
FACTORS RESPONSIBLE FOR DEPRESSION
Depression does not arise from a single cause but is usually the result of multiple interacting factors. Some important contributors include:
AIR POLLUTION
For example, environmental factors play a major role. A study published in JAMA Psychiatry (2019) found that long-term exposure to fine particulate matter (PM2.5) was associated with a higher risk of depression, particularly among older adults. Air pollution may alter brain structure, trigger systemic inflammation, and affect neurotransmitter activity.
GENETIC
On the other hand, genetics also play a crucial role. Twin studies reveal that heritability accounts for about 40–50% of depression risk. Variations in genes regulating serotonin transport (such as 5-HTTLPR) increase susceptibility to depression, anxiety disorders, and social phobia.
GENDER
Similarly, gender differences have been observed. Women are nearly twice as likely as men to develop depression (WHO, 2022). Hormonal changes during menstruation, pregnancy, postpartum, and menopause are major contributors, along with social stressors.
BEREAVEMENT
Life events also matter. Severe loss whether the death of a loved one, end of a relationship, or job loss can trigger major depressive disorder.
AGE
Age is another important factor. Older adults often experience depression due to isolation, cognitive decline, and chronic illness. The Lancet Healthy Longevity (2021) reported that untreated depression in elderly individuals increases risks of dementia and heart disease.
TRAUMATIC CONDITIONS
In addition, trauma during childhood leaves long-term marks. The CDC-Kaiser ACE Study found that adverse childhood experiences strongly increase lifetime risk of depression.
CHRONIC ILLNESS
Finally, chronic illnesses significantly contribute. For example, people with diabetes are 2–3 times more likely to experience depression (American Diabetes Association, 2022). This shows how physical health and mental health are deeply connected.
NEGATIVE CONSEQUENCES OF DEPRESSION ON THE BODY
Depression is not limited to the brain. Its consequences spread throughout the body in the following ways:
CHANGES IN EATING HABITS AND BODY WEIGHT
To begin with, depression disrupts appetite-regulating hormones like leptin and ghrelin. Some people overeat, leading to obesity, while others lose appetite due to stress-induced gastrointestinal dysfunction, resulting in weight loss.
HEART DISEASES AND DEPRESSION
Furthermore, depression strongly affects heart health. A landmark study in Circulation (2017) found that depression independently increases the risk of coronary artery disease and stroke. Cortisol overproduction raises blood pressure, worsens insulin resistance, and promotes atherosclerosis.
FATIGUE AND DEPRESSION
In addition, fatigue is one of the most disabling features of depression. Research shows that pro-inflammatory cytokines (IL-6, TNF-alpha) alter brain signaling, which explains why depressed individuals feel constantly exhausted.
PAIN IN DIFFERENT PARTS OF THE BODY
Another consequence is unexplained pain. According to the NIH, nearly 65% of depressed patients report physical pain, such as headaches, muscle pain, and chest pain, even in the absence of injury.
INFERTILITY AND DEPRESSION
Depression can also influence reproductive health. Hormonal imbalances and reduced sexual desire act as hidden risk factors for infertility. Research in Fertility and Sterility (2015) showed that untreated depression in women undergoing fertility treatments lowered success rates significantly.
INFLAMMATORY DISORDERS AND DEPRESSION
Moreover, depression and inflammation often fuel each other. Elevated inflammatory markers like C-reactive protein are common in depressed patients, increasing the risk of arthritis, diabetes, and IBS.
PARALYSIS AND DEPRESSION
Finally, one of the most concerning associations is paralysis. A study in Neurology (2021) reported that people with untreated depression have a higher risk of stroke and post-stroke paralysis. Depression also worsens recovery, creating a vicious cycle.
CONCLUSION
In summary, accurate diagnosis of depression is essential for protecting both mental and physical health. Research clearly shows that depression is not just “in the mind” but a systemic condition affecting the whole body.
Therefore, communication, a healthy lifestyle, supportive environments, and balanced nutrition are crucial preventive tools. For patients with chronic illness, early psychological counseling and integrated care can improve both mental health and quality of life despite disease burden.
FAQs
1. Can depression cause physical illness?
Yes. Depression is linked to heart disease, diabetes, obesity, inflammation, infertility, and even paralysis in severe cases.
2. Is depression genetic?
Partly. Around 40–50% of cases have a genetic link, but environment and lifestyle also play major roles.
3. How is depression different from sadness?
Sadness is temporary, while depression persists for at least two weeks and interferes with daily functioning.
4. Can lifestyle changes reduce depression risk?
Yes. Exercise, a balanced diet, social connections, and stress management help reduce the risk.
5. Do chronic illnesses increase depression risk?
Definitely. Patients with diabetes, cancer, arthritis, and heart disease are 2–3 times more likely to experience depression.
DISCLAIMER
This article is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you or someone you know is experiencing symptoms of depression, please seek help from a qualified healthcare provider. If you have thoughts of self-harm, contact your local emergency number or helpline immediately.
CALL TO ACTION
Depression is treatable, and recovery is possible. If you or your loved one is struggling, do not hesitate to reach out for professional support. Counseling, medical treatment, and lifestyle changes can significantly improve quality of life. Take the first step toward better mental and physical health today.
REFERENCES
1. World Health Organization (WHO). Depression Fact Sheet, 2023.
2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5).
3. JAMA Psychiatry. “Air Pollution and Risk of Depression in Older Adults.” 2019.
4. Circulation. “Depression and Cardiovascular Disease: An Updated Review.” 2017.
5. Fertility and Sterility. “Depression and Outcomes in Fertility Treatments.” 2015.
6. Neurology. “Depression and Risk of Stroke/Paralysis.” 2021. 7. National Institutes of Health (NIH). “Pain and Depression: Clinical Correlations.”