[stana (OP)]

Ive heard that when i smoke marijuana   (which i DO NOT)
Chemicals from my brain are used and mixed with the compounds in the drug. Hence it damages my brain.

But a friend of mine, who used to drink heavily, says that he is more paranoid and depressed than a person who smokes marijauana?

Is this true?

[another_someone]

Tobacco is a drug for which we have a fairly good idea there is no safe level.

Cannabis was considered safe, but new evidence suggests it can cause paranoia, but I don't know that anybody has studied how common this is, and whether this is just under very heavy use, or only when used by people who have a predisposition to paranoia.

What does still seem certain is that cannabis is the least addictive of the 3 drugs.

Overuse of anything can be damaging, but the question always is to judge what amounts to overuse (and this can vary from person to person).  One cigarette, or one drink, will not kill you, but tobacco can be very addictive, so after taking a few, you may find it difficult to break the habit, and the habit will endanger your life.

The biggest problem with alcohol (and this is also true of cannabis, although with differences) is the short term impact if you consume too much (hospitals and police stations are full of people who have gotten drunk, and then either gotten violent, or been involved in an accident).  Most people suggest that cannabis, while likely to involve you in an accident, is less likely to lead to violence; but I don't know of any research to support this.

[paul.fr]

http://www.druginfo.adf.org.au/article.asp?ContentID=cannabis