Yes. Alcohol affects the cerebellum, which is a part of the lower brain that is responsible for controlling large movements. This is why you may lose your balance while you are drunk.
It all depends on the drug. Every drug affects your body differently. Certain drugs affect the nervous system, and some do not. From my understanding it all depends on how you take the drug too. For...
It affects your concentration, Shortens attention span Impairs judgment (if something is a good idea or not) Your reflexes are really slowed...which is another effect), Makes it harder to remember...