Mental Health Conditions

What You'll Find Here

Mental health conditions are patterns of thinking, feeling and behaving that are persistent and significant enough to cause distress or interfere with daily life at home, work, school or in relationships. This page is an A–Z guide to mental health conditions, grouped into the major categories used in modern clinical practice, with links to in-depth, plain-language guides covering symptoms, causes and evidence-based treatment.

Mental health conditions are common, treatable and far more varied than many people realize. The World Health Organization's 2022 World Mental Health Report estimated that about one in eight people worldwide were living with a mental disorder in 2019, with anxiety and depression the most common. Conditions range from time-limited responses to stress to lifelong patterns that benefit from ongoing support. What unites them is that symptoms are persistent and disruptive enough to affect everyday functioning.

Clinicians organize these conditions into broad families based on their core features. Anxiety and obsessive-compulsive related disorders center on excessive fear, worry and intrusive thoughts. Mood disorders involve sustained disturbances of emotion, from depression to the highs and lows of bipolar disorder. Psychotic disorders are marked by a loss of contact with shared reality. Personality disorders describe enduring patterns of thinking and relating that cause distress. Neurodevelopmental conditions emerge early in life and shape attention, learning and social communication. There are also families for eating disorders, trauma- and stress-related conditions, somatic conditions, substance use disorders and neurocognitive disorders such as the dementias.

Diagnosis is made by qualified professionals using standardized criteria, most often the DSM-5-TR or the World Health Organization's ICD-11. These categories are a map, not a label that defines a person; many people experience more than one condition, and symptoms often overlap. The guides are designed for education and orientation, not self-diagnosis. If something here resonates with your experience, the most useful next step is to speak with a qualified professional who can offer a proper assessment.

Anxiety & OCD-Related Disorders

Conditions defined by excessive fear, worry, avoidance, and intrusive, repetitive thoughts or behaviors. Anxiety disorders are the most common group of mental health conditions. Start with anxiety disorders for an overview, then explore generalized anxiety disorder, panic disorder, social anxiety disorder and phobias. Obsessive-compulsive and related disorders, which DSM-5-TR places in a separate chapter, include OCD, hoarding disorder and body dysmorphic disorder.

Mood Disorders

Sustained disturbances of emotion, energy, and mood, from depression to the cycles of bipolar illness. Begin with depression, then read about persistent depressive disorder, a long-lasting form that is often missed, and bipolar disorder, which involves episodes of mania or hypomania. Related guides cover cyclothymic disorder, premenstrual dysphoric disorder and postpartum depression.

Psychotic Disorders

Conditions involving a loss of contact with shared reality, such as delusions or hallucinations. Psychosis explains these experiences in general, and schizophrenia is the best-known psychotic disorder. Related conditions include schizoaffective disorder and delusional disorder. Early assessment and treatment are associated with better outcomes.

Personality Disorders

Enduring patterns of thinking, feeling, and relating that differ markedly from expectations and cause distress. The personality disorders overview explains the DSM-5-TR clusters and the newer dimensional approach in ICD-11. The most researched condition is borderline personality disorder; other guides cover narcissistic, antisocial, avoidant and obsessive-compulsive personality disorders, among others.

Neurodevelopmental Disorders

Conditions that emerge early in development and shape attention, learning, communication, and behavior. Key guides include ADHD, ADHD in adults, the autism spectrum, specific learning disorders such as dyslexia, and Tourette syndrome. Many people see these conditions through the lens of neurodiversity. Childhood behavior conditions such as oppositional defiant disorder and conduct disorder are covered too.

Eating Disorders

Serious disturbances in eating behavior and related thoughts about food, weight, and body image. Eating disorders, including anorexia nervosa, bulimia nervosa and binge eating disorder, carry significant health risks, and anyone concerned should speak with a doctor promptly. Our educational guides cover related topics such as body image, emotional eating, pica and rumination disorder.

Trauma & Stress-Related Disorders

Conditions that develop in response to traumatic or highly stressful events and their aftermath. Start with trauma and PTSD, then read about post-traumatic stress disorder, complex PTSD, acute stress disorder and adjustment disorders. Dissociative conditions, such as depersonalization-derealization disorder and dissociative identity disorder, are often linked to trauma.

Somatic & Related Disorders

Conditions in which physical symptoms or health worries become a major source of distress. The general guide to health anxiety is a good starting point, followed by somatic symptom disorder, illness anxiety disorder, functional neurological (conversion) disorder and factitious disorder. Conditions at the boundary of mind and body, such as irritable bowel syndrome, show how closely psychological and physical health interact.

Substance Use Disorders

Patterns of substance use that lead to significant impairment, distress, or loss of control. For the science behind addiction, start with the psychology of addiction and addiction. Behavioral patterns with addiction-like features, such as gaming disorder and compulsive buying, are covered as well. Substance use problems are treatable, and a primary care doctor can be a confidential first point of contact.

Neurocognitive Disorders (Dementias)

Conditions involving a decline in memory, thinking, and reasoning, often associated with aging. Dementia provides an overview, with detailed guides to Alzheimer's disease, vascular dementia and Lewy body dementia. Mild cognitive impairment describes changes that are noticeable but not yet disabling, and delirium is a sudden, often reversible state of confusion that needs urgent medical attention.

Understanding Is the First Step

Learning about a condition can reduce fear and stigma and make support easier to seek. These guides are for education only and are not a substitute for professional assessment. If you are struggling, reach out to a qualified clinician; our guides to finding a therapist, psychiatrists vs. psychologists and free mental health resources can help you take the next step. If you or someone else is in immediate danger, see crisis resources.