Neurobiology of cocaine-induced organic brain impairment: contributions from functional neuroimaging

The present review is directed at imparting the current knowledge regarding functional neuroimaging as a tool for enhancing the understanding of cerebrophysiologic and neurobehavioral consequences of stimulant abuse. Stimulants like cocaine are capable of inducing clinically significant neurocognitive impairment through direct action on the brain, and indirectly through other organs that influence cerebral physiology. Neurochemical dysregulation including profound effects on the serotonergic and dopaminergic systems have substantial physiological and neurobehavioral consequences. Brain hemorrhages, transient ischemic attacks, strokes,and seizures frequently follow cocaine use. The residual cerebropathologic consequences of cocaine are seen only in significant or pronounced brain events when structural neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are employed. However, recent research with newer functional neuroimaging techniques such as single photon emission, positron emission tomography, and quantitative electroencephalography have revealed high rates of significant alteration in brain function among cocaine users, with negative structural imaging studies. These findings are often associated with impairment on neuropsychological evaluation, also in the absence of positive findings on CT and MRI. Both cerebral metabolic and hypoperfusion anomalies are seen, especially in anterior and temporal brain regions. Observed changes can persist for months, and for some patients, may represent a permanent change in brain functioning.