--- title: Six Ways Science Says Marijuana May Hurt Your Health description: With the increasing push for the legalization of marijuana across the country, science is rolling out research on why pot may not be so harmless. canonical: https://time.com/2933349/marijuana-pot-danger-health-effects-science/ author: Becca Stanek article:opinion: false article:content_tier: free article:published_time: 2014-06-27T14:28:33.000Z article:modified_time: 2026-08-04T08:01:11.600Z article:section: Health og:title: Six Ways Science Says Marijuana May Hurt Your Health og:description: With the increasing push for the legalization of marijuana across the country, science is rolling out research on why pot may not be so harmless. og:url: https://time.com/2933349/marijuana-pot-danger-health-effects-science/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt5854996033ac4618/69868d8713c79f508b191e8c/ap112622977826.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 5184 og:image:height: 2916 og:image:alt: New Year Celebration og:type: article twitter:card: summary_large_image twitter:title: Six Ways Science Says Marijuana May Hurt Your Health twitter:description: With the increasing push for the legalization of marijuana across the country, science is rolling out research on why pot may not be so harmless. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt5854996033ac4618/69868d8713c79f508b191e8c/ap112622977826.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Six Ways Science Says Marijuana May Hurt Your Health > Sponsored content. 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Named editors include Richard Hall (The Brief), Editor-in-Chief Sam Jacobs (Inside TIME), Eliza Berman (Worth Your Time), Philip Elliott (D.C. Brief), Justin Worland (Future Proof) and Harry Booth (In the Loop). Health Matters is written by TIME's health desk. #### How do I sign up for a TIME newsletter? Go to time.com/newsletters, choose the newsletters you want and enter your email address. There is no cost and no subscription requirement. ## Video: Inside A Christian Pot Shop [Watch (HLS stream): Inside A Christian Pot Shop](https://cdn.jwplayer.com/manifests/vz4fpqkC.m3u8) (5:22)  _Published 2014-04-03. Bryan and Lanette Davies run a Christian medical marijuana dispensary in Sacramento. After God told Bryan to open a cannabis shop, the couple say they have been doing God's work in providing natural care to the sick._ by [Becca Stanek](https://time.com/author/becca-stanek/) ## Becca Stanek Jun 27, 2014 2:28 PM UTC  Partygoers smoke marijuana during a New Year's Eve party at a bar in Denver, celebrating the 2014 start of retail pot sales in Colorado. Partygoers smoke marijuana during a New Year's Eve party at a bar in Denver, celebrating the 2014 start of retail pot sales in Colorado. Brennan Linsley—AP by [Becca Stanek](https://time.com/author/becca-stanek/) ## Becca Stanek Jun 27, 2014 2:28 PM UTC Boosters of marijuana legalization [often speak about](http://norml.org/marijuana) the relative harmlessness of the drug, especially when compared to alcohol and tobacco, which [kill](http://ncadd.org/in-the-news/155-25-million-alcohol-related-deaths-worldwide-annually) [millions](http://www.cdc.gov/tobacco/data%5Fstatistics/fact%5Fsheets/fast%5Ffacts/) of people a year worldwide. But while the evidence suggests that pot is less damaging than some other legal drugs, the exact effects of marijuana on human health have not been well studied. Existing research is often limited in scope and rarely shows a clear causal connection. But there have been some worrying findings, especially considering the [increasing use](http://time.com/2929263/marijuana-pot-americans/) of marijuana by American adults. A paper published this year in Forensic Science International, for instance, described two rare deaths of young men that were attributed to heart conditions resulting from marijuana use. With legalization taking place in Colorado and Washington State, more research will now be possible. For now, here is a tour of what has been documented so far about marijuana’s negative effects. **1\. It can interfere with learning** Marijuana interferes with the brain’s cannabinoid receptors, affecting cognitive functions such as movement, memory, and emotional control. A recent small [study](http://www.nature.com/npp/journal/v25/n5/full/1395716a.html) found that impairment in working memory occurs immediately after marijuana use. Subjects who received a higher dose of THC—marijuana’s main active chemical—took significantly longer to complete immediate recall and mental calculation tasks. **2\. It can lead to dangerous driving** Pot impairs functions key to driving, including reaction time, hand-eye coordination and depth perception, a [study](http://gatton.uky.edu/faculty/sandford/391%5Ff13/marijuana.pdf) by the University of Chicago reported. In the first full year after medical marijuana was legalized in Colorado, there was a 12% increase in traffic fatalities, according to data analysis by researchers at Columbia University. However, studies have not been able to provide consistent evidence to prove that the effects of marijuana cause an increased rate of collisions. According to a different [study published in Accident Analysis and Prevention](http://www.sciencedirect.com/science/article/pii/S0001457512002412), the closest comparison to the culpability of accident when under the influence of marijuana is to a driver who has taken penicillin, anti-depressants or an antihistamine, which suggests marijuana’s effects have a nominal impact on accident risk. More research is needed. **3\. It may harm the developing brain.