Evidence-Based Supplement & Herb Guides

Oppositional Defiant Disorder in Children: Symptoms, Evaluation, and Warning Signs

Learn what oppositional defiant disorder is, how ODD symptoms differ from typical defiance, what causes may contribute, and when professional evaluation matters.

Oppositional defiant disorder is more than occasional arguing, stubbornness, or limit-testing. It describes a persistent pattern of angry or irritable mood, argumentative or defiant...

Onychophagia in Adults and Children: Symptoms and Risks

Learn what onychophagia means, how chronic nail biting appears, what may contribute to it, what it can be confused with, and when symptoms or complications may need professional evaluation.

Onychophagia is the medical term for chronic nail biting. Many people bite their nails occasionally, especially during stress, boredom, or concentration. It becomes more...

Olfactory Reference Syndrome Signs, Risk Factors, and Effects

A clear guide to olfactory reference syndrome, including its main symptoms, signs, thought patterns, possible causes, risk factors, diagnostic context, and complications.

Olfactory reference syndrome is a mental health condition in which a person becomes persistently preoccupied with the belief that they are giving off an...

Olfactory Hallucinations and Phantosmia: Symptoms and Possible Causes

Understand olfactory hallucinations, including phantom smell symptoms, common causes, mental health and neurological context, risk factors, complications, and warning signs that may need professional evaluation.

A smell that no one else can detect can be unsettling, especially when it is strong, unpleasant, or keeps returning. Olfactory hallucinations are real...

Obsessive-Compulsive Personality Disorder Symptoms, Signs, Causes, and Complications

Learn what obsessive-compulsive personality disorder is, how OCPD differs from OCD and perfectionism, and which signs, causes, risks, and complications matter most.

Obsessive-compulsive personality disorder, often shortened to OCPD, is a long-standing pattern of perfectionism, orderliness, control, rigidity, and overconscientiousness that can interfere with work, relationships,...

Obsessive-Compulsive Disorder (OCD): Signs, Risk Factors, and Diagnostic Context

A clear guide to OCD symptoms, signs, causes, risk factors, diagnostic context, common look-alike conditions, and complications that may require professional evaluation.

Obsessive-compulsive disorder is often misunderstood as a preference for neatness, caution, or order. In clinical use, OCD refers to a pattern of unwanted intrusive...

Obsessive Rumination Disorder Signs and Related Mental Health Conditions

Obsessive rumination involves repetitive, intrusive thought loops that can resemble OCD, anxiety, depression, or trauma-related symptoms. Learn the signs, causes, risk factors, complications, and when professional evaluation may matter.

Obsessive rumination is a pattern of repetitive, hard-to-stop thinking that feels intrusive, distressing, and mentally consuming. People may replay conversations, analyze mistakes, question their...

Obsessive Love Disorder and Romantic Fixation: Symptoms and Risks

Obsessive romantic fixation can involve intrusive thoughts, jealousy, possessiveness, and boundary problems. Learn what obsessive love disorder means, what it may be confused with, and when symptoms may require professional evaluation.

Intense romantic attachment can be emotionally powerful without being unhealthy. The concern begins when attachment becomes rigid, intrusive, possessive, or disconnected from reality, especially...

Obsessive Jealousy Overview: Symptoms, Signs, Causes, and Risks

Learn how obsessive jealousy differs from normal insecurity, what symptoms and warning signs to watch for, what conditions may be involved, and when urgent evaluation may matter.

Obsessive jealousy is more than ordinary insecurity in a relationship. It involves repeated, distressing, or hard-to-control preoccupation with a partner’s possible unfaithfulness, loss of...

Nymphomania (Hypersexuality): Signs, Risk Factors, and Diagnostic Context

A clear, stigma-aware guide to nymphomania, hypersexuality, and compulsive sexual behavior, including symptoms, diagnostic context, causes, risk factors, complications, and when evaluation may matter.

