What Is Major Depressive Disorder?

Major depressive disorder (MDD) is the clinical name given to the diagnosis of clinical depression or major depression as currently designated in the Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition (DSM-5).

This is the manual used by mental health professionals in the United States to diagnose psychological disorders, and it is published by the American Psychiatric Association (APA). This article will discuss MDD and its relationship to substance abuse as well as treatment options for both.


a man suffering from major depressive disorder

Having temporary and intermittent feelings of sadness, being down, feeling disappointment, etc., represents a normal part of human experience. In addition, individuals often become very saddened over certain events that happen to them, such as the death of a loved one, loss of a job, divorce, etc. Again, in the majority of cases, these represent normal experiences of living. While they may often be difficult and painful times for people, most people are able to negotiate these issues and are not diagnosed with a mental health disorder as a result of their reaction to them. Normal and expected variations in mood in response to life events typically do not result in psychopathology. MDD is a clinical diagnosis made when an individual’s experience of depression results in a number of severe emotional issues and functional impairments, and extends beyond what is considered to be the normal time period for these experiences.

The formal diagnosis of MDD is made based on a number of clinical diagnostic criteria. In order to receive a formal diagnosis of MDD, an individual must meet five (or more) of nine clinical diagnostic criteria. These behaviors or feelings also must have been present on a consistent basis for at least two weeks, and the behavior that person exhibits must result in serious distress or impairment in their functioning. In addition, the person’s presentation cannot be better explained by their use of drugs or medications, by some medical condition (e.g., a thyroid problem or head injury), and cannot be better explained by some other psychiatric/psychological disorder.

According to the DSM-5, the diagnostic criteria for MDD are (the person must meet a minimum of five over a two-week period):

  • The person presents with a dejected mood for the majority of the day.
  • The individual has feelings of extreme guilt or being worthless.
  • The person is very indecisive or has marked difficulty concentrating.
  • The person presents with an extreme loss of interest or is unable to feel pleasure in nearly every activity most of the day.
  • The person has experienced significant weight loss (or weight gain) or has a decrease (or increase) in appetite.
  • The person sleeps excessively (hypersomnia) or experiences an inability to go to sleep (insomnia).
  • The person has a significant loss of energy or feels significantly tired and fatigued.
  • The person displays significant psychomotor retardation (moving very slowly) or psychomotor agitation (marked irritability or restlessness).
  • The person has continual thoughts about death, self-harm, or has a plan to commit suicide.

The APA also allows for a number of different features to be diagnosed in depression, such as depression with anxious distress where an individual presents with an anxious type of depression; depression with atypical features where the individual may gain weight (as opposed to more typical weight loss), has increased appetite (as opposed to more typical decreased appetite) and sleeps excessively (where it is more typical for individuals with MDD to be unable to sleep); and other special presentations of the disorder.

Who Gets Diagnosed with MDD?

a woman suffering from major depressive disorder

MDD occurs in both men and women, across all ethnic groups, at all levels of social economic status, and across all age groups. Nonetheless, there are some individuals that are more prone to developing MDD. When discussing what types of variables lead to increased probability of developing a mental health disorder such as MDD, this is typically discussed in terms of risk factors. A risk factor represents a condition that results in an increased probability for an individual to develop some type of disease or disorder. These risk factors are not necessarily causes of the disorder; risk factors simply increase the likelihood that someone could develop the disorder or disease.

Risk factors associated with the development of MDD include:

  • Sex: Women are diagnosed with MDD at a rate of 2.5 times more often than males.
  • Heredity: A number of genetic associations have been identified as risk factors for the development of MDD. If a person has a relative, particularly a first-degree relative, who was diagnosed with MDD, this increases their risk to develop the disorder.
  • Stress and/or trauma: Individuals who experience major stressful events, particularly in childhood, are at risk to develop MDD. These stressful events can include physical or sexual abuse, loss of a loved one, poor parental practices, loss of occupation, etc.
  • Other mental health disorders: An existing diagnosis of another psychiatric disorder increases the risk to develop MDD.
  • Substance abuse or addiction: The presence of a substance abuse issue increases the risk to develop MDD.
  • Medical conditions: Individuals who are diagnosed with certain chronic medical conditions are at a risk to develop MDD. These include a number of conditions, including cardiovascular problems, cancer, stroke, HIV, chronic arthritis, etc.
  • Social economic status: Individuals from lower social economic status groups appear to be at a higher risk to develop MDD.

