What Are The Most Common 10 Types Of Mental Disorders?

Mental Disorders

Mental illnesses or mental disorders are defined as psychological abnormality.

Psychological abnormality in thinking, behavior and moods.

It is often associated with distress, impaired functioning or disability of some form.
There are a number of factors that can lead to mental illnesses. Genetics, biological and environmental factors can lead to mental disorders in men, women and children of all ages. To ensure that recovery and treatment measures are provided, it is extremely important to identify and diagnose these conditions.
Over the years with advances in clinical psychiatry, there have been a number of changes in the recognition of the types of mental disorders.

Classifying the Types of Mental Illnesses

The definitions and classifications of the various type of mental illnesses have undergone a number of changes. Currently there are two accepted systems of classifications of mental health disorders – one is done by ICD-10 Chapter V: Mental and behavioral disorders.

This manual has been published by the International Classification of Diseases, WHO since 1949.

The other is the Diagnostic and Statistical Manual of Mental Disorders (the fourth and latest edition is the DSM-IV) produced by the American Psychiatric Association (APA). This manual has been in publication since 1952 and is widely used in US while Britain and the rest of Europe follows the former code of classification provided by ICD.

Both these syndrome-based classifications, list a range of mental health conditions for example the DSM IV lists around 300 of mental disorders.

Along with this, the ICD-10 has included childhood disorders under two broad categories, Disorders of psychological children’s behavioral and emotional problems development (F80−89) and Behavioral and Emotional Disorder with onset usually occurring in childhood and adolescence (F90−98).

The DSM IV includes the childhood disorders under Axis I, Disruptive Behavior Disorder, Anxiety disorders of childhood or adolescence, eating disorders, tic disorders, elimination disorders and in Axis II under Pervasive developmental disorders.

The Most Common Mental Disorders In adults And Children

  1. Anxiety Disorders
  2. Childhood Disorders
  3. Cognitive Disorders
  4. Dissociative Disorders
  5. Eating Disorders
  6. Impulse Control Disorder
  7. Mood Disorders
  8. Organic Brain Disorders
  9. Personality Disorders
  10. Sexual Disorders
  11. Sleep Disorders
  12. Other Mental Disorders

Anxiety Disorders

Affecting around 40 million adults in America alone, anxiety disorders are extremely common and can affect anyone, be it adults or children. Unlike general bouts of anxiety once in a while, anxiety disorders are marked by extended periods of anxiety generally six months or more.


Generalized Anxiety Disorder

A person with generalized anxiety disorder has constant, excessive and irrational worry about anything be it family matters, money, relationships or work troubles. Fatigue, recurrent headaches, muscle aches, numbness of hands and feet, rashes, hot flashes and inability to control the anxiety are some of the common symptoms of this mental disorder

Panic Disorder

A type of anxiety disorder that affects both adults and children, panic disorders lead to several, recurrent panic attacks. Most of these attacks are sudden and are triggered off without any warning.

Common symptoms include intense anxiety, rapid heartbeat, dizziness, trembling and a feeling of intense, uncontrollable fear.

Specific Phobia

Derived from the Greek word Phobos, phobia is a feeling of intense fear of a specific thing that may or may not pose a danger to the person suffering from the fear. Proximity to the phobic stimulus can trigger off this irrational fear. Fear of spiders (arachnophobia), flying (aviophobia) and fear of dogs (Cynophobia) are some examples of specific phobias.

Social Anxiety Disorder

Also known as social phobia, social anxiety disorder is a type of anxiety disorder wherein a person feels extremely self-conscious and anxious in a social situation. He or she may start blushing, trembling, sweating profusely or have difficulty in conversing with people.

Obsessive Compulsive Disorder

Repeated and often unwanted feelings, ideas or obsessions can be caused by obsessive compulsive disorder. The repetitive obsession of some distressing thought or image and the compulsion to do a specific act, can leave the person anxious and tired all the time.

