Attention Deficit Hyperactivity Disorder - Attention Deficit Hyperactivity Disorder Causes

Written by NIMH

This study also showed that the ADHD children who were on medication had a white matter volume that did not differ from that of controls. Those never-medicated patients had an abnormally small volume of white matter. The white matter consists of fibers that establish long-distance connections between brain regions. It normally thickens as a child grows older and the brain matures.⁹

Although this long-term study used MRI to scan the children's brains, the researchers stressed that MRI remains a research tool and cannot be used to diagnose ADHD in any given child. This is true for other neurological methods of evaluating the brain, such as PET and SPECT.

Disorders that Sometimes Accompany ADHD

Learning Disabilities.

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Many children with ADHD—approximately 20 to 30 percent—also have a specific learning disability (LD).¹⁰ In preschool years, these disabilities include difficulty in understanding certain sounds or words and/or difficulty in expressing oneself in words. In school age children, reading or spelling disabilities, writing disorders, and arithmetic disorders may appear. A type of reading disorder, dyslexia, is quite widespread. Reading disabilities affect up to 8 percent of elementary school children.

Tourette Syndrome.

A very small proportion of people with ADHD have a neurological disorder called Tourette syndrome. People with Tourette syndrome have various nervous tics and repetitive mannerisms, such as eye blinks, facial twitches, or grimacing. Others may clear their throats frequently, snort, sniff, or bark out words. These behaviors can be controlled with medication. While very few children have this syndrome, many of the cases of Tourette syndrome have associated ADHD. In such cases, both disorders often require treatment that may include medications.

Oppositional Defiant Disorder.

As many as one-third to one-half of all children with ADHD—mostly boys—have another condition, known as oppositional defiant disorder (ODD). These children are often defiant, stubborn, non-compliant, have outbursts of temper, or become belligerent. They argue with adults and refuse to obey.

Conduct Disorder.

About 20 to 40 percent of ADHD children may eventually develop conduct disorder (CD), a more serious pattern of antisocial behavior. These children frequently lie or steal, fight with or bully others, and are at a real risk of getting into trouble at school or with the police. They violate the basic rights of other people, are aggressive toward people and/or animals, destroy property, break into people's homes, commit thefts, carry or use weapons, or engage in vandalism. These children or teens are at greater risk for substance use experimentation, and later dependence and abuse. They need immediate help.

Anxiety and Depression.

Some children with ADHD often have co-occurring anxiety or depression. If the anxiety or depression is recognized and treated, the child will be better able to handle the problems that accompany ADHD. Conversely, effective treatment of ADHD can have a positive impact on anxiety as the child is better able to master academic tasks.

Bipolar Disorder.

There are no accurate statistics on how many children with ADHD also have bipolar disorder. Differentiating between ADHD and bipolar disorder in childhood can be difficult. In its classic form, bipolar disorder is characterized by mood cycling between periods of intense highs and lows. But in children, bipolar disorder often seems to be a rather chronic mood dysregulation with a mixture of elation, depression, and irritability. Furthermore, there are some symptoms that can be present both in ADHD and bipolar disorder, such as a high level of energy and a reduced need for sleep. Of the symptoms differentiating children with ADHD from those with bipolar disorder, elated mood and grandiosity of the bipolar child are distinguishing characteristics.¹¹

The Treatment of ADHD

Every family wants to determine what treatment will be most effective for their child. This question needs to be answered by each family in consultation with their health care professional. To help families make this important decision, the National Institute of Mental Health (NIMH) has funded many studies of treatments for ADHD and has conducted the most intensive study ever undertaken for evaluating the treatment of this disorder. This study is known as the Multimodal Treatment Study of Children with Attention Deficit Hyperactivity Disorder (MTA).¹² The NIMH is now conducting a clinical trial for younger children ages 3 to 5.5 years (Treatment of ADHD in Preschool-Age Children).