While there is not a single behavioral or communication test that can detect Autism, several Autism-specific tools are now being used for a formal diagnosis. These include the Autism Diagnostic Observation Schedule, Second Edition (ADOS™-2), the Autism Diagnostic Interview (ADI), the Screening Tool for Autism in Toddlers (STAT), the Childhood Autism Rating Scales (CARS), and the Tele-ASD-Peds for diagnosis for use in telehealth. All of these tests should be used as part of a larger assessment, and not just on their own, as the determination of Autism is best completed with multiple sources of information.

Oftentimes, individuals diagnosed with Autism also have other conditions that impact their development and functionality. It is important for you to share your concerns with your doctor so that they can properly assess the symptoms and provide the individual with appropriate medical treatment.

Chronic Constipation and/or Diarrhea

Medical literature states that about 47 percent of adults who experience Autism and 45 percent of children with Autism have gastrointestinal symptoms. Diarrhea is most common, followed by abdominal pain and constipation. Constipation in people with Autism is usually not hard, impacted stools, but the slow passage of stools with long gaps in between, and loose stools when they do come.

IQ Concerns

Research studies have frequently used inappropriate IQ tests, such as verbal tests with nonverbal individuals, and in some cases have estimated intelligence level without any objective evidence. Tests that do not require language skills, such as the Test of Nonverbal Intelligence (TONI), can offer more accurate information about the person.

Immune & GI Systems

Increasing evidence shows that gastrointestinal (GI) symptoms, such as gastrointestinal disruption, abdominal pain, diarrhea, constipation, and flatulence, has been characterized as a common comorbidity in patients with ASD, ranging between 9 and 84% depending on the studies being retrospective or prospective (Wasilewska and Klukowski, 2015), and are linked to the severity of ASD symptoms (Adams et al., 2011; Gorrindo et al., 2012; Chaidez et al., 2014).

Low Muscle Tone

About 30 percent of children with Autism have moderate to severe loss of muscle tone, which can limit their gross and fine motor skills.


Some people with Autism have very high pain thresholds (insensitivity to pain), while others have very low pain thresholds. There are interventions, such as sensory integration therapy, designed to help increase reliability of their sensory processing and integration.


About 30 percent of children with Autism have moderate to severe pica, a compulsive eating-disorder characterized by eating non-food items such as paint, sand, dirt, paper, etc. Pica can be dangerous as ingesting these inedible substances can cause choking, digestive problems, parasitic infections, and other illnesses.


It is estimated that around 30 percent of people with Autism develop epilepsy, some in early childhood and others as they go through hormone level changes in puberty. Suspected seizures should be confirmed by electroencephalogram (EEG) and treated with prescribed anticonvulsant medications.

Sensory Problems

The diagnosis of Autism includes atypical responses to sounds, sights, touch, taste and smells. High-pitched intermittent sounds, such as fire alarms or school bells, may be painful for people with Autism. Scratchy fabrics and clothing tags may also be intolerable, and some people have visual sensitivities, such as the flickering of fluorescent lights.

These are only a few examples of sensory experiences. Sensory needs can range in severity and change over time. Consult an occupational therapist for support in evaluating and supporting sensory processing and integration.

Sleep Problems

Many people who experience Autism have sleep challenges. Night waking may be due to gastrointestinal issues, allergies, environmental intolerances, seizures or the effects of medications. Other potential causes are sleep apnea (pauses in breathing when the airway becomes obstructed during sleep), sleep terrors or confusional arousals. Individuals with sensory processing difficulties may have more problems falling asleep and increased periods of night waking.


Infant and toddler diagnosis begin with voicing your concerns with your child’s pediatrician or primary care doctor. A primary care professional should be able to review your child’s development and conduct a short Autism screening. If that screening indicates that Autism might be a possibility, the doctor may diagnose your child if they have training, especially if Autism characteristics are clearly present. If they do not have Autism-specific training, or if your child’s presentation is subtle or complicated by other factors, they may refer you to an Autism specialist.

Most Autism diagnosticians will not diagnose a child until they are at least one-year-old. However, if your child has delays, you can seek services before that diagnosis, often from early intervention federal programs, or from private speech, occupational therapy, or physical therapy clinics. Your primary care professional can give a referral to early intervention or private therapists.

Once your child is at least one-year-old, an Autism diagnostician (developmental pediatrician, child psychologist, child psychiatrist) can begin to explore evaluating them. The evaluation will consist of interviews with you, review of records, and an observation of or interaction with your child. See the section on Medical Diagnosis for more information.