Depression: Signs, Symptoms and Treatment

what is depression

What Is Depression?

Next to anxiety, depression is the most common mental health condition in the United States, affecting over 14 million American adults every year, or about seven percent of the population. Depression is the leading cause of disability in the U.S. for people aged 15 to 44 years old.

Despite its overwhelming prevalence and significant public health impact, depression is still poorly understood by the majority of American citizens. From its colloquial use to refer to the feeling caused by any number of daily disappointments, to the mislabeling of normal, transient stress reactions as pathological depression, people widely think of depression as any instance of intense sadness. However, there is much more to the condition then its hallmark symptom of depressed mood.

Types of Depression

Depression can refer to specific psychiatric disorders like major depressive disorder or to a symptom of several mood disorders. The mood disorders listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM), the primary reference guide for psychiatric diagnoses, are:

  • Major Depressive Episode
  • Major Depressive Disorder
  • Persistent Depressive Disorder (Dysthymia)
  • Bipolar I Disorder
  • Bipolar II Disorder
  • Cyclothymic Disorder
  • The first three of these disorders are defined by persistent depressed mood, while the rest feature alternating depressive and elevated mood episodes. This is why you might have read specific information about “bipolar depression”—depressive episodes are treated differently when they arise in the course of bipolar disorder. [Note to Bart: maybe a good idea to link to my/your bipolar disorder article here?]

How Is Depression Diagnosed?

Early neurochemical theories of depression attributed its cause to the reduced availability of serotonin in the brain. This was reinforced by the efficacy of a class of antidepressant drugs called selective serotonin reuptake inhibitors (SSRIs). This theory is being revised as brain imaging research continues. Currently, people believe SSRIs work not by simply increasing serotonin levels, but by helping the brain build new connections and nerve cells in affected brain regions.

Regardless of its exact nature, the same brain activity that causes depressed mood causes a host of other effects. To be diagnosed with a major depressive episode, a person must have more than just depressed mood, with five or more of the following symptoms occurring in the same two-week period:

  • Daily depressed mood
  • Fatigue or loss of energy nearly every day
  • Frequent sleep disruption (insomnia or hypersomnia)
  • Significant weight loss when not dieting or weight gain
  • Diminished ability to think or concentrate, or indecisiveness
  • Restlessness or lethargy (psychomotor agitation or retardation)
  • Near-daily feelings of worthlessness or excessive or inappropriate guilt
  • Consistently diminished interest or pleasure in most activities (anhedonia)
  • Recurrent thoughts of death, recurrent suicidal ideation with or without a plan, or a suicide attempt

At last one of the symptoms must be depressed mood or anhedonia, which are considered the main clinical signifiers of depression.

As these symptoms show, depression not only involves an increased focus on negative thoughts and events, but a loss of mental and physical energy. This is why telling depressed people to “go out and have fun or “do more of what you enjoy” isn’t good advice. People with depression find it hard to muster the energy for these activities, and even when they can, they are less able to experience pleasure from doing them.

What Causes Depression?

There is no single cause of depression. People who experience a change in brain chemistry and function can become depressed even when things in their lives are going well. On the other hand, people can develop clinical depression in response to events or activities that affect their sense of hope. Sometimes, external activities that directly change the brain may be the cause.

For example, it’s possible to develop substance-induced depression due to the way drugs affect brain chemistry. It’s also possible for prolonged hopelessness from job loss or bereavement to cause changes in the brain that lead to depression. Regardless of the cause, the treatment for depression is the same. Because both internal and external factors need to be addressed, a combination of medication and therapy is the most common approach to treating depression.

Medication for Depression

Antidepressant medications aren’t right for everyone. However, they are safe for most people who are interested in trying them. Perhaps more than any other class of psychiatric drugs, they are unlikely to interfere with the treatment of co-occurring disorders, including substance use disorders.

Currently, the most commonly prescribed antidepressant medications are SSRIs, which were first developed and prescribed in the mid-to-late 1980s. Popular SSRIs include:

  • Fluoxetine (Prozac)
  • Paroxetine (Paxil)
  • Sertraline (Zoloft)
  • Citalopram (Celexa)
  • Escitalopram (Lexapro)

Most of their side effects are relatively mild. Those of greatest concern are sleep disruptions, which can contraindicate these medications for people with pre-existing sleep disorders; and sexual side effects, which significantly impact quality of life when they arise in a more severe form. In many cases, these side effects are mild or do not arise at all.

