Teenage marijuana use: harmless?

Footnotes: if you see "(1)," or "(2)," and so on, refer to the bottom of the page for the source, which you can click on and read for yourself.
Marijuana is commonly used by my clients, and the most common reason they give is that it helps with their symptoms. Yet if this is true, why are they coming to see me, and why is their life still so hard? I could quote the 90's song, "If it makes you happy, it can't be that bad, but if it makes you happy, then why the hell are you so sad?" I'm not going to make a comprehensive argument here, but I hope this inspires you to look deeper into the most prominent, respected research, and to have the courage to challenge your views.
The latest generation, especially, is convinced that marijuana is harmless--60% of high schoolers believe this. Additionally, marijuana legalization has been shown to increase use among teens, especially because government approval reinforces the belief that marijuana is harmless, and even healthy (1). There are, in fact, medical studies that indicate that marijuana may have benefits for physical illnesses, for instance reducing nausea in chemotherapy patients (2). It is worth noting that sometimes (for instance with MS) these benefits are obtained simply through raw THC, and have nothing to do with getting high--the psychoactive effects of THC only occur when it is heated (5).
For most teenagers and adults, recreational marijuana use is anything but helpful. 48 separate studies show that marijuana is directly related to high school dropout. Research is conclusive that heavy users are at the greatest risk for unhappiness, poverty, criminality, and even an increased risk of suicide (3). And teens take note: a large study of adults who used marijuana regularly when younger reported that they wished they hadn't, because it led to negative life outcomes (3). What is the cause? Marijuana physically damages the developing brain, leading to difficulty concentrating and solving problems (1).
Those struggling with mental illness are especially affected. Some might say, "Well, depressed people who smoke weed are just searching for some peace, and marijuana isn't the cause of depression." But this is demonstrably wrong. A study following 1,600 14-15 year olds for seven years (that is, until they were in their early 20's), found that marijuana users were at significantly greater risk for becoming depressed--but just being depressed did not increase use (4). In other words, there is a provable, causal link between marijuana use and developing depression. Additionally, regular users with more severe mental illnesses increase double their risk of having a psychotic breakdown (4).
I may not convince many people here, but I'm not trying. I am simply encouraging marijuana users to actually read the research they don't like. Marijuana fans can quote their favorite studies against me. But one thing I notice: marijuana fans rarely take a serious look at the studies that show the risks of use. In behavioral psychology, this is called confirmation bias: if you believe it first, you go find studies to support it, and ignore the other side of the argument.
The emotional side of it for me, is that I spent four years of my early career working exclusively with adolescents and their families, and I cannot deny what I saw. I saw children with big dreams, big hopes, and a vision of a positive future. But when they started using marijuana, they stopped doing the things needed to achieve those dreams, such as valuing academic success. It was heartbreaking to see them "feel good" while their life was falling apart. And the end was often the same, the total breakdown and de-valuing of dreams altogether. Without a doubt, alcohol abuse has clear negative effects and a terrible personal and social cost. But the kids I've lost to marijuana, it's like watching a horrible train wreck in slow motion. I remember their faces when they were happy.
(1) Article in Psychology Today [click here]
(2) Article in ProCon.org [click here]
(3) Article from drugabuse.gov (an NIH site) [click here]
(4) Article from the UK Royal College of Psychiatrists [click here]
(5) Personal source. I had a friend with MS who drank a big, cold marijuana "smoothie" in the morning to prevent incontinence. This does not produce a high, and that's a good thing--the same amount of heat-activated THC would be deadly several times over.