A social life and relationships change due to the use of these two things. The impact on the social life of a person various from individual to individual, and it also varies according to the amount of the same an individual uses.
Marijuana is a drug that will cause short-term problems with attention and memory. And thus you shouldn’t use it if you have an exam or something similar in near future. Marijuana also enhances some portions of the brain and person may experience a so-called “aha” moment. Some people consider those moments as evidence that cannabis use boosts memory, but the fact is that it stimulates creativity.
A person can become very creative under the influence of marijuana, but the subject they focus on might not be something productive. A person may suffer social alienation due to this creativity if the topic of that creativity fails to meet parameter of a social group they are in. It’s not strange to see a good relationship between a pothead (marijuana user) and a person that doesn’t use marijuana. But, in the majority of cases, a pothead will be in a company of those like him, because they can connect on a level and completely understand each other.
Alcohol affects social life on several levels, and we can talk about short-term effects and long-term effects. A drunken person can be funny and a good social figure, but they can also be aggressive and anti-social in situations that require some level of social interaction. Alcohol can cause embarrassing social slips due to lack of control a drunk has.
Both of these “substances” will change a person, and the change can be positive or negative. On the long term, the alcohol will change person totally, and sale can be said for cannabis as well. The changes aren’t same, but they still happen.