Mental Illness
Mental illness refers to a wide range of medical conditions that are most evident in a person’s feelings, thought patterns, and behaviors rather than in physical injury or ailment.

Symptoms of mental illness can include feelings of intense sadness, confusion and poor concentration, excessive worry or guilt, mood swings, pronounced antisocial tendencies, lethargy or lack of energy, difficulty dealing with stress, and changes in eating habits or sex drive. In more severe cases, symptoms may include alcohol or drug abuse, paranoia, hallucinations, explosive temper or fits of violence, feelings of alienation, and suicidal thoughts. 

Acute Stress Disorder
Acute stress disorder is diagnosed when a person develops severe symptoms after exposure to actual or threatened death, serious injury or sexual violation through direct experience, as a witness, through learning that the event happened to a close family member or friend, or through repeated or extreme exposure to terrible details of the traumatic event (common in first responders). 

Adjustment Disorders
Feeling worried, overwhelmed or sad in response to a stressful event is very normal. In the case of a major life change, loss of a loved one or other emotionally taxing event, you may feel anxious, have difficulty concentrating, cry more than usual, experience sleep and appetite disruption, or avoid social situations. But if you experience more stress than would be expected in response to the stressful event, you may have an adjustment disorder.

Agoraphobia
Agoraphobia is an excessive, overwhelming fear of certain places and situations. Many people with this condition feel powerless, cornered, trapped, or humiliated in public spaces. Even the anticipation of stressful situations—such as riding in an evaluator or being in a crowd—might trigger a panic attack. In severe cases of agoraphobia, individuals might sequester inside their homes. For some, they may feel unable to go outside.

Anorexia Nervosa
Anorexia nervosa, anorexia for short, is an eating disorder marked by obsessive weight loss and food refusal. Persons with anorexia see achieving thinness as an overriding goal in their lives, even if the resultant low body weight is unhealthy and a threat to wellbeing. Weight loss is typically attained through self-starvation or food purgation, as well as over exercise and the inappropriate use of laxatives and dietary aids. The negative effects of anorexia can include hair loss, organ damage, osteoporosis or bone-thinning, heart and cardiopulmonary issues, electrolyte imbalances, and death.

Antisocial Personality Disorder
Antisocial personality disorder, or ASPD, is a mental-health condition in which individuals place little value on the rights, feelings, or welfare of others. Persons with ASPD are often cold, manipulative, reckless, and unconcerned with anyone’s well-being but their own, though they may cultivate a superficial charm to enlist aid when they need it. These individuals lack a moral compass, have little regard for human relationships, and are indifferent to the anxiety or pain that they cause. 

Attention Deficit Hyperactivity Disorder
Everyone gets distracted sometimes. Lack of sleep, stress and trying to do too much at once can all lead to problems focusing on a particular task. It’s also normal for people – especially children – to be restless, fidgety or irritable from time to time. But in attention deficit hyperactivity disorder, commonly known as ADHD, symptoms of inattention, hyperactivity and impulsivity are present most of the time and disrupt a person’s social, work and/or school life.

Autism Spectrum Disorder
Autism spectrum disorder or ASD is a developmental condition that results in serious, and sometimes severe, communication and sociability problems. Persons with ASD experience considerable difficulty with ordinary social interactions that most individuals take for granted. That said, there is a great range of symptoms associated with autism, which manifest differently for every person with the condition. Though all face challenges in daily living, some are also gifted with unusual abilities in cognition and memory. Symptoms typically appear by age two or three.

Binge-Eating Disorder
Binge-Eating Disorder, or BED, is an eating disorder in which an individual frequently consumes excessive amounts of food and feels unable to stop. Binge eating is characterized as eating in a short amount of time (within any two-hour period), an amount of food that is unusually larger than what most people would consume in a similar time period, under similar circumstances. A hallmark trait of binge eating is the feeling of being out of control and having an inability to stop eating. 

Bipolar I Disorder
Unusual shifts in mood, energy and activity levels could indicate bipolar I disorder, the more severe form of bipolar disorder. Bipolar I disorder, also known as manic-depressive disorder, is diagnosed when a person has experienced at least one manic episode. A manic episode is a distinct period of abnormally and persistently elevated, expansive or irritable mood accompanied by abnormally and persistently increased activity or energy. These episodes last at least one week and are present most of the day, nearly every day.

Bipolar II Disorder
Bipolar disorder is a condition that causes unusual shifts in mood, energy, activity levels and the ability to carry out day-to-day tasks. Bipolar II disorder is diagnosed when a person experiences a pattern of depressive episodes and hypomanic episodes, but not the full-blown manic episodes found in bipolar I disorder. However, some Bipolar II patients may have longer lasting and more severe bouts of depression.

