Is Depression a Disease?

Depression as a Systemic Disease

Depression can be considered a systemic disease.

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A common question as we make advances in our understanding of depression is the following: Is depression a disease? To answer this question, it is helpful to consider both the features of depression as well as the meaning of various ways of conceptualizing depression as a mental disorder, illness, or disease.

Depression as a Systemic Illness

There is an increasing trend toward evidence supporting the theory of depression as a systemic disease.

A systemic illness is one that affects the whole body rather than just a single body part or organ system. This differs from a localized illness that only affects a single part of the body.

Definitions of mental and physical illness may overlap more than researchers previously thought—such that the distinction between illness of the mind and illness of the body is blurred. Could it be that depression, an illness that can be treated with psychotherapy, can have an influence on the physical body, and if so, what does that mean?

Labeling depression as a disease does not entirely capture the complex nature of the illness. However, it is a move toward understanding it as a disorder of both the mind and body.

What the Research Says

Evidence to support depression as a systemic disease comes in the form of biological changes that are seen in patients with depression. For example, inflammation, neuroendocrine regulation, platelet activity, autonomic nervous system activity, and skeletal homeostasis can all be influenced by depression.

In this way, it is possible to see how depression could have a relationship to conditions like heart disease, cancer, and diabetes—the very illnesses to which it is being compared. If depression is related to your immune response, how might that look?

A meta-analysis conducted at the University of Granada and published in the Journal of Clinical Psychiatry examined changes in the bodies of depressed people based on 29 previously published studies. It was found that depression caused an imbalance in antioxidants and free radicals that can potentially damage the cells of the body, also referred to as oxidative stress.

After these patients with depression received treatment, their levels of malondialdehyde, a biomarker indicating oxidative stress went back down to healthy levels. In addition, it was shown that their levels of zinc and uric acid rose back to normal levels after treatment.

Physical Indicators of Depression

Research may help to explain why people with depression often complain of physical symptoms like sleeping too much or too little, fatigue, and appetite changes. It is suggested that this may also help to explain why patients with depression tend to have shorter lifespans.

We also know that some medical conditions can lead to depressive symptoms, such as hypothyroidism.

Depression is not simply a problem of the mind, but rather a complex disorder with both biological and social causes connecting the mind and body.

What the Future Holds

This type of research also suggests advances in how we diagnose depression, beyond screening from a list of symptoms. In the not too distant future, people may even be able to receive a biomarker test that indicates their level of depression.

What's in a Name?

Does it matter if we call depression a mental disorder or a systemic disease? Confusion can stem from calling it strictly a disease, along the lines of diabetes, because we know that you can't treat a disease like diabetes with talk therapy.

On the other hand, considering depression as strictly a mental disorder doesn't capture the complex nature of the illness and may not motivate people experiencing it to try methods of getting better that don't just involve their mind.

Features of Depression

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), depression is diagnosed when five or more of the following symptoms (summarized for the purposes of this article) have been present in the same two-week period and represent a change from your previous functioning.

At least one of the symptoms must be either depressed mood or loss of interest or pleasure:

  • Depressed mood most of the day, nearly every day
  • Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day
  • Significant weight loss or weight gain (without intentional dieting) or decrease or increase in appetite nearly every day
  • Insomnia or hypersomnia nearly every day
  • Psychomotor agitation or retardation nearly every day
  • Fatigue or loss of energy nearly every day
  • Feelings of worthlessness or excessive or inappropriate guilt nearly every day
  • Diminished ability to think or concentrate, or indecisiveness nearly every day
  • Recurrent thoughts of death or recurrent suicidal ideation

If you are having suicidal thoughts, contact the National Suicide Prevention Lifeline at 1-800-273-8255 for support and assistance from a trained counselor. If you or a loved one are in immediate danger, call 911.

For more mental health resources, see our National Helpline Database.

In addition, the symptoms must cause significant distress or impairment in daily life and not be attributed to another medical condition or the effects of substance use.

Considering the above list of symptoms, it's troubling to think about depression strictly as a disorder of the mind. Indeed, the many bodily manifestations of depression suggest that there is more going on than we once thought.

It's important to remember that the mind and body are both parts of a larger system and that they interact and influence each other.

Illness Definitions

Depression has been referred to as a mental disorder, mental illness, and a systemic disease. While there is certainly overlap between these terms, each has a unique definition that we can consider when trying to understand what exactly depression is.

  • A mental disorder can be considered an illness that disrupts your normal mental functioning (just as a physical disorder would be one that disrupts your normal physical functioning). Examples of mental disorders are depression, anxiety disorders, and post-traumatic stress disorder (PTSD).
  • A mental illness would be considered largely the same thing as a sickness affecting the mind. Examples of mental illness are the same as above, though some might lean toward thinking of schizophrenia or bipolar disorder—illnesses with more obvious symptoms and that are traditionally thought of as being treated with medication first.
  • In contrast, a disease is generally considered a problem of the body's functioning that produces symptoms. Examples might include heart disease, diabetes, and cancer. A systemic disease is one that affects the entire body, not just one organ or part.

It's easy to see how considering depression a systemic disease along the likes of hypertension or diabetes will require a massive shift in traditional perspectives of mental illness and mental disorders.

However, the fact that this is not the traditional way of thinking about depression does not mean that it cannot be accurate. Over time, many of our perceptions of the world change as we gain an appreciation for our past misconceptions. This might also be the case for depression.

Treating Depression as a Systemic Illness

If depression is considered within the context of a systemic illness, what does this mean in terms of treatment? Beyond the obvious connection to pharmacological treatments such as antidepressant medication, it suggests that changes that impact the systems of the body may also help to alleviate depression. While mind-focused treatments are important, those that target systems of the body may also be key.

For example, treatment approaches that address physical factors such as nutrition, sleep, and exercise can be a useful complement to medical and psychotherapeutic treatments.

Taking a more whole-body approach can be an effective approach when treating depression. In many cases, combining psychotherapy, medications, and self-care strategies can be more impactful than simply relying on a single approach alone.

Coping With Depression

If you are living with depression, it is important to know how to cope with it both in terms of your mind and body. While talk therapy such as cognitive-behavioral therapy (CBT) targets the mental causes of depression, and medication can target chemical imbalances in the body, there are other approaches you can take as well.

In general, promoting body and cellular health will be beneficial if you have depression. Some steps you can take to cope include:

  • Getting regular exercise
  • Spending time outdoors (in sunlight)
  • Maintaining a regular sleep schedule
  • Eating a healthy diet

When you consider depression as a whole-body illness, it makes sense to approach it from multiple angles. Of course, your ability to make these changes will depend on the severity of your depression.

A Word From Verywell

Most people with depression don't seek help or receive it. They may feel that their depression is a moral failing on their part. In this way, referring to depression as a systemic disease may help to remove some stigma from this complex disorder.

Just because depression can be treated with psychological therapy does not mean the physiological ramifications are any less severe. Seek help for your depression symptoms, just as you would any other illness. Severe cases of depression, in particular, are best treated by a mental health professional who can devise a plan that combines multiple components such as medication, talk therapy, and lifestyle changes.

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  1. Jiménez-Fernández S, Gurpegui M, Diaz-Atienza F, Perez Costillas L, Gerstenberg M, Correll C. Oxidative stress and antioxidant parameters in patients with major depressive disorder compared to healthy controls before and after antidepressant treatment: Results from a meta-analysis. The Journal of Clinical Psychiatry. 2015; 76(12): 1658-1667. doi:10.4088/JCP.14r09179

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