Depression is a state of low mood that can persist for weeks or months.^[1] The symptoms of depression interfere with daily life and are often present during adolescence and young adulthood but may not be diagnosed until adulthood. As of 2019, The National Center for Health Statistics reports that 4.7% of U.S. adults over 18 years of age have regular feelings of depression.

The symptoms of depression vary widely, such as sleeping too much or too little. This is one reason why diagnosing depression can be a challenge. Other symptoms include lost interest in favorite activities, feeling hopeless, and under-or overeating.^[1] Symptoms may also vary by sex. For example, men with depression report higher rates of anger, aggression, substance use, and risk-taking compared to women.^[2]

Depression is diagnosed by a healthcare provider who usually uses questionnaires that assess symptom severity. For more information on diagnosing depression, please refer to the American Psychiatric Association.^[3]

Today, antidepressants (chiefly SSRIs and SNRIs) are still the first-line treatment for depression, but their effects vary across individuals, so one may need to try different antidepressants to find the correct one.^[1] Talk therapy is usually used in conjunction with antidepressants. If antidepressants fail to improve symptoms, brain stimulation therapies such as electroconvulsive therapy and transcranial magnetic stimulation can be effective tools for medication-resistant depression.^[4]

It appears that a Mediterranean diet or a diet consisting of foods with a low Dietary Inflammatory Index (DII) has been associated with a reduced risk of depression.^[5] However, more research is needed before a specific diet can be recommended. With that being said, current research suggests that improving one's diet by replacing "junk" foods with nutrient-dense, higher fiber foods, such as vegetables, fruits, whole grains, and nuts reduce the risk and symptoms of depression.^[6]

If you are using an antidepressant, consult your physician before taking any supplement, as cases of harmful interactions between certain supplements and antidepressants have been reported (e.g., between S-Adenosyl methionine and clomipramine^[7]).

With that in mind, several supplements and herbal remedies have been examined for depression including fish oil, saffron, curcumin, and zinc.

St. John's wort (Hypericum perforatum, or HP) has shown promise as an effective treatment for mild-to-moderate depression. Several studies have investigated its clinical impact by comparing the Hamilton Depression Rating Scale (HAMD) scores of people taking HP with those of people taking a placebo or traditional antidepressant medications. Some of these studies found that HP extracts have similar antidepressant properties and remission rate to serotonin reuptake inhibitors (SSRIs), with a lower rate of treatment discontinuation due to side effects.^[8][9][10] When compared to tricyclic antidepressants (TCAs), HP appears to cause fewer side effects and have lower dropout rates.^[10] However, it’s important to note that St. John’s Wort can adversely interact with many pharmaceuticals, including some antidepressants.^[8][11][12]

Although alternative treatments such as acupuncture, herbal medicines, and meditation are commonly used for depression, it is not recommended to use alternative medical treatments without seeking approval from a healthcare professional.

The causes of depression are complex, including prenatal factors, genetics, environment, biology, age, and sociocultural and psychological factors.^[13]