Depression is not a disease. Anxiety is not a disease. However, these two conditions are very real and impact millions and millions of people around the world. In fact, depression affects 322 million people worldwide.  As many as 264 million people worldwide suffer from some type of anxiety disorder.  It is also common for a person to struggle with both conditions or have a history of both conditions.
Depression and anxiety are not diagnosed by blood work or other lab tests. Instead, the Diagnostic and Statistical Manual of Mental Disorders (DSM–5) is used to diagnose each condition. To be diagnosed with depression, a person must experience at least 5 of the following symptoms during a two-week period. Also, at least one of the symptoms has to be a 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 when not dieting or weight gain, or decrease or increase in appetite nearly every day.
A slowing down of thought and a reduction of physical movement (observable by others, not merely subjective feelings of restlessness or being slowed down).
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, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide. 
The following is needed to be diagnosed with General Anxiety Disorder:
The presence of excessive anxiety and worry about a variety of topics, events, or activities. Worry occurs more often than not for at least 6 months and is clearly excessive.
The worry is experienced as very challenging to control. The worry in both adults and children may easily shift from one topic to another.
The anxiety and worry are accompanied with at least three of the following physical or cognitive symptoms (In children, only one symptom is necessary for a diagnosis of GAD): a. Edginess or restlessness b. Tiring easily; more fatigued than usual c. Impaired concentration or feeling as though the mind goes blank d. Irritability (which may or may not be observable to others) e. Increased muscle aches or soreness f. Difficulty sleeping (due to trouble falling asleep or staying asleep, restlessness at night, or unsatisfying sleep) 
As you can see from these lists of diagnostic criteria, the impact depression and anxiety can have on your life is profound. But there is not a clearly defined disease process that is being diagnosed. That is an important factor that can be empowering and provide hope for people who are in the midst of struggling with these conditions!
What About Serotonin And Neurotransmitters?
The pervading theory of depression is the monoamine theory. It basically states that depletion or low levels of serotonin, norepinephrine and/or dopamine is the cause of depression. This explains the use of Serotonin Reuptake Inhibitor (SSRIs) medications in an attempt to treat people with depression. These drugs are designed to keep circulating levels of serotonin high in an attempt to prevent depressive symptoms. There is a problem with theory, especially in relation to serotonin. It is true that serotonin is located in the brain. But it is estimated that 90% or more of the body’s serotonin is located in the gastrointestinal tract. 
Just because most of the serotonin is in our guts, does that prove that low levels of serotonin are not the cause of depression? No it does not, but let’s look at the effectiveness of SSRIs. Studies have shown that antidepressants have “clinically negligible advantage over inert placebo” and only a 2 point difference on the Hamilton Rating Scale for Depression. Also, other studies have increased the levels of serotonin in the brain with use of tryptophan (an amino acid) with no change in depressive symptoms.  Other studies have shown that antidepressants have been prescribed to patients when they do not meet the criteria for a mental disorder and when there was no evidence-based indications for their use. 
There is another issue with the use of antidepressants. They have a long list of side effects, especially with long-term use. Some studies show that use of antidepressants can lead to movement disorders like Parkinson’s.  Other symptoms that are reported by people taking antidepressants include sexual dysfunction, being emotionally numb, withdrawal effects and issues with weight gain. They also report emotional symptoms that include reduced positive feelings, caring less about others, suicidality and not feeling like themselves.  It is interesting to note that in this same study, these same patients did report that the antidepressants were effective in improving overall levels of depression and quality of life.  As you can see, it is not always a black and white issue of using medications or not. The purpose of this last section is to provide information to you so that you can make the most informed decision possible.
Are There Any Other Options?
Yes. Yes there are. There is some new research evidence that points to depression being an inflammatory condition. One particular study showed that high sensitivity C-reactive protein can be used as an independent risk marker for depression.  People with depression have also been shown to have increased levels of pro-inflammatory cytokines like Tumor Necrosis Factor-alpha and Interleukin-6.  This activation of the inflammatory response, part of the immune system, appears to lead to over-activation of the Hypothalamic Pituitary Adrenal Axis (HPA Axis), disruption of normal serotonin metabolism and to the “sickness behavior” of severe depression.  This inflammatory component may also explain why depression commonly occurs in conjunction with other disease processes like cardiovascular disease.
How Do We Address Inflammation?
Fortunately, there are several things we can do to address inflammation. We can address the health of our gut. By doing so, we help our immune system to run efficiently and optimally. Remember that inflammation is a natural response and is part of healing. It is needed for us to be healthy. However, too much of it or too little of it will lead to issues with our health. Addressing gut health can help our immune system to produce just the right amount of inflammation. This can also help to reduce the over-activation of the HPA Axis due to the connection between the HPA Axis and our gut.
Managing stress is another way to reduce inflammation to the appropriate levels. By using stress management techniques, we will also decrease the activation of the HPA Axis.