MDD and Substance Abuse

As mentioned above, any person who receives a diagnosis of a mental health disorder is also at risk to develop MDD. This includes being diagnosed with a substance use disorder (the clinical term used by the APA that includes both substance abuse and addiction). Likewise, individuals diagnosed with MDD are also at increased risk to develop a substance use disorder, indicating that the relationship between MDD and substance abuse is bidirectional. When individuals are diagnosed with a mental health disorder and a co-occurring or comorbid substance use disorder, the situation is commonly referred to as co-occurring disorders or a dual diagnosis. There is quite a body of empirical research investigating the rate of individuals diagnosed with MDD that also have co-occurring substance use disorders. As a general rule, it can be considered that at least one-third of individuals with MDD also have some co-occurring substance use disorder.

The particular type of substances that are abused in individuals with MDD can be quite variable. Most often, alcohol, prescription medications (most commonly, anti-anxiety medications or narcotic pain medications), marijuana, and cocaine are abused by those with MDD.

The relationship between MDD and substance abuse is such that it can occur in a number of different ways. Some individuals with MDD may resort to drug abuse to attempt to deal with their depression, while in other cases, individuals with substance use disorders become depressed because of the ramifications of their drug use. It may be that similar brain pathways shared by most mental health disorders lead to an increased risk of developing several related disorders. Because MDD and other mental health disorders share a number of similar neurobiological mechanisms, simply being diagnosed with either MDD or a substance use disorder may predispose a person to develop another type of mental health disorder.

How MDD Is Treated

There are number of treatment options to address MDD. Individuals who are diagnosed with co-occurring disorders that include MDD and a substance use disorder would need to have both disorders treated at the same time. Trying to address one disorder, such as addressing one’s alcohol abuse and ignoring MDD, will not be productive. There are number of different treatment options that include:

  • Medical management: There are a large number of potential medications that can be used in the treatment of MDD and in the treatment of issues with substance use disorders. They can be applied to the concurrent treatment of both MDD and a substance use disorder. Several classes of antidepressant medications now exist that are believed to be useful in the treatment of depression. These can also be useful in the treatment of certain issues with certain types of substance use disorders. There are also a number of different medications used in the treatment of substance use disorders that can assist with controlling withdrawal symptoms, cravings, and other issues that occur as part of recovery.For individuals who have very severe and treatment-resistant depression, the administration of electroconvulsive therapy (ECT) can sometimes be useful in alleviating very severe depressive symptoms. ECT continues to receive quite a bit of negative press from the media, and its depiction in films or on television is often inaccurate. The process of ECT has been refined and improved far beyond what individuals see in movies where patients are strapped down and practically electrocuted. The process is far more therapeutic. ECT is performed in a clinical environment by trained and licensed psychiatrists and other medical personnel. It is often used because other forms of treatment, including medical management and/or therapy, have been ineffective.
  • Counseling and therapy: Several empirically validated methods of therapy can be used in the treatment of MDD, substance use disorders, and co-occurring disorders. Typically, some form of Cognitive Behavioral Therapy is integrated into the treatment plan for these disorders, although other types of therapy may be useful as well. This type of therapy addresses the individual’s attitudes, thinking patterns, and belief system. Therapy can be administered on an individual basis, in groups, with one’s family members, or individuals can attend combinations of these.
  • Social support: A useful treatment mechanism is the use of the social support groups. These groups do not qualify as therapy groups, as they are not typically run by licensed therapists, but instead are organized and run by individuals who have issues with the types of disorders that the groups are designed to address. For example, the most famous social support group is the 12-Step group Alcoholics Anonymous, designed for support and treatment of alcoholism. Other relevant support groups include Depressed Anonymous, designed to address individuals diagnosed with MDD.
  • Lifestyle changes: Individuals with MDD can also benefit from positive changes in their lifestyle. These changes can include eating a healthier diet, engaging in an exercise program, practicing yoga, getting involved in meditation, and strengthening personal relationships. A number of positive lifestyle changes can change one’s outlook on life.