What Is the Correct Diagnostic Formulation In Neuropsychiatric Practice?

A reader responds to Diagnostic Errors in Neuropsychiatry, by Barbara Schildkrout, MD. Dr Schidkrout’s article was part of the July/August 2019 Special Report collection on neuropsychiatry.

LETTER TO THE EDITOR

Dr Schildkrout reviews many of the pitfalls when psychiatrists attempt to arrive at a correct diagnostic formulation in neuropsychiatric practice in particular the timely identification of early  (“prodromal”) manifestations and/or atypical presentations of medical illness which may mimic or contribute to a patient’s psychiatric complaints/symptoms.  She also outlines a useful paradigm for differential diagnosis involving the interplay of System 1 and System 2 cognition.

Relevant to this discussion is the important role that psychological/neuropsychological testing can play in clarifying a patient’s neuropsychiatric status.

While psychologists who test psychiatric patients are clearly not immune to many of the cognitive biases cited in this article, the measurement-based data generated by psychodiagnostic tests can help to attenuate their influence.

Regarding the case vignette of Mr O with a suspected Parkinsonian syndrome, testing can, in the context of the history and the findings from the office-based mental status examination, quickly and reliably identify possible deficits which are consistent with such a working hypothesis: Slowed information processing speed and evidence of subtle tremor and/or micrographia; visuo-cognitive difficulties compatible with a possible diagnosis of mild neurocognitive disorder with Lewy bodies dementia, and so on. Testing can also address the issue of a possible somatization component via well-validated profiles derived from tests like the MMPI-2 and a sleep disorder profile germane to REM sleep behavior disorder based on self-report instruments like the Neurodegenerative Disease Sleep Questionnaire/NDSQ and REM Sleep Behavior Disorder Questionnaire/RBDSQ.

Jerrold Pollak, PhD
Portsmouth, NH