Major depressive disorder (MDD) is one of the most common mental disorders in the United States. Nearly 7 percent of all adults experience MDD each year. MDD is also closely tied to other mental health conditions, including anxiety disorders, dysthymia, obsessive compulsive disorder (OCD), and eating disorders.

Anxiety Disorders

Research suggests that MDD and anxiety disorders occur together even more frequently than they do separately. As many as 60 percent of those with either MDD or an anxiety disorder are also diagnosed with the other condition.

Diagnosing either of these conditions separately can be difficult. This is partially because many of the symptoms associated with depression are the same for anxiety, but not all patients have the classic symptoms you might expect. These non-typical symptoms can include:

Talk to your doctor if you’re experiencing any of these symptoms. They can help you pinpoint what’s causing them and help you get treatment.

Obsessive Compulsive Disorder

About two thirds of those diagnosed with obsessive compulsive disorder (OCD) will experience at least one episode of MDD in their lifetime. Oftentimes, depression occurs after the appearance of OCD. This may suggest that depression could be the result of the continued distress caused by situations at work and home that are related to the symptoms of OCD.

Both OCD and depression have been found to involve a change in serotonin levels, suggesting that these two conditions are biochemically and psychologically related. Serotonin is a chemical in the body that helps regulate mood, sleep, memory, and certain behaviors.

MDD can interfere with different psychological treatments for OCD, including exposure and response prevention therapy. When your therapist is aware of your depression, psychotherapy can be tailored to treat the symptoms of both depression and OCD. In severe cases, your therapist may have to treat your MDD before they can start to address your OCD symptoms.

Fortunately, the medication used to treat MDD doesn’t have negative effects on OCD. Many of the medications prescribed for depression are selective serotonin reuptake inhibitors. These are antidepressants that also treat the symptoms of OCD.

Eating Disorders

Almost 50 percent of all individuals diagnosed with eating disorders also meet the criteria for depression. Eating disorders include:

Women are much more likely than men to develop an eating disorder: only 5 to 15 percent of those who have anorexia or bulimia are male.

Sometimes people with MMD self-medicate with food, which is why eating disorders are so closely tied with depression. Knowing whether MDD or the eating disorder came first is difficult. This is primarily because no two eating disorders are the same and no two individuals are the same.

Dysthymia

Dysthymia, or dysthymic disorder, is a type of depression marked by recurring symptoms of severe sadness and depression. These feelings are long term and last for at least six months. Up to 4 percent of the population has dysthymia.

Dysthymia is similar to MDD, but it’s lower in severity. Dysthymia is low-grade depression, while MDD is a more intense form of chronic depression. However, if left untreated, dysthymia can develop into a more serious form of depression.