Despite many similar behavioral and physiological effects, MA and cocaine differ significantly in their effects on the brain. MA creates stronger and longer lasting effects than cocaine [1,2], in part because cocaine is metabolized almost completely in the body whereas a large percentage of MA remains intact and active in the body longer. The slower metabolism of MA results in it being present in the brain longer than cocaine, leading to prolonged effects. Also, due to chronic levels of MA staying in the body longer, adverse effects such as psychosis are more commonly induced by MA than cocaine.
Although both cocaine and methamphetamine increase the levels of dopamine in the brain, animal studies have shown that the levels of dopamine are higher when MA is administered because of the drug’s effect on different mechanisms occurring within nerve cells.[1,5] For example, cocaine blocks dopamine re-uptake, prolonging dopamine activity in the brain, whereas MA not only blocks dopamine re-uptake, it also increases the release of dopamine. This in turn causes high dopamine concentrations in the synapse and thus longer lasting effects.
In general, MA causes three times more release of dopamine than cocaine and has a half life of 12 hours compared to cocaine’s one hour. If administered via smoking, MA produces a high for 8-24 hours, whereas cocaine produces a high for 20-30 minutes. See Table 1 for a summary of the differences between methamphetamine and cocaine.