Attention deficit hyperactivity disorder, or ADHD, is a psychological disorder characterized by impulsivity, hyperactivity, and short attention span. ADHD is often comorbid with other mood disorders, but if developmental disorders are present, ADHD is usually ruled out as symptoms are thought to be from the developmental disorder and not ADHD. Autism is characterized by resistance to change, speech and language problems, abnormal social interactions, and inconsistent intellectual performance.
Frequency
A study by Goldstein and Schwebach in 2004 found that 59 percent of those with autism or pervasive developmental disorder not otherwise specified (PDD-NOS) are comorbid for ADHD. It is unclear how many patients with ADHD are also comorbid for autism or autism spectrum disorder, as the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV), which is used by psychiatrists to diagnose both disorders, does not allow for ADHD patients to also be diagnosed as autistic.
Abnormal Social Interaction
A main symptom of autism is abnormal social interaction, including avoidance of eye gaze, lack of attachment to others, and inability to hug or cuddle. Patients with ADHD may not pay attention when others are speaking to them, talk excessively, blurt out answers to questions before they are finished, and interrupt others, thus creating abnormal social interactions. ADHD children may also have a hard time maintaining eye contact due to moving around excessively, squirming in their seats, or having poor attention. Some children with ADHD also feel overstimulated by certain tactile stimuli, such as clothing, or touching, leading to this being interpreted as an autistic symptom. One thing that distinguishes ADHD from autism is that ADHD children often want to make friends, but are disruptive and impulsive, driving friends away, while autistic children are either not interested in friends, or do not know how to initiate friendships.
Repetitive Behaviors
A second component of autism is repetitive behaviors, including obsession with familiar objects, resistance to change, and odd rituals and habits. Patients with ADHD usually require novelty due to poor attention spans and impulsivity. However, some patients become so super focused on things that interest them, for example, puzzles, or building things, and neglectful of other tasks, that they appear autistic.
Speech and Language Problems
A third component of autism is speech and language problems, including muteness, bizarre use of speech, or delayed onset of speech. Patients with ADHD do not often suffer from muteness, and instead are quite talkative. However, some ADHD patients do exhibit language oddities, such as making up their own languages. ADHD patients usually do not suffer from delayed speech onset, while most autistic patients do. Patients with ADHD do often have problems initiating conversations, or being able to have normal back and forth because they impulsively say what's on their minds before the forget, interrupting the other person, and not listening to what the other person is saying. This is often viewed as autistic.
Inconsistent Intellectual Performance
The last component of autism is inconsistent intellectual performance. Patients with ADHD often show inconsistent performance in school as they can be hyperfocused on a subject they really like and inattentive on subjects they dislike. Highly intelligent ADHD children can often be understimulated in school, and thus score high on standardized tests while failing regular classes.
References
- The Merck Manual: ADHD
- The Merck Manual: Autism
- "Attention-deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment," Russell A. Barkley; 2006.
- "Attention Deficits and Hyperactivity in Children and Adults: Diagnosis," Pasquale J. Accardo; 2000
- "Diagnosing Autism Spectrum Disorders: A Lifespan Perspective," Donald P. Gallo; 2010
