Comorbid Disorders

Most children with AD/HD will not have a completely “pure” AD/HD situation. In the majority of cases the children will have different, yet related, behavioral comorbid (coexisting) disorders. These may affect the outcome of managing AD/HD (such as in a specific math or reading/dyslexia disorder), or may confuse the diagnosis, constituting a different baseline disorder that behaves like AD/HD yet is not AD/HD (such as manic depressive disorder or a pervasive developmental disorder/autism).

The most common comorbid disorders include:

  1. Oppositional defiant disorder (or conduct disorder) occurring in about 50%
  2. Specific learning disorders occurring in about 20-30%
  3. Anxiety disorders occurring in about 20-30%
  4. Depressive disorder or tendencies occurring in about 30-40%
  5. Bipolar disorders (manic depressive) occurring in about 5%
  6. Tic disorders or Tourette’s disorder occurring in about 2-5%
  7. Pervasive developmental disorder/autism occurring in about 3-10%
  8. Social interaction impairments
  9. Obsessive-compulsive disorder
  10. Antisocial personality disorder (over 18 years of age)

One must also expect a different degree of the comorbid disorders. When it comes to the diagnosis of psychiatric conditions, the word “disorder” indicates that one meets clear clinical criteria for a certain diagnosis. However, an individual may have behavioral tendencies of one of the disorders without having the actual diagnosis. Usually the use of the word “disorder” implies that there is an associated, significant, functional impairment due to the difficulties related to the condition.

Oppositional defiant disorder (ODD)

The diagnosis of ODD requires a period of at least 6 months of negative, hostile, and defiant behavior. These kids frequently lose their temper, argue with adults, refuse to comply with rules, deliberately annoy people, blame others for their mistakes, get easily annoyed, are angry, defiant and vindictive. This becomes a “disorder” if there is a significant associated impairment; academic, social, occupational or behavioral.

Conduct disorder

A conduct disorder is a more severe form of ODD. There is a pervasive pattern of aggression towards people or animals. Physical fights, use of weapons, cruelty, destruction of property, theft, and violation of rules.

Anxiety disorders

These kids may try to hide their fears or rationalize them, but still may be afraid to stay home alone, go to the bath by themselves or to leave the house by themselves. They try to avoid certain situations such as social encounters and react with apparent irritability, unexplained crying or restless behaviors rather than admit or understand clearly that they have fears. This disorder is frequently associated with an obsessive-compulsive disorder and depression.

Obsessive-compulsive disorder (OCD)

Individuals with this disorder will have repetitive, unpleasant thoughts (obsessions) that are relieved by an unusual, ritualistic type behavior (compulsions.) Some compulsions consist of touching themselves symmetrically, washing hands frequently, holding their breath in certain situations, arranging objects, checking things frequently, and opening and closing doors repetitively. These actions may relieve the stress of the obsessions temporarily. The compulsive behaviors are known to the children to be strange, yet despite being bothered by the behaviors, they cannot help it. OCD and anxiety may be associated with the development of some nervous twitches and in extreme situations a tic disorder such as Tourette’s disorder.

Tic disorder

Tic disorders, such as Tourette’s, are disorders consisting of multiple daily motor tics of different kinds (eye blinking, facial grimacing, body jerking) and vocal tics (yelling, grunting, throat clearing) lasting for more than a year and causing a significant impairment. This disorder is important to recognize due to the fact that it may become worse as a result of treating the AD/HD symptoms with stimulant medication (Adderall and Ritalin.)

For more information, see our section devoted to tic disorders.


Depression is another condition frequently related to anxiety and OCD. Again, to qualify for major depression as a medical entity one must meet DSM V criteria. However, there may be milder degrees of depression associated with AD/HD. Moreover, frequently in children, depression will have an atypical presentation. In addition to the typical sense of worthlessness, guilt, or sadness, as well as decreased activity, some children may present with increased irritability and unusual behaviors. Depression may also develop due to the difficulties and impact on self esteem resulting from the frustration caused by AD/HD. Physicians and parents must also be sensitive to the possibility that depression results from a side effect of stimulant medication, usually caused by overdosing.

Autisim spectrum disorder (ASD)

ASD typically presents with a language delay. All children with AD/HD who have a history or a language delay must be considered for the possibility of ASD. The child will typically have poor eye contact, pervasive ignoring of other people, may develop normally and present with a regression of speech and interaction abilities at about 18 months of age.

For more information, see our section devoted to ASD/autism.

Other features of a ASD may include severe temper tantrums, especially when changing between activities, lack of interest in toys or other children, toe walking, hand flapping or bizarre play habits, such as arranging toys in rows, spinning objects or themselves, fascination with spinning objects, being in their own world or being unable to understand simple things or communicate them. Some of these children, when they become verbal, may repeat heard words, say the same phrase or repeat TV commercials over and over again and have a very unusually remarkable memory for certain details, such as train routes, numbers, dates or any field of their interest.) As they grow, many of the above mentioned symptoms may tone down. The eye contact improves, the pervasive ignoring disappears, but they remain with a poor understanding for social skills and their communication is impaired. Some of these children may also have persisting AD/HD symptoms that may respond well to treatment with stimulant medication, yet Anxiety, OCD, irritability and temper tantrums with anger outbursts may persist and worsen with the use of AD/HD medication at times.

Mental Retardation

Some (very few) children with AD/HD may have mental retardation. AD/HD may occur at any IQ level. Mental retardation is defined as an IQ score below 70 (as scored on the IQ testing.) A normal IQ score is 100. The normal range is between 80 to 120. An IQ of 70 to 80 is considered a borderline IQ. 50-70 is mild mental retardation (MR) and below 50 is a moderate MR. An IQ test may be of value in the evaluation of AD/HD in the sense that if the academic impairment does not correspond to the IQ ability, the difference between the actual performance and the IQ ability may be attributed to AD/HD. For example, in a child who has an IQ of 130, yet fails most of the academic subjects, one would expect him to be an A student based on the IQ. If this child meets criteria for AD/HD, the difference between their actual grade and their ability to be an A student may be attributed to the dysfunction caused by AD/HD. This child would be an excellent candidate for stimulant medication treatment and should be expected to do exceptionally well unless he has a separate specific learning disorder.

Specific learning disorders

These are disorders affecting specific learning skills despite a normal IQ ability. A reading disorder may be termed dyslexia, alexia or developmental word blindness. This occurs in about 4% of children. (See specific dyslexia section.)

Mathematical disorders occur in about 6% of the population and despite correction of AD/HD, these children will have a permanent degree of impairment understanding mathematical concepts.

These disorders are caused by a dysfunction of a specific region of the brain and may be evaluated with neuropsychiatric testing. The mathematical disorders are caused by a dysfunction of the right occipital lobe of the brain. Reading disorders may be localized in the temporal or parietal lobes.