Relationship between toxicity of drugs and negative effects on brain?

Question

Are psychoactive drugs with lower lethal doses more neurotoxic (more damaging to the brain)? For example, tetrahydrocannabinol (one of the active components of cannabis) has a much higher lethal dose than benzoylmethylecgonine (cocaine), so could we deduce that cocaine is more damaging to the brain?Moreover, is a mathematical relationship between neurotoxicity and lethal doses known?

Answer 1

You can't directly relate lethality to effects on the central nervous system (CNS). In the given example, cocaine has effects not only on the CNS, but on many other organ systems as well, namely adverse cardiovascular effects. So, the answer to your initial question as to whether psychoactive drugs with higher lethality (lower lethal doses) are more toxic (more damaging to the brain), would be not necessarily. You can't make that generalization. As far as I am aware, there is no mathematical relationship between neurotoxicity and lethal doses. There are some drugs that are neurotoxic (kainic acid, ethanol, glutamic acid), but not all that lethal, and drugs that are quite lethal, but not neurotoxic.