Some examples of obsessive compulsive behavior include repeated washing off hands to remove infection-carrying germs or checking and rechecking certain things like locking the door or switching off lights.

Post-Traumatic Stress Disorder

A traumatic experience like a natural disaster, hostage situations, abuse, bullying and rape can lead to post traumatic stress disorder. The person suffers from depression, anxiety and anger.

Repeated flashbacks of the traumatic event can further increase the distress.


Childhood Disorders

Like adult mental disorders, there are a number of childhood disorders as well. Child psychiatry studies have identified the need to study child psychology differently from adult psychology.

This is because a child is dependent on parents and caregivers for emotional and other development. Moreover, children are less expressive in their words, and thus the disorders are more difficult to diagnose.


Attention Deficit-Hyperactivity Disorder (ADHD/ADD)

One of the most common childhood disorders, attention deficit-hyperactivity disorder is characterized by hyperactive behavior, difficulty in paying attention and staying focused.

The child becomes easily distracted, misses out on things, switches from one activity to other, is constantly in motion, talks non-stop, and often does not listen when spoken to.

Autistic Disorder (Autism)

Autism or autistic disorder is a developmental disorder in which the child displays limited social communication and repetitive behavior. The symptoms can usually be seen at the preschool age.

Certain developmental deficits like no babbling at twelve months of age or no words spoken by eighteen months along with loss of language or social skills can indicate autism in babies.

In preschoolers, signs like lack of physical contact, avoiding eye contact and failure in communicating with others can indicate autism. The child may repeat certain behavior like stacking cups or placing things in a row.

He or she may have certain rituals, and be extremely preoccupied with lights and moving objects.

Conduct Disorder

When there is a repetitive and persistent violation of rules along with flouting the socially accepted behavior, it is known as conduct disorder in children. Some of the common behavior exhibited include aggression towards people, cruelty to animals, stealing, fighting, destruction of property and violations of rules at school and home


This is the voluntary soiling of the clothes due to withholding of the stool. The stool which collects in the colon can leak out and stain the clothes.

This is usually seen in toilet-trained toddlers above four years of age. Encopresis is a sign of constipation, or is caused by holding the stool due to psychological or neurological disorders.


Enuresis or bed wetting is the inability to control urination especially while sleeping. There are three types of enuresis including diurnal enuresis(daytime incontinence), nocturnal enuresis (nighttime incontinence) and mixed enuresis.

While primary enuresis refers to children who have not been toilet trained, secondary enuresis refers to toilet trained kids who have incontinence due to some stressful situation. The behavior must be observed twice for at least three weeks for it to be diagnosed as enuresis.

Learning Disorder

Learning disorders is an umbrella term to define a wide range of disorders related to learning difficulties. These disorders affect how the person listens, speaks, understands and puts learned things to use.

The learning disorders are grouped into different skill sets.

  • Learning disabilities in reading (dyslexia)
  • Learning disabilities in math (dyscalculia)
  • Learning disabilities in writing (dysgraphia)
  • Learning disabilities in language (aphasia/dysphasia)
  • Learning disabilities in motor skills (dyspraxia)
  • Visual processing Disorder
  • Audio Processing Disorder

Mental Retardation

Preferably known as intellectual disability, mental retardation is a developmental disability that is characterized by below average intellectual functioning and adaptive skills (skills needed for everyday life like learning language, social skills and work related skills).

It is often diagnosed in children less than eighteen years of age.

Oppositional Defiant Disorder

This is a disorder that is marked by hostility and defiance towards authority figures. Common symptoms of the disorder include extreme anger, refusal to comply with rules, saying hurtful things, mean and spiteful behavior in children.

The child may have frequent and inconsolable temper tantrums and anger outbursts.

Pica Disorder

When a child eats substances like clay, dirt, chalk or sand then he or she may have the pica disorder. This is especially true if the child continues to do so for more than a month.