One of the key factors in dealing with depression and anxiety is to take control of our thoughts. Our thoughts are nerve impulses. Think about how often your thoughts are negative or your self talk is negative. This leads to activation of the HPA Axis and the stress response… which leads to increased inflammation…which leads to an increased immune response…which leads to worsening of depression and anxiety…which leads to more negative thoughts and emotions…
Our thoughts are often wrong! We tend to assume the worst. We assume others see us as less important than them or we see ourselves as a failure. There are times when we experience difficulties in this life. We experience the loss of a loved one. We lose our job and wonder how are we going to provide for ourselves and our family. What symptoms are normal to feel during these seasons of life? That’s right, symptoms of depression and/or anxiety. These are stressful events that our bodies have to deal with. Let’s not compound the issue by beating ourselves up with negative self talk because we are having a normal response to our circumstances!
Cognitive Behavior Therapy (CBT) can help with controlling our thoughts. CBT is a practical, goal oriented psychotherapy treatment designed to change the pattern of thoughts and behavior that may be behind depression and anxiety.  It has been found to be helpful for dealing with depression and anxiety. The outcomes for CBT are better than antidepressants.  CBT is not just talking about your issues, but includes problem-solving between you and the therapist. This partnership helps you to determine the best course of action to address your specific issue.
What Is Your Identity?
If you have been diagnosed with or are experiencing symptoms of depression or anxiety, that is not your identity. That is not your label. You are a person who has worth and value. You may not feel that you are worthy or that you are valuable at this time, but I guarantee that you are. Please reach out and seek help if you are struggling. I believe that a multi-pronged approach is best. Have someone who can work with you to determine the appropriate dose and tapering protocol for any medication. Also have someone who can address the different diet and lifestyle factors that will address the underlying reasons for increased inflammation, gut dysfunction and HPA Axis dysfunction. Also have someone who you can talk to. By addressing all areas, you give yourself the best chance of regaining your health and quality of life.
This article is for educational use only. Nothing contained in this article should be considered, or used as a substitute for, medical advice, diagnosis or treatment. This article does not constitute the practice of any medical, nursing or other professional health care advice, diagnosis or treatment. Always seek the advice of a physician or other qualified health care provider with any questions regarding personal health or medical conditions. Never disregard, avoid or delay in obtaining medical advice from your doctor or other qualified health care provider because of something you have read in this article. If you have or suspect that you have a medical problem or condition, you should contact a qualified health care professional immediately. If you are in the United States and are experiencing a medical emergency, you should dial 911 or call for emergency medical help on the nearest telephone.
Yano, Jessica M. and Yu, Kristie and Donaldson, Gregory P. and Shastri, Gauri G. and Ann, Phoebe and Ma, Liang and Nagler, Cathryn R. and Ismagilov, Rustem F. and Mazmanian, Sarkis K. and Hsiao, Elaine Y. (2015)Indigenous Bacteria from the Gut Microbiota Regulate Host Serotonin Biosynthesis. Cell, 161 (2). pp. 264–276. ISSN 0092–8674. PMCID PMC4393509. http://resolver.caltech.edu/CaltechAUTHORS:20150409-093248232
Mendels J, Stinnett JL, Burns D, Frazer A. Amine precursors and depression. Arch Gen Psychiatry. 1975 Jan;32(1):22–30.
Yoichiro Takayanagi, MD, PhD, Adam P. Spira, PhD, O. Joseph Bienvenu, MD, PhD, Rebecca S. Hock, PhD, Michelle C. Carras, BA, William W. Eaton, PhD, and Ramin Mojtabai, MD, PhD, MPH. Antidepressant Use and Lifetime History of Mental Disorders in a Community Sample: Results from the Baltimore Epidemiologic Catchment Area Study. J Clin Psychiatry. 2015 Jan; 76(1): 40–44. doi: 10.4088/JCP.13m08824
Gerber PE, Lynd, LD. Selective serotonin-reuptake inhibitor-induced movement disorders. Ann Pharmacother. 1998 Jun;32(6):692–8.
Cartwright, C., Gibson, K., Read, J., Cowan, O., & Dehar, T. (2016). Long-term antidepressant use: patient perspectives of benefits and adverse effects. Patient Preference and Adherence, 10, 1401–1407. http://doi.org/10.2147/PPA.S110632
Pasco JA, Nicholson GC, Williams LJ, Jacka FN, Henry MJ, Kotowicz MA, Schneider HG, Leonard BE, Berk M. Association of high-sensitivity C-reactive protein with de novo major depression. Br J Psychiatry. 2010 Nov;197(5):372–7. doi: 10.1192/bjp.bp.109.076430.
Dowlati Y, Herrmann N, Swardfager W, Liu H, Sham L, Reim EK, Lanctôt KL. A meta-analysis of cytokines in major depression. Biol Psychiatry. 2010 Mar 1;67(5):446–57. doi: 10.1016/j.biopsych.2009.09.033. Epub 2009 Dec 16.
Maes M. Evidence for an immune response in major depression: a review and hypothesis. Prog Neuropsychopharmacol Biol Psychiatry. 1995 Jan;19(1):11–38.
Andrew C. Butler, Jason E. Chapman, Evan M.Forman, Aaron T.Beck. The empirical status of cognitive-behavioral therapy: A review of meta-analyses. Clinical Psychology Review. Volume 26, Issue 1, January 2006, Pages 17–31