“Nymphomania” is an older term that was historically used to describe what people now more often call hypersexuality, compulsive sexual behavior, or compulsive sexual...

Nonverbal Learning Disorder Overview: Visual-Spatial Symptoms and Diagnostic Context

Clear overview of nonverbal learning disorder, including visual-spatial symptoms, signs by age, possible causes, risk factors, diagnostic context, common overlaps, and complications.

Nonverbal learning disorder is a neurodevelopmental profile marked mainly by difficulty processing visual and spatial information. The name can be confusing: it does not...

Non-Organic Psychosis Signs and Symptoms: How It Can Present

A clear guide to non-organic psychosis, including what the term means, common symptoms and signs, possible causes, risk factors, related conditions, diagnostic context, and complications.

Psychosis is a state in which a person has difficulty distinguishing what is real from what is not. It can involve hallucinations, delusions, disorganized...

Noise Sensitivity Disorder in Adults and Children: Signs and Diagnostic Context

Clear overview of noise sensitivity disorder, including symptoms, signs, causes, risk factors, complications, and how clinicians distinguish hyperacusis, misophonia, phonophobia, and sensory overload.

Everyday sound can feel harmless to one person and unbearable to another. For some people, certain noises feel painfully loud, emotionally triggering, threatening, distracting,...

Nocturnal Panic Attacks: Symptoms, Signs, Causes, and Risk Factors

Nocturnal panic attacks can cause sudden awakening with racing heart, air hunger, chest tightness, shaking, and intense fear. Learn how they differ from nightmares, sleep terrors, sleep apnea, seizures, and other conditions, plus when evaluation may matter.

Waking suddenly in intense fear can be disorienting, especially when it happens from sleep with no obvious warning. A nocturnal panic attack can feel...

Nihilistic Delusion Signs, Common Beliefs, and Related Conditions

Understand what nihilistic delusion means, how it differs from hopelessness or depersonalization, which symptoms may appear, and when urgent evaluation may be needed.

A nihilistic delusion is a fixed false belief that something essential has ceased to exist. It may involve the person’s body, identity, organs, mind,...

Nightmare Disorder Overview: Symptoms, Causes, and When Evaluation Matters

Learn what nightmare disorder is, how it differs from common nightmares and night terrors, what symptoms and risk factors matter, and when professional evaluation may be needed.

Nightmares are common, especially during stress, illness, poor sleep, or major life changes. Nightmare disorder is different. It involves repeated, disturbing dreams that are...

Night Terror Disorder: Symptoms, Signs, Causes, and Risk Factors

Learn what night terror disorder is, how sleep terrors differ from nightmares and seizures, what signs to watch for, and when nighttime episodes may need professional evaluation.

Night terror disorder involves repeated episodes of intense fear during sleep in which a person may scream, sit up, thrash, appear panicked, or seem...

Night Eating Syndrome Overview: Signs, Causes, and Diagnostic Context

A clear guide to night eating syndrome, including its symptoms, warning signs, possible causes, risk factors, complications, and how clinicians distinguish it from similar eating and sleep disorders.

Night eating syndrome is a pattern of eating and sleep disruption in which a person repeatedly eats a large share of their daily food...

Neurotic Depression Causes, Symptoms, and Conditions That Look Similar

Learn what neurotic depression means today, how it relates to chronic depression and dysthymia, and the symptoms, causes, risks, diagnostic context, and complications to watch for.

“Neurotic depression” is an older term that is still sometimes used in conversation, older medical records, and some international or historical psychiatric writing. In...

Neurosis Symptoms and Signs: What the Term Means in Mental Health

A clear guide to what neurosis means today, how it differs from modern mental health diagnoses, which symptoms and risk factors may be involved, and when evaluation may be important.

Neurosis is an older mental health term that many people still use to describe ongoing anxiety, worry, emotional distress, compulsive habits, or stress-related physical...