Some of these substances can be toxic like the lead in paint or hairballs that can cause intestinal obstruction. Nutritional deficiencies like an iron deficiency, acquired taste or mental stressors like parental neglect, family issues and poverty can trigger off this disorder in children.

Reactive Attachment Disorder

A rare condition but one which can have serious implications, reactive attachment disorder is when a child fails to get attached to caregivers or parents due to abuse or neglect.

Orphaned children may suffer from this problem as well. The lack of necessary love and nurture can lead to withdrawing from others. The child is often not responsive to people, has no interest in playing with toys or other people and likes being alone.

In older children symptoms like aggressive behavior, obvious awkwardness and discomfort can be seen.

Rett’s Disorder

A neurodevelopmental disorder that affects girls only. Rett’s disorder is characterized by normal growth in the initial six months of the baby’s life, followed by a slowing in the development.

Slow head growth, problems with walking, wringing of hands, seizures and loss of muscle tone are some common physical symptoms. The developmental delay may be accompanied by a deterioration of the language and social skills.

Rumination Disorder

This is an eating disorder in children which is characterized by constant regurgitation and re-chewing of food that is undigested. This is more often seen in infants older than three months and rarely in younger children or adolescents.

This disorder is often accompanied by symptoms like bad breath, stomach indigestion, chapped lips and weight loss in babies.

Selective Mutism

This is a childhood psychological disorder in which a child who can speak restricts himself or herself from speaking in social settings or at school with unfamiliar people. This form of extreme social phobia is especially common in children who are younger than five years of age.

Separation Anxiety Disorder

Separation anxiety in children is described as a fear or anxiety over separation from the parent and home. The child may suffer from excessive distress and worry at the prospect of being separated from the primary caregiver and familiar surroundings.

They may refuse to go to school, be reluctant to sleep and have repeated nightmares about being separated. In some cases, the child may complain of imaginary illnesses like headaches and fever.

Stereotypic Movement Disorder

This is a mental disorder in children that is characterized by repetitive behavior like hand waving, biting oneself, nail biting or body rocking. The behavior often has a negative impact on the day-to-day life of the child and may even cause bodily harm

Tic Disorder

Abrupt, often painless, rapid movements or sounds are known as tics. There are two types of tics, motor and vocal tics.

Motor tics can range from being simple tics like eye blinking or head jerks or complex tics like biting, banging and making obscene gestures.

Similarly vocal tics can range from meaningless sounds to complex vocal tics like coprolalia wherein obscene gestures and sounds are made.

When both motor and vocal tics are present it is known as Tourette’s disorder which is a more complex form of tic disorder.


Cognitive Disorders

Cognitive disorders affect the learning, memory, problem solving and perception. Contrary to popular assumption, cognitive disorders are not just suffered by the elderly.

People of all ages can have cognitive disorders like delirium and dementia. It can be a result of substance abuse, some medical condition or a combination of both.


Delirium is a mental disorder that is characterized by a difficulty in understanding the situation and a disturbance of the individual’s consciousness. The person may exhibit symptoms such as purposelessness, random behavior and actions.

There may be a change in the sleep and wake cycle. Moreover, the thought process is disorganized and the speech, memory and concentration of the person may be impaired.



Dementia is described as a disorder that is characterized by a loss of a person’s memory due to certain factors including brain trauma or stroke. Diseases like Parkinson’s disease and Alzheimer’s disease can also lead to this mental disorder.

In such a case it is known as Dementia of Alzheimer’s type or Dementia due to HIV.


Dissociative Disorders

When there is a disruption or a complete breakdown of a person’s memory, perception and awareness then it is known as dissociative disorder. The thoughts, feelings and sensations of a person become disconnected from one another.

Often caused by psychological trauma especially during childhood and adolescence, dissociative disorder can range from amnesia to a multiple personality disorder.


Depersonalization Disorder

Is there a feeling of being cut off from oneself and watching own actions from afar? Then it can be a sign of depersonalization disorder.

