Special Diagnostic Considerations with Clients Who Have Developmental Disabilities


1. Their thought process are usually very concrete. Responses to common mental status questions may sound very bizarre because of the client’s concrete interpretations.


2. Their concrete thought processes make the use of projective assessment techniques such as the Rorschach and TAT ineffective in identifying pathology.


3. If the client has sufficiently high verbal skills, sometimes the MMPI-2 or A can be helpful, if interpreted conservatively. Use of audio tapes is recommended, even if the reading level seems sufficient, as the multisensory input often improves comprehension of the questions.


4. People with developmental disabilities often share the following thought processes:

a. difficulty with fluidity and flexibility of thinking,

b. a dislike of ambiguity (black and white thinkers),

c. a tendency to concentrate on one aspect of a situation while neglecting other aspects,

d. difficulty prioritizing and breaking down tasks into manageable projects,

e. a tendency to have highly focused areas of expertise and interests, e.g., beets, weather, sports, statistics, phone numbers, dates, and so on,

f. a tendency for poor generalization skills—a person belongs in one and only one

environment—and utilization of a skill in one situation but not others.


5. People with developmental disabilities often share the following communication problems and social issues:

a. idiosyncratic speech,

b. inability to perceive social cues,

c. difficulty utilizing or understanding nonverbal communication well,

d. frequent miscommunications and misunderstandings,

e. a tendency toward one-sided conversations,

f. a tendency to ask many questions, especially when uncomfortable with a


g. a tendency to return to familiar, rote questions, or subjects of personal interest when


h. intrusive behavior,

i. an ability to pretend to be normal,

j. a poor understanding of the impact of behavior on others, and

k. difficulty making and keeping friends.

6. People with developmental disabilities may also have the following miscellaneous issues:

a. special talents, including memory for facts, artistic talents, and unique insights

(Albert Einstein, Temple Grandin);

b. difficulty with change, especially unexpected changes, including

i. anticipatory anxiety and

ii. continued use of a familiar plan even if it doesn't work;

c. significant anxiety in many situations, which may present as agitation, acting out,

worry, perseveration, or obsessive-compulsive behaviors, often with the following


i. responses when anxious tend to be highly predictable,

ii. even though the pattern is predictable, it may be hard to see when the

anxiety is high, and

iii. the acting out may be chaotic;

d. difficulty with Impulse control, particularly when frustration, anxiety, or tension builds

until behavioral acting out occurs.

Avrin, S., Charlton, M., & Tallant, B. (1998). Diagnosis and treatment of clients with developmental disabilities. Unpublished manuscript,  Aurora Mental Health Center as cited in Charlton, M., Kliethermes, M., Tallant,B., Taverne, A., & Tishelman, A. (2004). National Child Traumatic Stress Network: Facts on Traumatic Stress and Children with Disabilities  http://www.nctsn.org/sites/default/files/assets/pdfs/traumatic_stress_developmental_disabilities_final.pdf