Comorbid conditions

A comorbid condition refers to a secondary medical condition that coexists in an individual alongside another distinct primary medical condition. Research shows that several medical conditions are significantly more prevalent in autistic individuals than in the general population (Mann & McKeithan, 2024). The presence of these conditions can affect the effectiveness of interventions or therapies and is therefore important to recognize (Mann & McKeithan, 2024). Some of these conditions are detailed below.

Attention Deficit Hyperactivity Disorder

Chronic condition marked by persistent inattention, hyperactivity, and sometimes impulsivity
Prevalence - Approximately 66% of autistic adults show symptoms of ADHD in adulthood

Subtypes

Based on symptom constellations, ADHD is classified into two subtypes:

ADHD (inattention)

Short attention span
Forgetfulness
Carelessness
Low endurance on tasks that are time-consuming
Inability to carry out instructions
Constant task-switching
Difficulty organizing tasks

ADHD (hyperactivity and impulsiveness)

Inability to sit still, especially in calm or quiet surroundings
Constant fidgeting
Lack of concentration
Excessive physical movement
Difficulty awaiting turn
Tendency to interrupt conversations
Thoughtless action
Lack of a sense of danger

Anxiety is a normal and often adaptive response to stress and perceived threats. The physiological symptoms of anxiety in an individual can alert them to potential dangers and motivate them to take action. But anxiety when triggered in excessive intensity or frequency can be maladaptive. Anxiety disorders are a group of medical conditions characterized by excessive worry, fear or nervousness that significantly impact a person's life. About 40-60% of autistic children also have anxiety disorders (Mann & McKeithan, 2024).

Types of Anxiety Disorders

Based on the specific symptoms and patterns of anxiety experienced by individuals, anxiety disorders are classified into subtypes. The following subtypes of anxiety disorders are known to be prevalent in autistic individuals.

Generalized anxiety disorder (GAD) - persistent and excessive worry over a number of different things
Social anxiety disorder - intense anxiety or fear of being judged, negatively evaluated, or rejected in a social or performance situation
Obsessive compulsive disorder (OCD) - characterized by repetitive and compulsive behaviors believed to be a means of coping with undesirable and compulsive thoughts. This can be hard to diagnose in autistic individuals since they may engage in repetitive behaviors for other reasons.

Gastrointestinal (GI) disorders are medical conditions that affect the digestive system, which includes the esophagus, stomach, small intestine, large intestine (colon), rectum and anus.
the most common GI disorders affecting autistic individuals are chronic constipation, abdominal pain, diarrhea and fecal incontinence. Others include gastro-esophageal reflux disease (GORD) and stomach bloating.
Prevalence - up to 91 % of autistic individuals are expected to also have GI problems (Mann & McKeithan, 2024).
Possible causes - altered gut bacteria, increased gut permeability, longer food transit time through gut, low fiber intake.
No evidence supports the use of gluten-free and casein-free diet to treat GI problems in autistic individuals (Mann & McKeithan, 2024).

Intellectual Disability (ID) is a mental health condition characterized by a below-average measured IQ (70 at six years of age or older) and difficulties with adaptive skills needed for day-to-day living.
Prevalence among autistics - Earlier thought to be as high as 50-60% and now thought to be 30-40% with another 20-25% having borderline ID with an IQ of 71-85 (Mann & McKeithan, 2024).
Skill development both in ID and among autistics may be uneven across skill areas, especially verbal vs non-verbal skills among autistics.
Test taking ability and subject matter might affect the performance of autistic individuals (especially children) on IQ tests.

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Common sleep problems in autistic individuals include trouble falling asleep and staying asleep, nightmares, night terrors and sleepwalking.
Sleep issues worsen behavioral challenges, interfere with learning and decrease overall quality of life.
Prevalence among autistics - As high as 80% of autistic children are reported to have sleep problems (Mann & McKeithan, 2024).
Polysomnography studies of autistic children show that most of their abnormalities relate to rapid eye movement 9REM) sleep (Mann & McKeithan, 2024).
Non-pharmacological treatments for sleep problems include regular bedtime routine, abstaining from caffeine consumption past noon, exercise and sunshine exposure and good sleep hygiene (e.g., absence of distractions like computers and other screens from bedroom)

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Clinical Depression, according to the Centers for Disease Control (CDC) is a mental health condition characterized by a prolonged and severe depressed or sad state of mind that impacts everyday functioning. It is characterized by the following symptoms, among others (Mann & McKeithan):

Attempts to treat low moods with alcohol or drugs
Changes in sleep patterns
Crying
Confusion
Decreased appetite
Decreased interest in activities that used to be pleasurable
Tearfulness
Expressions of decreased self-esteem
Irritability
Reckless behavior
Sudden anger
Suspiciousness about intentions of others
Thoughts of suicide

In the autistic population, depression is more prevalent among those with more severe autism symptoms, older age and higher verbal IQ (Mann & McKeithan):

Epilepsy

Epilepsy is a brain disorder. An individual is diagnosed with epilepsy when they have had two or more seizures (Centers for Disease Control and Prevention [CDC], 2020).

Seizure

A change in normal brain activity that lasts from a few seconds to a few minutes.

Prevalence

About 1.2% of the general US population are expected to be epileptic (CDC, 2020). 20-40% of autistic individuals are expected to be epileptic (Mann & McKeithan, 2024).

Signs

Unexplained staring spells
Involuntary movements
Unexplained confusion
Severe headaches
Sleepiness
Unexplained changes in abilities or emotions

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Rohini Knudson

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