The Most Common Mental Health Diagnoses and Their Symptoms

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Navigating life with a mental illness can feel isolating and lonely at times. But the truth is, 1 in every 8 people in the world live with a mental disorder – you’re far from alone. These are the most common mental illnesses and what they tend to look like.

Keep in mind that everyone’s mental health is different. Two people may have the same diagnosis, but it might look completely different for each person. But knowing the most common mental disorders can help you feel a sense of community as you work toward a better, healthier life.


Anxiety is defined as excessive fear and worry and related behavioral disturbances. In order to become a disorder, these symptoms must be severe enough to cause significant distress or impair your functioning (getting in the way of everyday life).

There are lots of different anxiety disorders, including (but not limited to):

  • Generalized anxiety disorder
  • Panic disorder (panic attacks)
  • Social anxiety disorder (excessive fear and worry in social situations)
  • Phobias


The mental health condition known as depression is different from usual mood fluctuations and short-lived emotional responses to challenges in everyday life. In order for depression to be considered a disorder, a person must suffer from depressive episodes (periods of feeling sad, irritable, or empty) and have a loss of pleasure in things they used to enjoy most of the day, nearly every day, for at least 2 weeks.

The severity of depression ranges from mild to severe. Symptoms include:

  • Poor concentration
  • Feeling excessively guilty or worthless
  • Thinking about dying or suicide
  • Trouble sleeping
  • Changes in appetite
  • Feeling lethargic or tired


ADHD, one of the most common neurodevelopmental disorders, usually first appears in childhood (but often lasts into adulthood as well). There are three types of ADHD: inattentive type, hyperactive type, and combination type.

Symptoms of ADHD include:

  • Trouble paying attention
  • Impulse control issues
  • Hyperactivity
  • Frequent daydreaming
  • Forgetting or losing things a lot

Eating Disorders

The many types of eating disorders (such as anorexia and bulimia) are characterized by abnormal eating, preoccupation with food, and prominent concerns about body weight and shape. Eating disorders can cause significant risk or damage to a person’s physical health, distressing emotions, and/or significant impairment in carrying out the regular demands of daily life.

Post-Traumatic Stress Disorder (PTSD)

PTSD can develop after a person is exposed to extremely threatening or traumatic events, which is why it’s prevalent in conflict-affected settings or populations who are predisposed to experiencing trauma. PTSD can be caused by a single event or by several events.

PTSD can involve:

  • Re-experiencing the traumatic event(s) through visual or emotional flashbacks
  • Avoiding thoughts or memories of the event(s)
  • Consistently feeling a heightened level of danger or threat

If any of these mental illnesses sound like they might apply to you, know you’re not alone! You can find support by seeking help and finding a supportive community of mental health care professionals and other people navigating similar symptoms as yourself.

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