Weed Make Teens Dumber? (2026 Study)

Added: 2026-05-21

[00:00:00]I started smoking weed when I was 15.

[00:00:03]Around the same time my grades dropped pretty significantly.

[00:00:07]I don't think it was the weed, but rather I stopped trying and started reading books on my own. The school material was always easy anyway.

[00:00:16]But there's a significant amount of research that seems to show that smoking weed as a teen slows cognitive development.

[00:00:23]A new study from University of California, San Diego found that teens who began using cannabis from ages 9 to 12 show slower age typical improvement in thinking and memory skills.