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The Fine Line Between Adult Autism Spectrum Disorder And Attention Deficit Disorder

Autism Spectrum Disorder in adults and Attention Deficit Disorder may be one and the same.

Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder (ADHD) are considered separate, distinct conditions, having different origins and different sets of symptoms, each requiring different diagnostic guidelines. In actuality, this assumption of a clear, significant distinction between these disorders is debatable. In my opinion, whatever distinctions that might exist are minimal. In fact, a more accurate view is that they are the same disorder, differing only in the fact that they appear diverse at different phases of a person’s life. Let me explain.

Both ASD and ADHD affect people in three areas: communication, social competency, and behavior. Each of these areas is, in turn, the result of similar core deficits.

Executive Functioning

Executive functioning allows a person to shift attention flexibly, inhibit irrelevant responses, create goal-directed behavior and solve problems in a planned, strategic way. Executive functioning allows a person to act deliberately by shifting attention to important tasks, regulating responses, setting goals, and using reasoning, judgement, and planning to solve problems.

It is this function of the brain that controls attentiveness, inhibits behavior, and allows a person to act purposefully in a social environment. When there is a deficit in executive functioning, one is typically inattentive, distractible and impulsive. This might result in weak organizational skills, difficulty filtering out competing stimuli, trouble remembering multiple directions or tasks, language and communication problems, and social awkwardness. Each of these difficulties are characteristic of both ASD and ADHD.

Communication Impairments

Adults with ADHD and those with Autism Spectrum Disorder have great difficulty with literal interpretation of language. Dr. Lorna Wing, who coined the term “Asperger’s” cites the case of a boy who was told to dry a teapot on the outside. He obediently took it outdoors to “wipe it dry.”

People with either ADHD or ASD are able to use language but have trouble comprehending the multiple levels of meaning associated with it. They also share a tendency to talk on and on, ask repetitive questions, and engage in excessive talking and impulsive speech. Consequently, they have trouble listening to others, understanding the needs of others, and forming intimate relationships, all core features of both ADHD and Autism Spectrum Disorder.

Behavioral Deficits

The inability to transition smoothly from one activity to another, a tendency towards stubbornness, frequent temper tantrums, defiance, difficulty compromising, rigidity, and a need for consistency and sameness are some of the behaviors that are characteristic of both ADHD and ASD.

These behaviors have a common source, that being a protective need to avoid being put into situations where lack of communicative skills and social comprehension would risk emotional suffering and social alienation.

Sensory Responses

Adults with Autism Spectrum Disorder often process tactile, visual and auditory stimuli differently. They over- or under respond to environmental stimuli, with unpredictable reactions, such as intolerance of certain sounds, smells and textures.

Yet, it’s also the case that the responses to sensory stimuli common in Autism Spectrum Disorder adults are also true of adults with ADHD. Generally speaking this is an outcome of hypersensitivity and overstimulation, but it involves the same core problem of sensitivity common in people with Autism.

Two Disorders Or One?

When someone diagnosed with ADHD is defiant, asks repetitive questions, overreacts to sensory stimuli, reacts literally, or has trouble planning and executing tasks, we assume the problem is an outcome of impulsivity, inattention or hyperactivity. The same problems with someone diagnosed with Autism Spectrum Disorder are attributed to an inability to comprehend social rules, need for sameness, or failure to form intimate relationships.

In reality, there may not be a distinct difference in what causes these two disorders. They could, instead, be one and the same, both falling on a similar spectrum, differing in degree and severity but essentially the same problem, a consideration opening up new areas for dialogue, research and treatment. 


Dr. Kenneth Roberson

Dr. Kenneth Roberson is an Adult Autism Psychologist in San Francisco with over 30 years of experience. Click below to ask a question or schedule an appointment.

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