The neurologic examination in adult psychiatry: from soft signs to hard science.

Of the proliferating approaches to neuropsychiatric assessment, a relatively neglected technique is the venerable, accessible, noninvasive, and inexpensive neurologic examination. This article organizes and synthesizes the literature on neurological findings in adult psychiatric patients. Problems in conducting and interpreting research in this area are examined, clinically pertinent empirical findings are surveyed, and directions for future investigation are outlined. Most of the "soft signs" can be reliably evaluated, and many have been validated against other techniques. Several psychiatric diagnoses are associated with impaired neurologic performance. Prognosis and treatment selection may also be informed by neurologic findings. The neurologic exam should be regarded as a collection of neurobiologic probes rather than as a single irreducible variable. Future work must better establish interrater and test-retest reliability of individual elements of the neurologic exam in psychiatric populations and focus on developing the clinical utility of individual and combined elements of the neurologic exam.