If You’re Still Smoking Weed at 30, Scientists Have Bad News
For many, smoking weed in their teens and early 20s is a rite of passage. College parties, lazy weekends, and experimental phases often come with a cloud of cannabis smoke. But if you’re still lighting up regularly into your 30s, science is sounding the alarm—and it’s not just about the munchies or couch-lock anymore.
Recent studies suggest that long-term marijuana use, especially when it extends into adulthood, may have more serious consequences than previously thought. One of the most comprehensive studies on the subject comes from New Zealand’s Dunedin Multidisciplinary Health and Development Study, which tracked over 1,000 individuals for several decades. Researchers found that persistent cannabis users who began in adolescence and continued into adulthood experienced a significant decline in IQ—up to 8 points by midlife.
That decline didn’t magically reverse even after users quit. The earlier and more regularly someone used cannabis, the more likely they were to show measurable cognitive impairments. Memory, attention span, and executive function all took a hit. In other words, if you’re still smoking weed regularly at 30, there’s a chance you’ve already lost a few steps mentally—and they might not come back.
But it’s not just brain function that’s affected. Mental health is another major area of concern. A 2022 study published in The Lancet Psychiatry found a strong link between regular cannabis use and increased risk of psychiatric disorders, especially in people with a family history of mental illness. Conditions like depression, anxiety, and even psychosis are more prevalent in regular users, particularly those who consume high-potency THC products.
There’s also growing evidence suggesting that cannabis use can affect motivation and emotional regulation. Chronic users often report feeling more apathetic, less interested in achieving long-term goals, and emotionally flat. This “amotivational syndrome” has been debated for years, but newer research using brain imaging has shown reduced activity in the brain’s reward centers in long-term users—especially those over 30.
And let’s not forget about the physical effects. While cannabis is often touted as being “safer than alcohol,” long-term smoking still harms the lungs. Chronic bronchitis, persistent cough, and other respiratory issues are common among daily users. Even vaping, often thought to be a healthier alternative, carries its own risks—especially due to the unknown long-term effects of inhaling vaporized chemicals.
To be clear, the occasional joint isn’t likely to derail your life. But for those who have made cannabis a consistent part of their lifestyle into their 30s and beyond, the science is raising some serious red flags. The adult brain is still susceptible to the effects of THC, and the damage can be subtle but cumulative.
So, if you’re still lighting up on the regular as you cross into your 30s, it might be time to take a step back and ask: Is this still serving me? Or is it quietly taking more than it gives?