These periods of detachment can be recurrent and persistent, thus resulting in dysfunction and distress in an individual. Sometimes emotional stress, sleep deprivations and use of alcohol can trigger off a random episode of this detachment in healthy individuals.

However, if there are persistent and recurrent episodes of the same then it can be a sign of the disorder.

Dissociative Amnesia

A loss of memory about a significant period of time or inability to recall vital personal information is known as dissociative amnesia. This can be caused by an episode of a single extremely stressful situation like an accident.

Dissociative Fugue

Caused by a single stressful event, dissociative fugue is a type of dissociative disorder wherein a person constructs a whole new identity to replace the confusion regarding the actual identity. Unable to recall the past, the person connects totally with the new identity while totally relinquishing the memories of the former identity.

Dissociative identity disorder (Multiple Personality Disorder)

Also known as Multiple Personality disorder, the dissociative identity disorder is characterized by two or more different identities or personalities of a person and inability to recollect the memories of each personality state. The different personalities may take control over the thoughts and actions at different times.

Severe depersonalization and detachment from the surroundings can be witnessed.

Dissociative disorder Not Otherwise Specified (NOS)

Other than these types of dissociative behavior, a person may suffer from mood swings, phobias, substance abuse, suicidal tendencies and various health problems which are in some way associated with dissociative disorder.


Eating Disorders

Defined as either excessive or extremely restrictive food intake, eating disorders can severely harm a person’s health. The preoccupation with food and health is so much that a person has little time to think of anything else.

Anorexia Nervosa

Characterized by an irrational fear of putting on weight and a severely restricted diet, anorexia nervosa is a common eating disorder among many young men and women. These food restrictions lead to severe weight loss and other metabolic and hormonal changes.

The person often has a negative self image, exercises too much and is always preoccupied with food. Constipation, menstrual irregularities, pain in abdomen, low blood pressure and dehydration are some of the common signs of this disorder.

Extreme cases of anorexia can lead to multi-organ failure and brain damage.

Bulimia Nervosa

Frequent episodes of eating large amounts of food followed by feeling of guilt and compensatory behavior like forced vomiting and excessive exercising is known as bulimia nervosa. Common symptoms of this disorder include swollen glands, inflamed throat, acid reflux, severe dehydration and an electrolyte imbalance.

Binge Eating

Binge eating disorder is when a person loses control over their eating. Obesity along with related diseases like cardiovascular problems are some of the common effects of binge eating.

After consuming the excess food, feelings of guilt and depression follow. This can be accompanied by even more eating.


Impulse Control Disorder

Impulse control disorder is a type of psychological disorder wherein a person is unable to resist the urge or the temptation to engage in an action that might harm him or her or even others.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) manual there are a number of types of impulse control behavior, prominent among which are:

  • Intermittent Explosive Disorder: Intermittent Explosive Disorder or IED include extreme manifestations of anger in an individual due to real or perceived provocations. This can lead to aggressive acts like destroying property or assaulting someone.
  • Kleptomania: The impulsive urge to steal something without considering the item’s monetary value or use. The stealing is done for gratification and fulfillment of committing the theft.
  • Pathological Gambling: The urge to continuously gamble despite knowing about the harmful effects of the same is known as pathological gambling or problem gambling. This uncontrollable impulse to gamble can have significant negative effects on someone’s life including financial problems, disrupted family life and other such effects.
  • Pyromania: Pyromania is an impulse control disorder wherein a person feels the uncontrollable urge to set fire. This is often done without any motive and just for the gratification of setting fire.
  • Trichotillomania: Identified as an overwhelming urge to pluck one’s hair. Trichotillomania can lead to noticeable hair loss especially around the eyebrows, head, eyelashes and hands.

Other types of impulse control disorders that are not specified include:

  • internet addiction,
  • dermatillomania (skin picking)
  • onchycophagia (nail biting)
  • compulsive shopping.

