Applying the developmental perspective in the psychiatric assessment and diagnosis of persons with intellectual disability: part II--diagnosis.

Dosen (2005) wrote a think-piece, not an experiment. The author asked: what happens if we add a developmental lens to regular DSM labels when the client also has intellectual disability?

The paper walks clinicians through a second layer of questions. It wants you to score where the person sits on communication, social, and daily-living milestones, then fold that map into the psychiatric diagnosis.

There are no numbers. The takeaway is conceptual: a plain DSM diagnosis alone hides why the client shows the behaviors. Adding developmental level explains the form, frequency, and triggers of psychiatric symptoms.

Example: self-injury in someone at a 2-year play level may be frustration from not being understood, not major depression. The same topography at a 10-year level may signal mood disorder.

Einfeld et al. (1995) leveled the same complaint a decade earlier. That review said DSM categories simply lack validity for people with ID and urged clinicians to fold in behavior phenotypes and multivariate data. Dosen (2005) extends the argument by giving a concrete developmental overlay you can use today.

Reiss et al. (1993) also rejected symptom-only labels, but pushed a brain-behavior framework instead. The two papers seem to clash—biological roots versus developmental staging. In practice they are two lenses for the same case: one tells you possible brain systems, the other tells you the client’s current operating level.

Zigler et al. (1989) focused on personality development and warned that life-long dependency shapes presenting problems. Dosen (2005) folds that idea into the diagnostic step, showing how social history and developmental stage intersect with Axis-I conditions.

If you write “major depression” on a treatment plan without noting the client functions at a 4-year level, staff may expect verbal talk therapy and miss sensory-based interventions that fit the developmental stage. Adding one line—Developmental Age: 4 yrs—in the diagnostic summary guides the whole team toward realistic goals, appropriate language, and function-based treatment. Next time you open a case, pair every psychiatric label with the client’s strongest developmental domain scores; your behavior plan will make sense to everyone, including the client.