The three-dimensional approach to neuropsychiatric assessment.

Brain-behavior relationships form the foundation for clinical assessment in neuropsychiatry and behavioral neurology. The complexity of the brain and its clinical disorders makes it important to have a systematic and useful way to apply them. This article introduces the three-dimensional approach to neuropsychiatric assessment (3DA), a process-based approach to integrating brain-behavior relationships into clinical activity. The 3DA is a simple, four-step process for teaching these relationships and their clinical use. The four steps are 1) Explain the principle of localization; first, as applied in general neurology; then, as applied to behavioral neurology and neuropsychiatry; 2) Review brain-behavior relationships in three dimensions: laterality (left-right), anteriority (anterior-posterior), and verticality (cortical-subcortical); 3) Introduce the "frontal-subcortical paradox" (subcortical dysfunction may cause what many know as "frontal lobe" signs) and its explanation (the neurobehavioral correlates of the frontal-subcortical circuits); 4) Present model disorders for the three dimensions. The presentation describes the rationale and approach for using the 3DA to teaching neuropsychiatry and behavioral neurology.