The relationship between substance use and depression is bi-directional, meaning that either one can lead to the manifestation of the other. About one-third of people diagnosed with major depression also have a drinking problem, for instance. 

Sometimes a person's history indicates which came first, but it may be unclear. Regardless of whether depression or substance use disorder is the initial problem, effective treatment must focus on recovery from both at the same time. 

Self-Medicating With Drugs or Alcohol

People experiencing the symptoms of depression may turn to drugs or alcohol as a negative coping strategy or as to self-medicate. These substances can give a temporary high, which relieves depression. 

However, when the effects of the drugs or alcohol wear off, you are left feeling depressed again. That begins a cycle in which drugs or alcohol use increases to keep symptoms of depression at bay, especially if this person also develops a tolerance to the drug.

Some substances have a depressive effect, even in individuals who did not show symptoms of depression before their use. The primary impact of substances known as depressants like alcohol is a quieting of the central nervous system, leading to difficulty concentrating, lethargy, and other symptoms commonly seen in people experiencing depression. Benzodiazepines, barbiturates, and hypnotics are also examples of depressants. 

Underlying Causes of Both Depression and Substance Use Disorder

In addition to depression and substance use disorder having a bi-directional relationship, they share some of the same underlying causes. Individuals with the following risk factors have an increased chance of developing either (or both) depression and substance use disorder:

  • Low serotonin levels in the brain

  • Low dopamine levels in the brain

  • A genetic predisposition for depression or substance use disorder

  • Childhood stress and trauma

  • Chronic stress

These factors don't guarantee that anyone with a substance use disorder will experience depression, but they do represent common traits seen in individuals experiencing one or both of these disorders.

Recovering from Co-Occurring Disorders

When depression and substance use disorder are co-occurring, someone has a diagnosis for both conditions (also called dual diagnosis). Treatment for both must happen at the same time. If you address them one at a time, the risk for relapse increases. 

Treating depression without treating substance use disorder could cause depression symptoms to reoccur if you use drugs or drink alcohol again. On the other hand, treating substance use disorder without treating depression could lead to self-medicating with drugs and alcohol during a particularly low period in their depression.

For long-lasting results, it's best to tackle both depression and substance use disorder together. A multi-faceted treatment plan gives you the tools necessary to end or reduce dependence on substances while also improving overall mental, emotional, and physical health.