Mood Disorders

Mood disorders are some of the most common types of mental disorders affecting people around the world. These disorders signify a major change in a person’s mood.

Among them, depression and bipolar disorder are two emotionally crippling mental illnesses that can severely affect a person’s life. Whereas dysthymic disorder and cyclothymic disorder are some moderate forms of mood disorders.

Major Depression

Also known as clinical depression or unipolar depression, major depression is a mood disorder wherein a person suffers from extremely low self-esteem and lack of interest.

It can affect a person’s day-to-day life. The feelings of hopelessness, lack of self worth, inappropriate amount of guilt and obsessive thoughts are some of the symptoms of this disorder.

In severe cases the person may suffer from insomnia, memory loss, delusions and thoughts of suicide.

Bipolar Disorder

Bipolar disorder is often referred to as manic depression or manic depressive illness. A person with bipolar disorder can suffer from frequent mood swings.

A frenzied state of mania wherein a person appears energetic and excited is often followed by a state of depression. When the person has a manic episode he or she may feel extremely happy or be in an irritable and jumpy mood.

They may talk fast, be easily distracted and jump from one idea to another. This is contrasted with depressive episode when there is a long periods of “feeling low” along with fatigue, inability to concentrate and change in habits.

The person may have constant thoughts of suicide.

Dysthymic Disorder

Dysthymia is a persistent mood depression which is not severe enough to be classified under major depression. In this condition a person is hounded with a depressive feeling for more than two years and often has symptoms like poor appetite, low self-esteem, trouble concentrating and insomnia.

Cyclothymic Disorder

A milder form of the severe bipolar disorder, cyclothymic disorder also results in mild forms of mania and depression phases. Some of the common symptoms of cyclothymic disorder is alternate periods of euphoria and depression over a period of two years with less than two symptom free months.

The periods of depression usually tends to extend more than the mania phase.

Seasonal Affective Disorder (SAD)

Referred to as winter blues or summer blues , seasonal affective disorder is a type of mood disorder wherein people experience changes in the mood with weather changes.


Organic Brain Disorders

These types of disorders are the direct result of physical changes that affect the brain. In other words, there are various diseases and disorders that can affect or damage the brain, leading to an impaired mental function.

The term is used to denote physical disorders than can lead to mental illnesses and not the psychiatric ones. However, the demarcation between the two is almost impossible in many cases.

So, this term is not widely used nowadays.

The following are some of the mental illnesses that come under the term organic brain disorder/organic brain disease/organic brain syndrome.

  • Huntington disease: An inherited disease that affects the brain, Huntington disease causes progressive breakdown of the nerve cells in the brain, leading to functional, cognitive and psychiatric problems.
  • Multiple sclerosis: A degenerative disease, multiple sclerosis affects the myelin sheath covering of the nerve cells, thereby slowing down or stopping the nerve impulses. This disorder affects the central nervous system (brain & spinal cord), causing a wide range of physical as well as mental symptoms.
  • Alzheimer’s disease: One of the common causes of dementia (loss of brain function caused by certain diseases), Alzheimer’s disease is characterized by degeneration and death of brain cells, thereby affecting the mental function.
  • Parkinson’s Disease: This is a degenerative disorder of the central nervous system. The condition affects the nerve cells’ ability to send messages and cause tremors that may even lead to paralysis.

There are various cardiovascular diseases that may affect the functioning of the brain and lead to certain mental illnesses. These include stroke, cardiac arrhythmias, infections of the heart, etc.

Sometimes mental disorders can be trauma-induced. For example, a head injury can affect the brain and cause damage to the organ, causing mental disorders.

Other medical conditions that can affect brain functioning include cancer, thyroid problems, liver and kidney diseases, infections (like septicemia), certain vitamin deficiencies (like B12), drug and alcohol related – intoxication, drug and alcohol withdrawal symptoms, etc.

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