Certified Developmental Disabilities Nurse (CDDN) Practice Exam 2026
| 200 Questions with Answers & Rationales | DDNA Certification Test
Bank – Verified A+ Study Guide
Question 1
A 24-year-old individual with severe intellectual disability and non-
verbal autism begins slapping their head repeatedly and screaming.
What should be the developmental disabilities nurse’s priority initial
assessment?
• A. Conduct a functional behavior assessment (FBA) to identify
environmental triggers.
• B. Assess for physical distress, illness, or acute pain (e.g., ear
infection, dental abscess).
• C. Administer a PRN dose of an ordered antipsychotic medication.
• D. Place the individual in a quiet room using physical restraints.
Correct Answer: B. Assess for physical distress, illness, or acute pain
(e.g., ear infection, dental abscess).
Detailed Rationale: Individuals with severe communication
impairments often express acute physical pain or medical distress
through sudden behavioral changes or self-injurious behavior (SIB).
Medical causes (such as toothaches, otitis media, constipation, or
urinary tract infections) must always be ruled out before attributing
behavioral changes solely to psychiatric or environmental causes.
Question 2
Which condition is the most common genetic cause of inherited
intellectual disability?
, • A. Down Syndrome
• B. Fragile X Syndrome
• C. Prader-Willi Syndrome
• D. Fetal Alcohol Spectrum Disorder
Correct Answer: B. Fragile X Syndrome
Detailed Rationale: Fragile X syndrome is the most common inherited
genetic cause of intellectual disability. Down syndrome is the most
common genetic cause overall, but it is typically caused by a random
non-disjunction error (Trisomy 21) rather than direct inheritance.
Question 3
A client with Prader-Willi Syndrome lives in a residential group home.
Which intervention is essential to include in the client's daily plan of
care?
• A. Offering an unrestricted, self-directed diet to promote
autonomy.
• B. Securing food pantries and kitchens to prevent uncontrolled
food access.
• C. Monitoring strictly for high risk of chronic diarrhea and
malabsorption.
• D. Administering high-calorie nutritional supplements between
meals.
Correct Answer: B. Securing food pantries and kitchens to prevent
uncontrolled food access.
,Detailed Rationale: Prader-Willi Syndrome is characterized by
hyperphagia (an insatiable appetite) due to hypothalamic dysfunction.
Without strict environmental controls, such as locking kitchens and food
storage areas, individuals are at extreme risk for life-threatening
obesity, gastric rupture, and choking.
Question 4
An adult with Down syndrome who is 45 years old shows a gradual
decline in memory, loss of adaptive living skills, and newly emerging
confusion. What condition should the CDDN suspect?
• A. Early-onset Alzheimer's disease
• B. Normal aging process
• C. Major Depressive Disorder
• D. Schizophrenia
Correct Answer: A. Early-onset Alzheimer's disease
Detailed Rationale: Individuals with Down syndrome have an extra copy
of chromosome 21, which carries the gene for the amyloid precursor
protein (APP). Consequently, nearly all adults with Down syndrome
develop neuropathological changes of Alzheimer's disease by age 40,
with clinical dementia symptoms frequently manifesting in their 40s or
50s.
Question 5
When assessing a client with Cerebral Palsy who presents with severe
spasticity in the lower extremities, which class of medication is most
commonly prescribed to relieve muscle hypertonicity?
, • A. Anticonvulsants (e.g., Phenytoin)
• B. Muscle relaxants / GABA agonists (e.g., Oral or Intrathecal
Baclofen)
• C. Antipsychotics (e.g., Haloperidol)
• D. Anticholinergics (e.g., Atropine)
Correct Answer: B. Muscle relaxants / GABA agonists (e.g., Oral or
Intrathecal Baclofen)
Detailed Rationale: Baclofen is a GABA-B agonist that acts on the spinal
cord to reduce spasticity and muscle spasms in conditions like spastic
cerebral palsy. It can be administered orally or via an intrathecal
baclofen pump (ITB).
Question 6
A client with Down syndrome is undergoing pre-operative evaluation
prior to participating in a high-impact adaptive sports program. Which
diagnostic screening is critical to perform?
• A. Cervical spine X-rays to assess for Atlantoaxial Instability (AAI)
• B. Lumbar puncture to assess cerebrospinal fluid pressure
• C. Bone density scan (DEXA) for lower extremities
• D. Serum uric acid level
Correct Answer: A. Cervical spine X-rays to assess for Atlantoaxial
Instability (AAI)
Detailed Rationale: Atlantoaxial instability (laxity of the C1–C2 joint)
occurs in approximately 10% to 20% of individuals with Down
| 200 Questions with Answers & Rationales | DDNA Certification Test
Bank – Verified A+ Study Guide
Question 1
A 24-year-old individual with severe intellectual disability and non-
verbal autism begins slapping their head repeatedly and screaming.