Borderline Personality Disorder
Borderline personality disorder, or BPD, is a behavioral-health condition characterized by emotional turbulence, violent mood swings, gnawing self-doubt, and difficulty in maintaining long-lasting relationships. The lashing-out at others is often rooted in fears of abandonment and isolation. Borderline personality disorder typically manifests in early adulthood and is more common in women than men. 

Bulimia
Bulimia nervosa – bulimia for short – is a potentially dangerous eating disorder marked by cycles of overeating followed by compensatory behaviors, including forced vomiting – binging and purging. Other forms of purging include the use of laxatives and diuretics and harsh exercise regimens. Often, the binge-and-purge cycle is pursued in secret. The potential for physical harm with bulimia is considerable, and includes tooth decay, fertility issues, gastrointestinal maladies, arrhythmias, heart disease, and death.

Conduct Disorder
Conduct disorder is an antisocial behavioral disorder in children and adolescents. Those with this condition tend toward disruptive and violent behavior, including rule breaking, backtalk, lying, petty theft, bullying, and fighting. Conduct disorder is often a precursor to antisocial personality disorder.

Conversion Disorder
A conversion disorder, also called functional neurologic disorder, is a medical condition in which the patient loses the use of some part of his or her body without an apparent physiological reason. These losses typically affect either physical mobility or the senses (sight, hearing, etc.). Conversion disorder is often, though not always, triggered by stressful events or life situations. 

Cyclothymia (Cyclothymic Disorder)
Cyclothymia (cyclothymic disorder) is a mild mood disorder that causes emotional ups and downs. When doctors give a cyclothymia definition, they usually mention mood fluctuations, depression, and hypomania. Patients with cyclothymia experience short periods of depression and mania that rarely reach full expression. 

Dependent Personality Disorder (DPD)
Dependent personality disorder (DPD) is an excessive dependence on others to meet your emotional and physical needs. DPD is marked by anxiety and often develops in childhood. Almost everyone with DPD develops the conditions before the age of 29.

Diogenes Syndrome
Diogenes syndrome is a behavioral-health condition characterized by poor personal hygiene, hoarding, and unkempt living conditions. It is most common in older men and women, which is why it is also called senile squalor syndrome. Persons with Diogenes syndrome demonstrate little concern for self-care or a clean living environment and seem frankly undisturbed about their condition or how others respond to it. 

Dissociative-Identity Disorder (DID)
Dissociative-identity disorder, also known as DID or DID disorder, is a complex psychological condition in which a person develops one or more alternate personalities typically as a coping mechanism for extreme trauma or abuse that occurred in early childhood. DID is sometimes referred to as multiple-personality disorder. A person with dissociative-identity disorder has the ability to switch personalities, often without warning, leading to changes in behavior, appearance, mannerisms, and even self-identity.

Generalized Anxiety Disorder (GAD)
Occasional anxiety can be a normal part of life. But people with generalized anxiety disorder experience persistent and extreme worry out of proportion to the actual likelihood or impact of an anticipated event. This chronic anxiety results in physical symptoms which interfere with managing tasks of everyday living to the point of being debilitating.

Major Depressive Disorder (MDD)
While everyone experiences sadness or depression from time to time, major depressive disorder – also known as clinical depression – is defined as a depressed mood or loss of interest or pleasure in almost all activities that persists for at least two weeks and represents a change from previous functioning. Major depressive disorder can be diagnosed as mild, moderate or severe, and psychotic symptoms – such as delusions or hallucinations – may be present.

Mild and Major Neurocognitive Disorders
Major and mild neurocognitive disorders were previously known as dementia. If a person is experiencing noticeable memory loss, difficulty communicating, significant problems handling daily tasks, confusion, personality changes, and mood or behavioral symptoms – he or she may have a neurocognitive disorder.

Oppositional Defiant Disorder
It’s not unusual for children to experience occasional bad moods and periods of increased irritability, defiance and argumentativeness. But if your child shows a pattern of angry or irritable mood, argumentative and/or defiant behavior, or vindictiveness toward people in authority lasting at least six months, he or she may have oppositional defiant disorder (ODD). 

Panic Disorder
Feelings of intense fear – and physical manifestations of that fear – are very common if someone is facing immediate danger or a perceived threat. In panic disorder, however, a person experiences recurrent unexpected panic attacks (abrupt surges of intense fear or discomfort accompanied by physical and cognitive symptoms) even when they are not in any danger. Panic attacks – which typically reach a peak within minutes – may occur in response to a known feared object or situation, or they may seem to appear out of the blue.

