When Aggression Is a Symptom
…Not a Behavior
Summary: Aggression in individuals with IDD or autism is frequently a symptom of underlying medical or neurological conditions rather than solely a behavioral issue, often overlooked due to “diagnostic overshadowing.” Key contributors include medication side effects, unrecognized focal seizures, and intense panic or anxiety responses. Shifting focus to these underlying causes, rather than treating aggression solely with behavioral approaches, is essential for proper care.
Aggression is one of the most common reasons that a person with intellectual and developmental disabilities (IDD) or autism spectrum disorder (ASD) is referred for medical or psychiatric evaluation. Many causes of aggression are behavioral or environmental and may include victimization, attempts to escape demands, disruption of routines or rituals, difficulty communicating needs, or expressions of pain or distress that cannot easily be verbalized. When triggers can be identified, these situations are often addressed through environmental modification, communication supports, and behavioral interventions.
However, aggression is sometimes not primarily a behavior — it may represent a symptom or direct manifestation of an underlying medical or neurologic condition. In such cases, there may be no clear environmental precipitant. Several medical conditions commonly seen in individuals with IDD and ASD can present in this way and may be diagnosed and treated medically when accurate histories are obtained from caregivers and observers.
Diagnostic Overshadowing: An Important Clinical Risk
A major barrier to recognizing medical causes of aggression is diagnostic overshadowing — the tendency to attribute new or worsening symptoms solely to a person’s disability, psychiatric history, or behavioral presentation rather than considering underlying medical or neurologic conditions.
When diagnostic overshadowing occurs, clinicians and caregivers may unintentionally overlook important warning signs such as sudden changes in personality, alterations in consciousness, pain, medication effects, or emerging neurologic symptoms. Aggression may then be treated primarily with behavioral or psychotropic approaches while the underlying cause remains unrecognized.
A person-centered and medically informed evaluation should ask:
What has changed from this individual’s baseline?
Could this behavior represent discomfort, confusion, anxiety, or neurologic change?
Are there medical, sensory, or environmental contributors requiring assessment?
Avoiding diagnostic overshadowing improves diagnostic accuracy, reduces unnecessary medication exposure, and promotes equitable healthcare for people with IDD and ASD.
Medication Effects and Metabolic Changes
One potential cause of sudden or unexplained aggression is toxic, metabolic, or adverse effects related to medications, including medication interactions. Many medications can contribute to confusion, irritability, or behavioral dysregulation. Caregivers may describe this as a noticeable change in personality — for example, “they just aren’t themselves.”
Examples may include:
Sedating or anticholinergic medications such as diphenhydramine.
Benzodiazepines (e.g., lorazepam or alprazolam), which may cause disinhibition in some individuals.
Selective serotonin reuptake inhibitors (SSRIs) or serotonin–norepinephrine reuptake inhibitors (SNRIs) when activating or poorly tolerated.
Elevated serum levels of antiseizure medications may also contribute to confusion or agitation. Lithium toxicity can produce irritability, cognitive changes, and renal dysfunction leading to metabolic imbalance with resulting confusion and/or irritability.
When medication toxicity is suspected, clinicians may obtain laboratory studies, including medication levels. Trough levels — blood samples drawn before the morning dose — are often most informative.
Seizures Misinterpreted as Aggression
Another cause of apparently unprovoked aggression may be focal impaired awareness seizures (formerly called complex partial seizures).
Many people recognize generalized tonic-clonic seizures, which involve loss of consciousness and convulsive movements. In contrast, focal seizures may be subtle and frequently overlooked.
Possible features include:
Aura: a sensory warning such as visual disturbances or unusual smells.
Brief alteration in awareness or responsiveness.
Subtle motor movements or head turning that may be easily missed.
Following the seizure, a person may experience disorientation, fear, confusion, or agitation. Observers may interpret this as aggression, particularly when the individual attempts to run away or strike out due to confusion.
Key clues suggesting seizure-related behavior include lack of environmental triggers, brief periods of apparent absence, and post-episode confusion or fatigue. Caregivers may have noted and can report or, if asked, confirm these observations.
Panic and Anxiety-Related Responses
Aggression may also occur during episodes of panic or severe anxiety, which are common co-occurring conditions in people with autism spectrum disorder. Unlike seizures, panic episodes do not involve a change in level of consciousness. Instead, the individual experiences overwhelming fear or physiologic arousal. Behavioral responses may include fight, flight, or freeze.
Potential triggers include unexpected changes in routine, sensory overstimulation, or stressful transitions. Some individuals demonstrate early warning signs of escalating anxiety, such as pacing or increased motor activity. Observable physical signs of panic include tachycardia, tachypnea, flushing or pallor, and diaphoresis. These physiologic responses reflect activation of the autonomic nervous system and should not be mistaken for simply the result of physical exertion.
The Role of Caregivers and Clinicians
Healthcare professionals familiar with these medical contributors to aggression often ask caregivers detailed questions about behavioral patterns, physical signs, and timing of episodes (caregivers may report tachypnea as “hyperventilation” and diaphoresis as “heavy sweating).” Caregivers who understand these possibilities can provide essential observations that help guide diagnosis and treatment.
Recognizing aggression as a potential medical symptom — rather than solely a behavioral issue — helps reduce diagnostic overshadowing and leads to more accurate assessment, safer care, and improved outcomes for individuals with intellectual and developmental disabilities and autism spectrum disorder.
About the Authors
Dr. Seth M. Keller is a board-certified neurologist and Fulbright Specialist with Neurology Associates of South Jersey specializing in neurologic, aging, and dementia care for adults with intellectual and developmental disabilities (IDD). He is internationally recognized for advancing inclusive health through medical education, workforce training, and interdisciplinary collaboration. Dr. Keller is Past President of the American Academy of Developmental Medicine and Dentistry, Co-President of the National Task Group on Intellectual Disabilities and Dementia Practices, and founder of the Adult IDD Section of the American Academy of Neurology. He works globally with universities and health systems to strengthen IDD curriculum development, dementia care models, and sustainable training initiatives.
Andrew Levitas, M.D, is retired Professor of Psychiatry and Medical Director of the Center of Excellence for Mental Health Treatment for Persons with Intellectual Disabilities and Autism Spectrum Disorders of the Department of Psychiatry, Rowan University-SOM. He is a graduate of the Albert Einstein College of Medicine, Bronx, New York, did his residency in Psychiatry at Downstate/Kings County Hospital Center, Brooklyn, New York, and his Fellowship in Child Psychiatry at the University of Colorado Health Sciences Center, Denver, Colorado. Dr. Levitas is Board Certified in both Psychiatry and Child Psychiatry. He is the 1999 recipient of the Robert D. Sovner Award for psychiatric services to persons with intellectual disabilities.