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are a newer class of antidepressant. Depending on differences that should be evaluated by a qualified physician, these may be more effective and have fewer side effects for some people. In general, they work in a similar way as SSRIs and have similar mild side effects. These include:

  • Duloxetine (Cymbalta)
  • Venlafaxine (Effexor)
  • Desvenlafaxine (Pristiq)

Another popular antidepressant that does not fit into either of these classes of drugs is bupropion (Wellbutrin). The way Wellbutrin works is not fully understood, but it is thought to affect dopamine and norepinephrine. In addition to being prescribed as an antidepressant, it is frequently prescribed as a smoking cessation aid. It has also been used to treat cravings for other stimulant drugs, including cocaine and methamphetamine, to varying degrees of success.

Therapy for Depression

As widely as antidepressants are prescribed, and as much as they have proven to be an important and effective tool in the treatment of depression, psychotherapy remains the gold standard for helping people recover from depression. Research shows that a combination of therapy and medication is far more effective in treating depression than medication alone.

The term “psychotherapy” refers to any form of “talk therapy” in which a person talks to a therapist about their problems. Some styles of therapy focus more on pragmatic goals and problem-solving, while others are more open-ended and target subtler emotional causes of distress. The therapeutic relationship is a cornerstone of every type of therapy.

Cognitive behavioral therapy (CBT) is one of the most common and proven interventions for depression. This technique targets symptoms and incorporates behavioral changes to rapidly improve them. Specifically, CBT uses the relationship between thinking, emotion, and behavior to address all three at once.

Thinking is a primary trigger of feeling and action and is easier to directly change than they are. In CBT, a therapist helps a client examine their thoughts and identify cognitive distortions and irrational beliefs that drive negative emotion and self-destructive behavior. For example, a CBT client might believe they are not a good person and don’t deserve to be happy. Their therapist will explore these beliefs and help the client find evidence that they aren’t true.

Psychodynamic psychotherapy is an older style of therapy that has fallen out of vogue, though recent research has shown it is just as effective as CBT for the treatment of depression. Based on theories of early psychoanalysts like Sigmund Freud and Carl Jung, psychodynamic therapy focuses on helping clients gain insight into the origins of painful thoughts and feelings. People who practice this style of therapy believe these insights and the process of making previously unconscious material conscious facilitates healing on a deeper level.

In psychodynamic psychotherapy, therapists explore clients’ childhood memories and stories to help them discover why they think, feel, and act as they do as adults. For example, a therapist might help a client identify their father’s verbal abuse as one of the causes of their depression and negative self-beliefs. As a client realizes that the things their father said weren’t true, and were rooted in his own issues, they become freer to believe and act differently as an adult.

Depression and Addiction

The statistics show a strong relationship between depression and addiction: almost a third of people with a mood disorder have a co-occurring substance use disorder. Nearly one-fifth of people with a lifetime history of major depressive disorder have a substance use disorder. This means that people who are depressed have higher rates of substance abuse than the general population and people with substance use disorders have higher rates of depression.

There are many possible reasons for this co-occurrence. There may be shared biological, social, and environmental factors, or one disorder may drive the other. Trauma can cause depressed mood and drive the development of substance use disorders; people may use substances to try to feel better when they’re depressed; and substance use can trigger neurochemical changes that lead to depression.

Comorbid disorders are harder to treat. Improvement in one condition can lead to setbacks in the other. For example, gaining a period of abstinence from substance use might temporarily have a negative impact on mood. Processing difficult material in mental health treatment may trigger substance use cravings or relapse.

For this reason, treatment of co-occurring disorders should be integrated. When people can participate in substance abuse treatment groups, individual psychotherapy, and medication management at the same organization, or at least at organizations that communicate closely with one another, they recover more quickly from co-occurring disorders. This is because their treating professionals can coordinate their interventions based on the information they receive from one another and tailor them as needed.


Depression is a widely discussed but poorly understood disorder that affects a significant percentage of the American population. Far from just a change in mood, it is a holistic change in brain functioning that results in a loss of mental and physical energy. Fortunately, there are many effective treatments available for depression, including medication, therapy, and integrated treatment for people with co-occurring mood and substance use disorders.

If you or someone you love are suffering from depression, reach out. This illness can make you feel alone, but you are not. Many people have shared your experience and can help you find a way out of the maze of depression. Your journey to recovery can begin today.


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