Adults With Developmental Disabilities

Introduction

In the context of MCCQE1 preparation, understanding the care of adults with Intellectual and Developmental Disabilities (IDD) is crucial. As the life expectancy of individuals with IDD increases, Canadian physicians—particularly in Family Medicine and Psychiatry—are increasingly responsible for their care.

The Canadian healthcare system emphasizes a community-based model of care, moving away from institutionalization. This shift places the onus on primary care providers to manage complex physical and mental health needs.

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Definition: Developmental disabilities are a group of conditions due to an impairment in physical, learning, language, or behavior areas. These conditions begin during the developmental period (before age 18 in Canada), may impact day-to-day functioning, and usually last throughout a person’s lifetime.

MCCQE1 Objectives and CanMEDS Framework

For the MCCQE1, candidates must demonstrate the ability to assess and manage adults with IDD, specifically focusing on:

Communicator: Adapting communication strategies for patients with varying levels of verbal and cognitive ability.
Medical Expert: Differentiating between behavioral manifestations of physical illness vs. primary psychiatric disorders.
Health Advocate: Recognizing the vulnerability of this population to abuse and systemic healthcare disparities.

Epidemiology and Etiology in Canada

Approximately 1% to 3% of the Canadian population has a developmental disability. The etiology is diverse, and understanding the cause can guide surveillance for comorbidities.

Common Etiologies

Category	Examples	Canadian Context Notes
Chromosomal	Down Syndrome (Trisomy 21), Fragile X Syndrome	Down syndrome is the most common chromosomal cause of ID.
Environmental	Fetal Alcohol Spectrum Disorder (FASD)	FASD is the leading known cause of preventable developmental disability in Canada.
Perinatal	Hypoxic-ischemic encephalopathy, Prematurity	Improvements in Canadian NICU care have increased survival but also morbidity.
Genetic/Metabolic	Phenylketonuria (PKU), Prader-Willi Syndrome	Universal newborn screening in Canada detects many metabolic causes early.

Clinical Assessment: The “HELP” Framework

When an adult with IDD presents with a change in behavior, it is a medical emergency until proven otherwise. The baseline assumption should never be “it’s just part of their disability.”

Use the HELP framework to guide your differential diagnosis. This is a high-yield concept for the MCCQE1.

Step 1: H - Health

Rule out medical causes first. Patients with IDD often have a high pain threshold or cannot localize pain.

Common culprits: Dental abscess, constipation, UTI, GERD, fracture, medication side effects.
The “Fatal Four” in IDD: Aspiration, Constipation/Bowel Obstruction, Dehydration, Seizures.

Step 2: E - Environment

Assess for changes in the patient’s support system or physical environment.

Staff changes, roommate conflicts, change in routine, lack of privacy, under-stimulation or over-stimulation.

Step 3: L - Lived Experience

Consider emotional and psychological stressors.

Grief (loss of a parent/caregiver), history of trauma or abuse, frustration with communication limitations.

Step 4: P - Psychiatric Disorder

Only after ruling out H, E, and L, consider a primary psychiatric diagnosis.

Prevalence of psychiatric disorders is 2-3x higher in the IDD population than the general population.

Psychiatric Comorbidities and Diagnostic Challenges

Diagnosing psychiatric conditions in this population is challenging due to Diagnostic Overshadowing.

Key Concept: Diagnostic Overshadowing

This occurs when a healthcare professional attributes a patient’s symptoms (e.g., aggression, withdrawal) solely to their developmental disability, thereby missing a treatable comorbid condition (e.g., depression, anxiety, or a physical illness like a UTI).

Behavioral Phenotypes

Certain syndromes have characteristic behavioral associations relevant to MCCQE1 questions.

Down Syndrome

Down Syndrome (Trisomy 21):

Early-onset Alzheimer’s Disease (onset often age 40-50).
Depression (often presents as vegetative symptoms/withdrawal).
Hypothyroidism (mimics depression).

Management Strategies

Management must be multimodal, adhering to the Bio-Psycho-Social model.

1. Non-Pharmacological (First Line)

Communication: Use plain language, visual aids, and involve caregivers/Substitute Decision Makers (SDM).
Environmental modification: Reduce noise, establish routine.
Behavioral therapy: Positive behavioral support.

2. Pharmacological

Medication should be used for treating a diagnosed psychiatric disorder, not merely for “behavior control.”

