How to Diagnose Mental Illness

Want to know how to diagnose mental illness? Read this. Also discover why a mental illness diagnosis is important.

It's common to wonder how to diagnose mental illness. How do doctors tell the difference between extreme reactions to stress and similar thoughts, feelings, and behaviors related to mental illness? In fact, you may be wondering, "What mental illness do I have?" To understand how to diagnose a mental illness, it's helpful to examine what a diagnosis is.

What a Mental Illness Diagnosis Does

Understandably, many people are anxious about receiving a diagnosis of mental illness. Given the stigma surrounding mental illness, it's not unusual for people to have trepidation about being diagnosed and from then on living with a label. (Read: Adapting to Living with a Psychological Disorder)

That's a very real fear, but understanding mental illness diagnosis can help put people at ease. First and foremost, to diagnose mental illness is to describe someone's mental illness symptoms and nothing more. Diagnosis isn't a judgment about a person and who he or she is; it's a description of what he or she is experiencing. It's like how a diagnosis of asthma simply means that a person has respiratory problems; it doesn't mean he or she is weak or out of shape.

Beyond describing symptoms, a mental illness diagnosis does other helpful things. A diagnosis

  • names the problem, which is important because naming and defining a problem is the first step toward treating it
  • describes specific behaviors, thoughts, and feelings related to a specific illness
  • provides a common language and set of terminology understood by all mental health care professionals so that they can communicate with each other efficiently to provide the best possible care for the client
  • gives people an indication of prognosis (the expected course of and recovery from the mental disorder)
  • leads to guidelines for treatment and management

How to Diagnose Mental Illness: Symptoms

Mental illness symptoms are presented for every psychiatric disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) (American Psychiatric Association, 2013). The DSM-5 is the accepted authority in the U.S. on psychiatric disorders. The symptoms of mental illness are a part of every disorder's diagnostic criteria and form the foundation for a mental illness diagnosis.

Even using the symptoms, to diagnose mental illness isn't simple. It's not a matter of running down a checklist and arriving at a solid conclusion in a single office visit. That's because while books are black-and-white, people are not. A careful study of the symptoms of each mental illness reveals that there is a great deal of overlap from one disorder to the next. Further, people are constantly in a state of flux. We change, and mental illness signs and symptoms change with us. There are other aspects of life which complicate signs and symptoms of mental illness.

So the question of how to diagnose mental illness isn't always straightforward. It does, however, have an answer.

How to Diagnosis a Mental Illness: Process

When someone goes to a clinician for help with mental illness symptoms, the clinician needs to determine exactly what is wrong. Formal assessments and mental illness diagnosis tests are typically conducted, but other techniques are used as well.

  • using the diagnostic criteria outlined in the DSM-5 to hone in on what's going on with someone based on signs and symptoms
  • discovering the severity of the disorder; is it mild, moderate, or severe;
  • as part of severity, examining distress and disability; what life areas are affected by the symptoms (relationships, school, work, leisure life, etc.)
  • inquiring about environmental influences that may play a factor in the current distress

Mental health professionals consider other factors as well as they diagnose a mental illness.

  • family traits
  • genetic factors
  • the person's temperament
  • symptoms similar to other illnesses
  • the person's history and course of the illness

A Mental Illness Diagnosis Is Complex But Worth It

Diagnosis is important because it helps people understand themselves. When someone learns about the disorder he has been diagnosed with, he can use the information to regain wellness. For example, knowing the symptoms and what they mean can help people stop criticizing themselves for their thoughts, feelings, and behavior. A diagnosis helps people separate who they truly are from the mental illness they have, and when they do that, they are on the road to recovery. How to diagnose a mental illness? It begins with a decision to see a mental health provider (I Need Mental Help: Where to Find Mental Health Help).

APA Reference
Peterson, T. (2019, October 23). How to Diagnose Mental Illness, HealthyPlace. Retrieved on 2024, July 16 from

Last Updated: October 23, 2019

Medically reviewed by Harry Croft, MD

More Info