Brain imaging studies of cocaine abuse: Implications for medication development

Contemporary in vivo brain imaging techniques confer the ability to assess brain function and structure noninvasively, and thereby can yield informati on to help guide the development of new treatments for substance abuse. The advantages and limitations of the major imaging modalities (positron emiss ion tomography [PET], single photon emission computed tomography [SPECT], s tructural and functional magnetic resonance imaging [MRI, fMRI, respectivel y]) are discussed with respect to their applicability to research on cocain e abuse. The effects of acute administration of cocaine have been studied u sing PET and fMRI, with PET manifesting decreases in cerebral glucose metab olism and blood flow, and fMRI revealing regional effects that are correlat ed temporally with subjective responses. In addition, studies of drug abuse rs, abstinent from cocaine for various lengths of time, have revealed persi stent differences in brain function and structure, especially in the fronta l cortex, when compared with parameters in the brains of subjects who do no t use illicit drugs of abuse. PET studies also have revealed abnormalities in markers for dopaminergic and opioid systems during withdrawal from cocai ne. Moreover, studies of cue-elicited craving for cocaine demonstrate a con nection between the response to drug related stimuli and neural elements of cognition and emotion. The future directions of in vivo brain imaging to i dentify functional and structural alterations in the brains of cocaine abus ers are discussed in relation to the development of medications to treat co caine dependence.