Plasma homovanillic acid and the dopamine transporter during cocaine withdrawal

Background: Plasma homovanillic acid (HVA) has been used as a measure of central dopaminergic activity but the validity of this method continues to be investigated. We used single photon emission tomography (SPECT) assessment of the dopamine (DA) transporter for comparison with plasma HVA in subjects at varying stages of abstinence from cocaine. Methods: Nineteen subjects were studied in two separate treatment sites. Plasma HVA and methoxyhydroxyphenethyleneglycol (MHPG) were measured by gas chromatography-mass spectroscopy (GC-MS). The DA transporter was quantified using the SPECT ligand [123I]BCIT. Results: At 2 weeks of abstinence and beyond there was an increasing positive correlation between plasma HVA and the SPECT measurement of the DA transporter (V3″). Conclusions: Plasma HVA may be more likely to reflect DA transporter density in the striatum when there is not a major drug-related change in the DA system.