Following is a trick to remember the affects of drugs on humans:
Remember that all 3 drug mainly affect only 2 parts of your body.
|Central Nervous System (Brain)
How to remember the function of the following drugs:
|Body Part Affected
|Central nervous System - Decrease Activity
|Starts with letter 'O' which can be read as zero. So it makes your activity to zero. Which means it s a Depressant. Ironically an example name is just the opposite of zero i.e. Hero-ine .
|Both starts with letter 'Ca'. Remember since you remember this related with heard then other 2 drugs will fall in the category of Brain.
|Central nervous system - Increase Activity
|Coca can be related with Coke - Coke ads always come up during games like Cricket. So it can be related with increased level of activity.