What should be the developmental disabilities nurse’s priority initial
assessment?
• A. Conduct a functional behavior assessment (FBA) to identify
environmental triggers.
• B. Assess for physical distress, illness, or acute pain (e.g., ear
infection, dental abscess).
• C. Administer a PRN dose of an ordered antipsychotic medication.
• D. Place the individual in a quiet room using physical restraints.
Correct Answer: B. Assess for physical distress, illness, or acute pain
(e.g., ear infection, dental abscess).
Detailed Rationale: Individuals with severe communication
impairments often express acute physical pain or medical distress
through sudden behavioral changes or self-injurious behavior (SIB).
Medical causes (such as toothaches, otitis media, constipation, or
urinary tract infections) must always be ruled out before attributing
behavioral changes solely to psychiatric or environmental causes.
Question 2
Which condition is the most common genetic cause of inherited
intellectual disability?
, • A. Down Syndrome
• B. Fragile X Syndrome
• C. Prader-Willi Syndrome
• D. Fetal Alcohol Spectrum Disorder
Correct Answer: B. Fragile X Syndrome
Detailed Rationale: Fragile X syndrome is the most common inherited
genetic cause of intellectual disability. Down syndrome is the most
common genetic cause overall, but it is typically caused by a random
non-disjunction error (Trisomy 21) rather than direct inheritance.
Question 3
A client with Prader-Willi Syndrome lives in a residential group home.
Which intervention is essential to include in the client's daily plan of
care?
• A. Offering an unrestricted, self-directed diet to promote
autonomy.
• B. Securing food pantries and kitchens to prevent uncontrolled
food access.
• C. Monitoring strictly for high risk of chronic diarrhea and
malabsorption.
• D. Administering high-calorie nutritional supplements between
meals.
Correct Answer: B. Securing food pantries and kitchens to prevent
uncontrolled food access.
,Detailed Rationale: Prader-Willi Syndrome is characterized by
hyperphagia (an insatiable appetite) due to hypothalamic dysfunction.
Without strict environmental controls, such as locking kitchens and food
storage areas, individuals are at extreme risk for life-threatening
obesity, gastric rupture, and choking.
Question 4
An adult with Down syndrome who is 45 years old shows a gradual
decline in memory, loss of adaptive living skills, and newly emerging
confusion. What condition should the CDDN suspect?
• A. Early-onset Alzheimer's disease
• B. Normal aging process
• C. Major Depressive Disorder
• D. Schizophrenia
Correct Answer: A. Early-onset Alzheimer's disease
Detailed Rationale: Individuals with Down syndrome have an extra copy
of chromosome 21, which carries the gene for the amyloid precursor
protein (APP). Consequently, nearly all adults with Down syndrome
develop neuropathological changes of Alzheimer's disease by age 40,
with clinical dementia symptoms frequently manifesting in their 40s or
50s.
Question 5
When assessing a client with Cerebral Palsy who presents with severe
spasticity in the lower extremities, which class of medication is most
commonly prescribed to relieve muscle hypertonicity?
, • A. Anticonvulsants (e.g., Phenytoin)
• B. Muscle relaxants / GABA agonists (e.g., Oral or Intrathecal
Baclofen)
• C. Antipsychotics (e.g., Haloperidol)
• D. Anticholinergics (e.g., Atropine)
Correct Answer: B. Muscle relaxants / GABA agonists (e.g., Oral or
Intrathecal Baclofen)
Detailed Rationale: Baclofen is a GABA-B agonist that acts on the spinal
cord to reduce spasticity and muscle spasms in conditions like spastic
cerebral palsy. It can be administered orally or via an intrathecal
baclofen pump (ITB).
Question 6
A client with Down syndrome is undergoing pre-operative evaluation
prior to participating in a high-impact adaptive sports program. Which
diagnostic screening is critical to perform?
• A. Cervical spine X-rays to assess for Atlantoaxial Instability (AAI)
• B. Lumbar puncture to assess cerebrospinal fluid pressure
• C. Bone density scan (DEXA) for lower extremities
• D. Serum uric acid level
Correct Answer: A. Cervical spine X-rays to assess for Atlantoaxial
Instability (AAI)
Detailed Rationale: Atlantoaxial instability (laxity of the C1–C2 joint)
occurs in approximately 10% to 20% of individuals with Down
