Marijuana
THC, which is the active ingredient in marijuana, block receptors in the brain, many of which are responsible for memory. It also effects concentration and problem solving ability. It will also block pathways for sensory perception, increase the heartbeat and could bring on things like panic attacks.
Heroin
Brain cells can become dependent on this opiate, making it necessary to take to function normally. Opiates change the limbic system, which can make it difficult to feel pleasure, relaxation and contentment without the drug. Opiates can damage the brain stem which control automatic bodily functions such as breathing or coughing.
Cocaine
Cocaine blocks neurotransmitters in the brain, which stops the reabsorption of dopamine. Pleasure and euphoria comes from the build up of dopamine in the brain. After the cocaine has left the system, dopamine levels return to normal, but it leaves behind damaged receptors, making it harder to feel pleasure.
Ecstasy
It only takes one use of this drug to cause brain damage, it severs pathways within your brain. After time the brain can repair these pathways, but not as they once were. The pathway will be different which will effect certain processes. Memory has been showed to be impaired after use, it can effect the serotonin levels which cause depression.
LSD
LSD can cause many things, such as sleeplessness, trembling and raised heart rate. It can blur the lines between reality and what’s in their heads. The auditory and visual effects are cause by the brain being confused by a lot of information at once.
Methamphetamine
Methamphetamine use causes the brain to release dopamine to the synapse between nerve cells in the brain. This can result in euphoria, pleasure, brain swelling, brain hemorrhaging and paranoia. Methamphetamine use can lead to parkinson disease.