Is Depression A Mental Illness? Exploring The Medical Perspective

Medically reviewed by Laura Angers Maddox, NCC, LPC
Updated April 17, 2024by BetterHelp Editorial Team
Content warning: Please be advised, the below article might mention substance use-related topics that could be triggering to the reader. If you or someone you love is struggling with substance use, contact SAMHSA’s National Helpline at 1-800-662-HELP (4357). Support is available 24/7. Please see our Get Help Now page for more immediate resources.

Numerous reputable medical and mental health professional sources agree that depression is a severe mental illness that can cause substantial distress and disturbance in a person’s life and functionality. Read on to explore the medical perspective of depression and how it can affect the way someone thinks, acts, and feels. 

Do you know depression’s physical, mental, and emotional impact?

What is mental illness?

According to researchers at the American Psychiatric Association, mental illnesses are health conditions that involve changes to a person’s actions, thoughts, or emotions. Mental health conditions are generally associated with cognitive, emotional, or physical disruption and distress. The organization said approximately 19% of American adults experience a form of mental illness. 

Exploring the medical perspective of depression

Depression is a mood disorder that can severely impact the ability to function in multiple areas of daily life, such as work, school, or relationships. The condition can alter how a person thinks, feels, and behaves, often leading to further emotional and physical issues.

“For many people with depression, symptoms usually are severe enough to cause noticeable problems in day-to-day activities, such as work, school, social activities or relationships with others. Some people may feel generally miserable or unhappy without really knowing why.” — The Mayo Clinic

Recognizing depression signs

Researchers at the National Institute of Mental Health discussed common symptoms generally seen in most people with depression. However, it can be important to note that depression can look different in everyone. 

Common depression symptoms include:

  • Persistent moods of sadness, anxiety, emptiness, or hopelessness
  • Irritability, restlessness, or frustration, often over insignificant issues
  • Fixating on past mistakes, misplaced guilt, or feelings of worthlessness
  • Slowed speech, movements, and thoughts
  • Anhedonia—Loss or decrease of interest in or pleasure from previously favored activities
  • Social isolation
  • Drastic shifts in eating and sleep habits
  • Intense, persistent fatigue 
  • Feeling the sadness will last forever, so there is no point in treatment
  • Unexplained physical pain with no obvious cause—headache, stomachache, or muscle tension 
  • Difficulty thinking, focusing, or making decisions
  • Suicidal thoughts or actions—This requires immediate treatment. 

If you or a loved one are experiencing suicidal thoughts, seek help immediately. The National Suicide Prevention Lifeline can be reached at 988 and is available 24/7.


Overview of various mood disorders

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, lists several mood disorder classifications to help explain how people experience depression. 

Major depressive disorder

People who experience intense depression symptoms—such as loss of interest in previously favored activities, social withdrawal, and unhappy mood—for more than two weeks, causing severe functional impairment in multiple areas, may have major depressive disorder

Bipolar disorder

Previously called manic depression, bipolar disorder is characterized by cycling between overly-energized periods of extreme mood and behavioral symptoms called mania and extended depressive periods. Mania can cause severe impairment and induce psychosis in critical cases. 

Seasonal affective disorder

Many people experience depression symptoms with season changes, typically with summer and winter weather shifts. Seasonal affective disorder typically begins in late fall or early winter, lingering until late spring or early summer. 

Persistent depressive disorder

While depression is often severe for many patients, some experience low-level symptoms for much longer periods. Persistent depressive disorder, also called dysthymia, typically lingers for at least two years, influencing mood and behavior without causing drastic interference with functional ability. 

Postpartum depressive disorder

Parents or caregivers welcoming a child to their home after birth, fostering, or adoption can sometimes experience depression symptoms, intrusive thoughts, and radical mood swings. Postpartum depression should be addressed by a professional if it persists longer than two weeks or causes thoughts of harm to yourself or your baby.  

Treatments for depression

Generally, the most effective treatments for depression involve psychotherapy, life changes, adaptive coping skills, and medication. 


Depending on a person’s situation, depression symptoms, and neurochemistry, medication may be a vital part of a comprehensive treatment plan. Mental healthcare providers typically use several classes of medicine for depression. 

