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Mental Illness vs Mental Disorder: What Is The Difference?

Key Points

  • “Mental illness” and “mental disorder” are often used interchangeably but can be used more accurately to describe different concepts.
  • Mental disorder is used in clinical settings to describe a specific set of symptoms or a diagnosis.
  • Mental illness is used more broadly and conversationally to describe health and includes disorders of anxiety, depression, trauma, and others.

Is There a Difference Between Mental Illness and Mental Disorder?

“Mental illness” and “mental disorder” are terms often used interchangeably by medical and mental health professionals. They describe a similar set of conditions but are not the same. As professionals and laypeople alike continually pursue the use of the most up-to-date terminology, it is essential to be able to distinguish between the two.

How Mental Illness and Mental Disorder Are Similar

Both terms refer to mental health conditions that impact a person’s ability to engage in life meaningfully. Individuals may have a mental health issue if their thoughts, emotions, behavior, and overall mental well-being affect their ability to do the following:

  • Engage in productive activities (such as work, school, and household tasks)
  • Have sustained and healthy relationships
  • Be able to adapt to change and utilize healthy coping skills

What is a Mental Disorder?

According to the National Institutes of Health (NIH), a mental disorder is “a disturbance of normal functioning of the mind or body.” Genetic factors, diseases, or trauma can cause mental disorders.[1]

“Mental disorder” is a term typically used in the context of mental health diagnoses and psychiatry. Mental health disorders are classified and diagnosed based on the established criteria provided in the official Diagnostic and Statistical Manual of Mental Disorders (DSM-5). These criteria help mental health professionals determine if an individual’s symptoms align with a specific mental disorder.

Examples of specific mental health disorders are Generalized Anxiety Disorder (GAD) and Major Depressive Disorder.

The term “mental disorder” has been used less frequently in everyday conversation to describe mental health issues in general, primarily because “disorder” has a negative connotation. “Illness” seems to encourage people to imagine an actual person struggling with a medical condition rather than just a set of symptoms.

What is Mental Illness?

“Mental illness” is a broader and more general term encompassing many conditions impacting a person’s mental health. It is a term often used in a conversational or everyday context to describe conditions that affect a person’s mental and emotional state. Unlike the term “mental disorder,” the term “illness” indicates mental health conditions affect more than just the mind.

Today, mental illness is used more widely to describe a person’s mental well-being. The term “mental illness” emphasizes that these conditions can affect emotion, thinking, or behavior (or a combination of these). Mental illnesses can be associated with specific sources of distress or general problems functioning in social, work, or relationships.

Additionally, mental illness is treatable. Most individuals who suffer from a mental illness continue to function at typical levels in their daily lives. Many people seeking treatment and prioritizing their mental well-being can move forward better than they had before.

Types of Mental Illness

Mental illness comes in many forms, each with its own symptoms and treatment plans. Mental illness is broken down into categories of specific disorder types, including the following:[2]

Anxiety Disorders

Anxiety is one of the most common types of mental illness. Anxiety can affect your sleep, concentration, and completing simple tasks. Typical symptoms include feeling worried and excessively nervous or with a tendency toward panic.

Mood Disorders

Mood disorders affect an individual’s emotional state. Typical examples are depression, bipolar disorder, and seasonal affective disorder.

Personality Disorders

Personality disorders involve unpredictable thinking and behavior. Individuals with personality disorders may experience extreme emotions and difficulty maintaining healthy relationships.

Psychotic Disorders

Psychotic disorders impact a person’s relationship to reality. Common symptoms are changes in behavior and cognition. A person with a psychotic disorder experiences delusions and hallucinations that significantly affect functioning if left untreated.

Substance Abuse Disorders

Addiction and abuse of substances such as drugs and alcohol can directly affect mental health. The use of drugs over the long term can significantly impact brain function and relationships, as well as a person’s ability to maintain employment and other productive activities.

Eating Disorders

Eating disorders are complex. They can develop because people are attempting to cope with overwhelming and painful emotions by controlling their food intake. These conditions can cause severe emotional and physical problems without treatment. Anorexia, bulimia, and binge eating disorder are all examples of common eating disorders.

Trauma-Related Disorders

Post-traumatic stress disorder (PTSD) and acute stress disorder are trauma-related disorders that are born of traumatic or harmful experiences. Highly stressful events and ongoing trauma exposure can cause mental health illnesses related to a person’s experiences.

Seeking Help Begins Healing

Everyone has days where they feel a little down or stressed. If you experience symptoms of mental health issues frequently, it’s worth pursuing care for yourself. Untreated mental illnesses can worsen over time. This will undoubtedly make it difficult for you to function in your daily life.

Signs and symptoms of mental health struggles vary for each individual. Symptoms that may indicate you are struggling with a mental illness include the following:

  • Struggling to complete responsibilities due to lacking motivation or feeling easily overwhelmed
  • Feeling worthless or guilty
  • Avoiding friends and family
  • Having significant struggles with relationships
  • Losing interest in hobbies and feeling apathetic
  • Experiencing panic or anxiety attacks
  • Feeling overwhelmed with stress that you cannot resolve on your own
  • Noticing changes in appetite or weight that are not due to changes in exercise or diet
  • Feeling more emotionally reactive or irritable than usual
  • Having thoughts of self-harm or suicide
  • Experiencing auditory, tactile, or visual hallucinations or feeling paranoid

While not an exhaustive list, the above signs of mental illness could serve as a “check engine” light for you to pursue the help you need. If you feel that any of these symptoms apply to you, consider seeking support.

Frequently Asked Questions About Mental Illness vs. Mental Disorder

What is the most common mental health disorder?

Based on data from the American Psychological Association, anxiety disorders were the mental disorders most frequently treated, closely followed by depressive and trauma-related disorders.[3] Because this report is about individuals seeking treatment, however, it may not accurately reflect the actual prevalence of these disorders.

Does mental illness affect social life?

Poor mental health issues, regardless of severity, influence relationships. Depending on your symptoms, relating to friends, spouses, family members, and co-workers can be challenging.

However, while mental illness can impact social life negatively, individuals with mental health issues can still maintain meaningful relationships and engage in social activities. Professional help, a supportive social network, and self-care strategies can all play crucial roles in helping individuals navigate their social lives.

How does mental illness impact relationships?

A mental illness does not exclude you from having an enjoyable relationship with the right support and understanding, but there are challenges. Mental illness can cause social isolation due to concerns about disclosing mental health struggles. Symptoms like irritability, mood swings, or emotional numbness can pose significant challenges to sustaining healthy connections. It can feel like no one understands, or you will burden a friend or family member with your problems. Additionally, a partner not struggling with mental health issues might feel unsure of how to help or incapable of providing support.

Hope Starts Here

Though the terms are similar, “mental illness” and “mental disorder” have separate uses and meanings. As times change and mental health feels less stigmatized, it’s vital to learn how to normalize and better support people with mental health concerns. By differentiating these terms, we are already better equipped.

When ongoing signs and symptoms of mental illness cause frequent stress, seeking professional support can help. You deserve support and understanding, and your concerns are valid


  1. NCBI. (2012). Information about Mental Illness and the Brain.; National Institutes of Health (US).
  2. World Health Organization. (2022). Mental disorders. World Health Organization.
  3. American Psychological Association. (2021). Mental disorders most frequently treated by psychologists. Monitor on Psychology.
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