Drugs Synapse Activity Decreases. These brain scans highlight dopamine receptors, with areas of highest density shown in red. The meth abuser has severely reduced receptor levels. Other drugs, including alcohol, cocaine, and heroin, have the same effect. Aging An overwhelming number of studies have reported age-related changes in dopaminesynthesis, binding sites, and number of receptors.Continue reading “Toxic drugs , brain and Dopamine levels”