  • Selective serotonin reuptake inhibitors (SSRIs)
  • Monoamine oxidase inhibitors (MAOIs)
  • Serotonin-norepinephrine reuptake inhibitors (SNRIs)
  • Atypical antidepressants
  • Tricyclic antidepressants
  • Other medications like antipsychotics and mood stabilizers
Do you know depression’s physical, mental, and emotional impact?


Cognitive behavioral therapy (CBT) centers on helping patients identify harmful behaviors and thought patterns so they can consciously shift them toward healthier habits. CBT uses the connection between the way someone thinks and how they feel to reshape cognitive processes. Depression tends to alter a person’s thinking, and this therapeutic approach is particularly effective because it offers a way to think "around" the disorder to minimize its impact. 

Dialectical behavioral therapy (DBT) is a subset of CBT focused on acknowledging and accepting maladaptive behaviors and thoughts. By validating the patient's emotions and experiences, therapists offer guidance to process negative feelings, develop healthy ways to cope with stress and depression symptoms, and improve communication with friends or loved ones. 

Psychodynamic therapy analyzes unresolved conflicts in the patient’s history, often from childhood, and how they affect current thinking and behavior patterns. This therapy is often a long-term treatment that helps people develop emotional awareness and control skills.  

Interpersonal therapy helps patients examine the close relationships in their lives, identify the different roles people play, and find practical, balanced ways to resolve conflicts that may contribute to depression symptoms. This therapy is often short-term. 

"During psychotherapy, a person with depression talks to a licensed and trained mental healthcare professional who helps the person identify and work through the factors that may be triggering the depression… Taking care of the psychological and psychosocial aspects of depression are just as important as treating its medical cause." — The Cleveland Clinic 

The effects of untreated depression

If left untreated, depression can be deadly. In addition to the symptoms of depression themselves, many people experience cumulative effects as the condition persists. 


Suicidal thoughts and actions are often a symptom of depression. According to a recent study, the risk of suicide among people with depression is between 5% and 8%, while researchers of a 2018 study put that rate at 32%. 

If you are experiencing suicidal thoughts or urges, call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) or text 988 to talk to someone over SMS. Support is available 24/7. If you are experiencing trauma, support is available. Please see our Get Help Now page for more resources.

Related illnesses

Untreated depression can increase the risk of heart disease, Alzheimer's disease, diabetes, infections, and autoimmune disorders—or make their effects more pronounced.

Relationship troubles

When depression influences a person, it can make them withdraw from the people they're closest to, which can cause problems in those relationships. 

Physical health issues

  • Chronic pain or inflammation
  • Frequent headaches or migraines
  • Muscle cramps
  • Stomach problems, constipation, or diarrhea
  • Nausea or vomiting
  • Chronic fatigue, even after rest
  • Weight changes
  • Sleep disorders

Alcohol and substance use disorders

When left untreated, depression can alter a person’s thought patterns, putting them at a higher risk for alcohol and substance use disorders. 

If you are struggling with substance use, contact the SAMHSA National Helpline at (800) 662-4357 to receive support and resources. Support is available 24/7.

When to seek professional help

People are advised to seek help from a medical or mental healthcare professional if they experience depression symptoms for two weeks or more, have substantial difficulty functioning in one or more areas of daily life, or are concerned they may hurt themselves or someone else. 

How therapy can help treat depression

Psychotherapy is accepted in the medical community as the most effective treatment for mood disorders like depression. Many find that working with a licensed therapist online through a virtual therapy platform such as BetterHelp—or for children from 12 to 19—TeenCounseling, offers professional support and guidance to build an array of practical coping and communication skills. Online therapy is typically less expensive, has shorter wait times, and makes mental healthcare accessible to people who previously had no options. 

Online therapy offers similar results to treatment in the traditional face-to-face setting. According to a recent study, patients with no therapy experience showed a greater reduction in depression symptoms, but all participants saw a significant symptom severity decline. Many patients said the extra physical distance allowed by teletherapy made discussing personal details with a therapist easier. Others said the convenience of attending therapy from home was a considerable draw toward online treatment. The effectiveness and duration of therapeutic outcomes are increased with the number of therapy sessions and the level of trust between the patient and therapist.


Depression is a serious medical issue that can substantially affect your thoughts, behaviors, and emotions. From a medical standpoint, depression is a mental health condition that can cause intense emotional distress and interfere with a person’s ability to function in many areas. The information provided in this article offers a medically verified overview of depression and how therapy can help minimize its effects on someone’s life.
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