A 10-year-old boy displays deficits in intellectual functions that involve his ability to reason, solve problems, and learn from instruction or experience. Although he has been slow to develop skills in school and is behind his peers in reading, writing, and mathematical abilities, he is slowly making progress. As a result of his delays, he has significant impairments in his ability to develop socially appropriate interpersonal communication skills and has developed no real friendships. He is dependent on others for assistance with his basic needs, such as dressing and feeding. What is the appropriate severity rating for this patient's presentation?

Choice A reason: Mild intellectual disability typically involves delays in academic skills and some dependence on adults but allows for relatively independent functioning in daily life. This patient’s significant impairments in self-care and social skills exceed mild severity. Choice B reason: Moderate intellectual disability usually involves noticeable delays in academic and social skills with some assistance required for self-care. The extent of this patient’s dependency on others and lack of friendships exceeds moderate severity. Choice C reason: This is correct. Severe intellectual disability is characterized by marked impairments in intellectual functioning and adaptive behavior, requiring extensive support for daily living, including basic self-care, and often involves very limited social interactions. The patient’s profile fits these criteria. Choice D reason: Although an IQ score is informative, severity ratings also consider adaptive functioning. The detailed description of the patient’s social and self-care deficits allows determination of severity without a formal IQ score.