Jeffrey L. Cummings - Neuropsychiatry and Behavioral Neuroscience

All human experience, emotion, motivation, behavior, andactivity are products of brain function. This basic premise underliescontemporary approaches to understanding human behavior and the effectsof brain dysfunction in the clinical discipline of neuropsychiatry.This approach does not deny the important influence of interpersonalrelationships, social and cultural influences, and the modulatinginfluence of the environment on human emotion and behavior; thebrain-based approach acknowledges that all of these environmentalinfluences are mediated through central nervous system (CNS) structuresand function. For every deviant environmental event there will be acorresponding change in CNS function, and when CNS function is alteredthere will be corresponding changes in the behavior or experience ofthe individual.

Neuropsychiatry is theclinical discipline devoted to understanding the neurobiological basis,optimal assessment, natural history, and most efficacious treatment ofdisorders of the nervous system with behavioral manifestations.Neuropsychiatry embraces the rich interplay between the environment andthe nervous system both during the development of the individual andthroughout adulthood and old age. Neuropsychiatrists seek to understandthe disorders of the CNS responsible for abnormal behavior.

This volume presents a contemporary view ofneuropsychiatry and the advances in neuroscience applicable tounderstanding and interpreting human behavior. This introductorychapter summarizes themes and perspectives that provide thephilosophical and clinical framework for the book.

Advances In Neuroscience

The last few decades have seen an incredible advance inneuroscience applicable to neuropsychiatry. Studies in genetics andmolecular biology have revealed mutations that cause majorneuropsychiatric disturbances including familial Alzheimer's disease,familial Parkinson's disease, Huntington's disease, Wilson's disease,and many developmental disorders. Risk genes for some conditions suchas Alzheimer's disease have also been identified. These do not bythemselves cause disease, but they increase the likelihood thatindividuals will express the disorder in the course of their lifetime.Genetic testing, available for many conditions, allows
specific diagnoses or risk assessments and raises important ethicalissues for neuropsychiatry. Identification of a mutation in anasymptomatic individual, for example, reveals critical aspects of hisor her ultimate fate, knowledge not to be taken lightly.

Advances in developmental neurobiology have informed ourunderstanding of congenital malformations of the CNS, many with severeassociated behavioral disturbances. Progress also has been made inunderstanding hyperactivity-attention deficit disorder, autism andpervasive developmental disorders, and childhood epilepsies andmovement disorders. In addition, there has been an evolving integrationof developmental and maturational perspectives to allow a life spanapproach to human neurological disease and neuropsychiatric conditions.Even late-onset disorders such as Alzheimer's disease interact witheducational level and native intellectual abilities to determine thetime of onset and duration of the adult disorder.Comprehensive understanding of any neuropsychiatric illness requires acareful developmental history and integration of life span information.

Advances in neuroimaging have been important in thegrowth of neuropsychiatry. Structural imaging techniques such asmagnetic resonance imaging (MRI) have revealed, for instance, thatwhite matter abnormalities are present in many patients with late-onsetdepressions. The occurrence ofwhite matter disturbances and basal ganglia lesions diminishes thesepatients' responsiveness to pharmacotherapy and increases thelikelihood of confusion following electroconvulsive therapy. 4, 5, Thus, imaging findings have treatment implications and imaging resultsare increasingly incorporated in neuropsychiatric assessment andtreatment planning.

Functional imaging such as positron emission tomography(PET) and single photon emission computed tomography (SPECT) providecritical information about brain function in neuropsychiatric illness.Patients with Alzheimer's disease, for example, have reduced glucosemetabolism in the parietal lobes; when psychosis and agitation arepresent, frontal and anterior temporal hypometabolism is also evident. 7, Positron emission tomography has shown disturbances in frontal lobe activation in patients with schizophrenia, as well as orbitofrontal hypermetabolism in patients with obsessive-compulsive disorder.Functional MRI (fMRI) provides a stress test for the CNS, revealingabnormal patterns of activation in patients with brain disease. Thisapproach may eventually prove sensitive to the earliest changes inincipient neurological conditions. Magnetic resonance spectroscopyprovides information about the chemical composition of brainstructures, reveals abnormalities in individual diseases, and mayprovide a window on CNS concentrations of some therapeutic agents.Magnetic resonance angiography (MRA) allows noninvasive study of thebrain vasculature and MR perfusion studies have shown remarkablesensitivity to the occurrence of recent ischemic brain injury. Togetherthese technologies provide a diverse armamentarium of techniques fordiagnosing CNS disease and understanding their pathophysiology.

Progress in neuropsychology also informs contemporaryneuropsychiatry. There have been substantial advances, for example, inrecognizing and characterizing memory subroutines includingregistration, consolidation, and retrieval.Focal brain lesions and degenerative disorders differentially affectthese processes, depending on the brain structures involved. Similarly,the frontal lobe syndrome has been divided into medial frontal,orbitofrontal, and dorsolateral prefrontal types, andneuropsychological mechanisms mediated by the dorsolateral prefrontalcortex including planning, sequencing, implementing, executing, andmonitoring of behaviors have been identified.Attentional mechanisms, visuospatial processes, and language have beenstudied and the results integrated into the practice of neuropsychiatry.

Many diseases are much better understood as a result ofthe application of basic science. Idiopathic neuropsychiatric illnessessuch as schizophrenia have been the subject of intensive scientificscrutiny. Regional changes in brain structure have been identified andgenetic and environmental contributors to the syndrome discovered. Thepathophysiology of Alzheimer's disease has been revealed in substantialdetail including processing of the amyloid precursor protein to freeamyloid protein leading to neurotoxicity and the formation ofneuritic plaques. Abnormal accumulation of -synuclein is recognized as characteristic of Parkinson's disease and related conditions.This improved understanding of basic disease processes facilitatesidentification and interpretation of the clinical syndromes andprovides a basis for the development of therapeutic agents.

Marked progress has been made in pharmacotherapy.Neurology and neuropsychiatry have changed from clinical disciplineswith few available treatments to clinical arenas with majorneurotherapeutic options. Epilepsy, migraine, multiple sclerosis,Parkinson's disease, Alzheimer's disease, amyotrophic lateralsclerosis, psychosis, depression, obsessive-compulsive disorder,anxiety, sleep disorders, substance use disorders, and eating disordershave all been the subjects of development of new pharmacotherapeuticagents capable of
ameliorating disease-related symptoms and restoring more normal function.

The advances in all of these areas of neuroscience provide the basis for the update of neuropsychiatry developed in this volume.