Persistent Depressive Disorder
While not as serious or disabling as other forms of clinical depression, persistent depressive disorder (PDD), also known as dysthymia, is a more chronic form of persistent depression. It is characterized by a depressed mood or loss of interest or pleasure in almost all activities most of the time for at least two years. 

Post-Traumatic Stress Disorder
For many people who witness or experience a shocking, scary or dangerous event, flashbacks, nightmares, anxiety or mentally reliving the event are temporary symptoms. When those symptoms don’t go away and become debilitating, a person may be diagnosed with post-traumatic stress syndrome (PTSD).

Psychosis
Psychosis is a symptom of a mental health disorder, or an underlying medical or neurological issue. Psychosis is often used as criteria to rule out and determine a specific mental health disorder. The fundamental component of psychosis is a loss of connection with reality that is often demonstrated through perceptual distortions, such as visual or auditory hallucinations (seeing or hearing things that aren’t there), and delusions (a belief or perception that isn’t grounded in reality). Onset of psychosis can begin in late teen years through mid-twenties People who are affected by psychosis may also exhibit behaviors that can be harmful to themselves and others. 

Reactive Attachment Disorder in Children
Babies develop attachments to parents or caregivers when those adults comfort them and otherwise attend to their needs. If a baby or young child experiences a severe disruption in these early relationships, especially if he or she has been neglected or physically or emotionally abused, the child may develop serious problems with emotional attachments to others. This rare condition is known as reactive attachment disorder (RAD). 

Schizoaffective Disorder
Schizoaffective Disorder is a chronic mental health disorder that exhibits symptoms of both schizophrenia (hallucinations or delusions) and a mood disorder (depression or mania). The disorder can resemble bipolar disorder or major depressive disorder, and can sometimes get misdiagnosed. The disorder, if left untreated, can cause significant issues in daily functioning, such as issues at work, school, or in relationships. People often withdraw socially and suffer from loneliness. 

Schizophrenia
Schizophrenia is a severe and chronic mental disorder that affects approximately one percent of the population. Symptoms include losing touch with reality, disruption to normal emotions and behaviors as well as memory problems. Schizophrenia is a treatable mental disorder, but it requires lifelong management. Schizophrenia is caused by a combination of things, including genetics, environment and brain chemistry. While there is no cure for this disorder, it can be managed through medication, psychotherapy and other care services.

Seasonal Affective Disorder (SAD)
Seasonal affective disorder, or SAD, is a type of depression that is linked to the changing seasons. It occurs most commonly in the late fall and winter months, but also occasionally during spring and early summer. About five percent of American adults experience SAD. Hormonal imbalances likely play a role in the onset of this condition. Several treatment options are available, including therapy and medication.

Separation Anxiety Disorder
Separation anxiety disorder (SAD) is a developmentally inappropriate and excessive fear or anxiety concerning separation from those to whom the individual is attached. Simply put, it is an intense fear of separation from loved ones, including people and pets. Separation anxiety is a normal part of childhood development and commonly occurs in infants and toddlers. Three to four percent of children are diagnosed with the disorder. SAD symptoms typically disappear around age 3. 

Social Anxiety (Social Phobia)
Social anxiety, sometimes called social phobia, is an exaggerated fear of being in social situations, with concerns over negative judgement and criticism based on your ability to communicate or perform. The most severe version, called social anxiety disorder, can lead to crippling levels of personal invisibility, with problems arising at school, work, and in relationships, as you avoid necessary contact with others. Social anxiety typically first becomes evident in the early teenage years.

Somatic Symptom Disorder
Somatic symptom disorder is when a person focuses excessively on physical symptoms. They typically believe that they have a medical condition regardless of an official diagnosis or medical assurance of their health and wellbeing. The obsessive focus on their symptoms often interferes with their day-to-day life.

Substance Use Disorder
Many adults can enjoy an occasional alcoholic drink safely and without ill effects on their health, ability to function at work or home, or mental state. Tobacco use is also common, and most people who use these substances do not have a mental health disorder. Substance use disorders – which can be mild, moderate or severe – occur when a person’s recurrent use of alcohol, tobacco and/or drugs causes health problems, disability, or failure to meet major responsibilities at work, school or home. Someone with a substance use disorder exhibits impaired control, problems with social interactions and risky behaviors.

Trichotillomania (Hair-Pulling Disorder)
Trichotillomania (Hair-Pulling Disorder) is the uncontrollable urge to pull out your hair. Individuals with trichotillomania often pull hair from their scalp, eyelashes, and eyebrows. Trichotillomania is an impulse control disorder. While those with the condition recognize the urge to pull hair, they find it difficult or impossible to control the urge.