Start Low, Go Slow: Patients with IDD are often more sensitive to side effects (e.g., EPS from antipsychotics, disinhibition from benzodiazepines).
Monitoring: Metabolic monitoring is crucial if antipsychotics are used (CanMEDS Medical Expert).

3. Legal and Ethical (Canadian Context)

Consent: Assess capacity for the specific decision. Having an IDD does not automatically mean a lack of capacity.
Substitute Decision Maker (SDM): If the patient lacks capacity, obtain consent from the appropriate SDM as per provincial legislation (e.g., Health Care Consent Act in Ontario).

Canadian Guidelines

The 2018 Canadian Consensus Guidelines on Primary Care for Adults with Intellectual and Developmental Disabilities are the gold standard for practice.

Key Guideline Recommendations:

Annual Health Check: Every adult with IDD should have a comprehensive annual physical exam (periodic health review).
Polypharmacy: Regular medication review to reduce anticholinergic burden and inappropriate psychotropics.
Screening:
- Vision/Hearing: Screen every 5 years (high risk of sensory impairment).
- Cervical Cancer: Same as general population, though often neglected.
- Breast Cancer: Same as general population.

Study Checklist for Management

Use this checklist to ensure a comprehensive approach:

Rule out physical causes (constipation, dental, pain).
Review medications for side effects or interactions.
Assess environment and supports.
Establish capacity for decision-making.
Involve caregivers as partners in care.
Start medications at low doses if indicated.

Key Points to Remember for MCCQE1

Behavior = Communication. A sudden change in behavior is a medical emergency (delirium/pain) until proven otherwise.
Diagnostic Overshadowing. Do not assume symptoms are “just the disability.”
Consent. Always assume capacity first; assess capacity specifically for the decision at hand.
FASD. The most common preventable cause of developmental disability in Canada.
Aging. Adults with Down syndrome are at very high risk for early-onset Alzheimer’s dementia.

Sample Question

Case Presentation

A 28-year-old man with Down syndrome is brought to the emergency department by his group home staff. He has been non-verbal at baseline but generally cooperative and cheerful. Over the past 48 hours, he has become agitated, is hitting his head against the wall, and refuses to eat. He has no known history of psychiatric illness. His vital signs are: Temperature 37.8°C, BP 130/85 mmHg, HR 102 bpm, RR 18/min.

Question

Which one of the following is the most appropriate initial step in the management of this patient?

A. Administer haloperidol 5 mg IM for agitation
B. Refer immediately to psychiatry for new-onset psychosis
C. Perform a comprehensive physical examination and basic metabolic workup
D. Initiate a trial of an SSRI for probable depression
E. Increase behavioral support staffing at the group home

Explanation

The correct answer is:

C. Perform a comprehensive physical examination and basic metabolic workup

Detailed Explanation

This scenario represents a classic “diagnostic overshadowing” trap. The patient presents with an acute change in behavior (agitation, self-injurious behavior, anorexia). In patients with developmental disabilities, acute behavioral changes are most often due to physical illness, pain, or environmental stressors (The HELP framework).

Option C is correct: The patient has a low-grade fever and tachycardia, suggesting a possible underlying infection or physical process (e.g., dental abscess, urinary tract infection, constipation/obstruction). A thorough physical exam and workup are required to rule out medical causes (“H” in HELP) before considering psychiatric causes.
Option A is incorrect: Chemical restraint should be a last resort for imminent safety risks and does not address the underlying cause. 5 mg is also a high starting dose for this population.
Option B is incorrect: Referring to psychiatry without medical clearance is inappropriate. “New-onset psychosis” is a diagnosis of exclusion.
Option D is incorrect: While depression is common in Down syndrome, the acuity (48 hours) and autonomic signs (tachycardia, fever) point to a medical cause.
Option E is incorrect: Behavioral support is part of long-term management but does not address the acute medical urgency.

References

Sullivan, W. F., et al. (2018). Primary care of adults with intellectual and developmental disabilities: 2018 Canadian consensus guidelines. Canadian Family Physician, 64(4), 254-279. Link
Medical Council of Canada. (n.d.). MCCQE Part I Objectives: Mental Health.
Centre for Addiction and Mental Health (CAMH). (2023). Intellectual and Developmental Disabilities. Toronto, Canada.
Grier, E., et al. (2018). Health checks for adults with intellectual and developmental disabilities. Canadian Family Physician.