IMAGING STUDIES OF COCAINE USE DISORDERS
Brain Blood Flow Studies
Cerebral blood flow is a valuable indicator of brain function. Global and regional brain perfusion has been investigated in cocaine users at rest or during experimental cocaine administration, with and without the performance of mental tasks. These studies are briefly summarized below.
Transcranial Doppler (TCD) studies. TCD provides a noninvasive and economical imaging of blood flow in the CNS. Herning and coworkers used TCD to investigate 50 cocaine-using individuals and 25 control subjects. The participants were community-based volunteers who were studied within three days and again on day 28 of monitored abstinence. The study reported a statistically significant brain perfusion deficit in the anterior and middle circulations among the chronic cocaine users but not among the control subjects. Also, cocaine users showed an elevated cerebral vascular resistance as measured by the pulsatility index. The reported pul-satility index was comparable to those of elderly patients at risk for cerebrovascular events and remained unchanged at one month of monitored abstinence, indicating that the deficits were probably due to the chronic effects of cocaine. viagra oral jelly
Single photon emission computed tomography (SPECT) studies. The SPECT examination illustrates cerebral circulation using computer-generated images. The SPECT is a safe imaging technique that involves less expense and lower resolution than the positron emission tomographic (PET) scan.
Tumeh and colleagues conducted a rest SPECT study that revealed blood flow deficits in the frontal and temporal regions among 11 (seven were asymptomatic) out of 12 patients who had acknowledged using cocaine on daily basis. A SPECT study by Ernst and coworkers investigated 25 abstinent cocaine users and 15 control subjects. The cocaine users showed significant hypoperfusion in the putamen and temporal cortex as compared to control subjects. Interestingly, the SPECT scans by Levin and colleagues revealed fewer brain perfusion abnormalities in women than in men who used cocaine on long-term basis.
More recently, Gottschalk and colleagues used SPECT to compare the cerebral blood flow parameters of three study groups—namely, alcohol and cocaine patients (n=12), cocaine-only patients (n=20) and control subjects (n=20). Six participants had used cocaine four days prior to being scanned and the others were drug-free at the time of the study. Hyperperfusion was noted in the frontal cortex of 10 patients who had cocaine-use histories compared with 0 control subjects (p<0.005). The cocaine users also showed hypoperfusion in the temporal and parietal cortices. Concomitant cocaine and alcohol use appeared to worsen the hypoperfusion deficits among the cocaine users. Cialis Jelly
In their 1993 study, Strickland and coworkers combined SPECT with neuropsychologic examination of cocaine-using individuals who were abstinent for six months. In this cohort, the chronic cerebral blood flow changes correlated with decrements in neurocognitive functioning.
A study by Adinoff and colleagues evaluated 13 abstinent cocaine-dependent and 15 healthy comparison subjects. The cocaine group had completed 21-55 days of monitored abstinence prior to the study. The participants were scanned at rest and were then required to perform a gambling task that was designed to assess decision-making, which taps orbitofrontal cortex function. The observed scores in the gambling task did not differ significantly between cocaine-dependent patients and normal controls, although the performances showed a significant correlation with the blood flow in the anterior cingulate and the left dorsolateral prefrontal. The cocaine-dependent subjects had a lower left dorsolateral prefrontal cortex than the healthy comparison subjects.
Recently, Tucker and coworkers used a similar design to study 17 abstinent cocaine-dependent patients whose mean period of abstinence was 4.6 days. The study reported that perfusion within the anterior cingulate gyrus, middle frontal gyrus, medial frontal gyrus and superior frontal gyrus was negatively correlated with better performance in the Iowa Gambling Task. Tucker et al. noted that the cohort spent a great amount of time making card selection and suggested that the poor performance at the gambling task may be due to cognitive difficulties rather than impulsive response pattern. tricor medication
Magnetic resonance angiography (MRA). Kaufman and colleagues have used MRA to study blood flow in healthy male volunteers aged 29 years who were administered with either 0.4 mg/kg or 0.2 mg/kg of cocaine in a double-blind design. The study provided direct evidence that cocaine-induced cerebral vasoconstriction in a dose-related way and stratification of the subjects by prior cocaine use increased the strength of the association.