** Although a causal connection has yet to be found, [studies show regular marijuana use—once a week or more—can change the structure of the teenage brain](http://time.com/61940/recreational-pot-use-harmful-to-young-peoples-brains/). Marijuana affects memory and problem solving abilities, both of which can impact academic performance. Researchers from the [Harvard School of Medicine and Northwestern University Feinberg School of Medicine](http://jn.sfn.org/press/April-16-2014-Issue/zns01614005529.pdf) surveyed a small group between the ages of 18 and 25 and noticed structural abnormalities in the brain, specifically in grey matter, the nucleus accumbens, and the amygdala, after recreational marijuana use. **4\. It could make you panic.** Marijuana may alleviate anxiety for some, but for others it can cause it. THC can cause increased heart rate, poor coordination, or lightheadedness, which can be triggers for anxiety attacks. Some [research](http://www.ncbi.nlm.nih.gov/pubmed/17314727) suggests that people who frequently use of marijuana—and who started using it as young adults—were more likely to have anxiety disorders or depression. Whether cannabis use causes anxiety disorders, however, is not known. **5\. It can be addictive.** One in 10 users exhibits symptoms of dependence, according to the [American Psychological Association](http://www.apa.org/monitor/2010/06/marijuana.aspx). Marijuana’s rate of dependence liability of 9% is comparable to that of anti-anxiety medications and is well under the liability rates of alcohol (15%) and tobacco (32%), according to a [study by the Institute of Medicine](http://www.nap.edu/openbook.php?record%5Fid=6376). However, the reason why some become addicted and others don’t remains unclear. [Genetic studies](http://lib.gen.in/c987c901ebf0a6074145754113a4625b.pdf) have suggested that the involvement, or lack thereof, of CB1 receptors in response to cannabis can influence the likelihood of addiction. The receptor gene has been found to have a connection to the development of dependence to drugs and alcohol. Studies done on animals suggest that cannabis triggers reward centers in the brain, including neurons that produce dopamine, which could also encourage continued use. **6\. It can stress your heart** Marijuana-related deaths are so rare as to be treated as mythological by marijuana boosters, but a [paper published this spring in Forensic Science International](http://www.sciencedirect.com/science/article/pii/S0379073814000541) does describe the deaths of two healthy men, ages 23 and 28, who experienced heart trouble after using marijuana. “To our knowledge, these are the first cases of suspected fatal cannabis intoxications where full postmortem investigations, including autopsy, toxicological, histological, immunohistochemical and genetical examinations, were carried out,” the authors write. The authors surmise that the cardiovascular events were the result of increased heart rate that can happen in some pot smokers, particularly in the first hours after using marijuana. Nonetheless, the authors conclude, that the “absolute risk of cannabis-related cardiovascular effects can be considered to be low, as the baseline risk for most cannabis smokers is low and cannabis-induced changes are transient.” ## Transcript Good morning, Sacramento. This is Bryan Davies and Lanette Davies. [ INAUDIBLE ] I normally just pray, thank you lord, thank you lord, thank you lord. Thank you lord, for this chance. Thank you, lord, for everything. Thank you lord that it's a blessing that Lanette is. I have a fear of praying and asking for something. Since you're praying against his will, you're praying for evil. Well at this point in time I start praying, please help me, Lord. Help me, Lord. Tell me what to do. I need to get back in the business. I need to do something to be able to earn money. He said, open up a pot shop. And the Lord said, who are you not to do my will? [ MUSIC ] This has absolutely has been a ministry that has been ordained by God. So it is a christian dispensary, however, it is run by christians. Not all my employees are necessarily christian. It is not something that I require from them. Many people will stop because they are offended not by the marijuana but by the christianity. And it's a strangest thing. I was pissed that they open it up. It was not only embarrassing to me, it was this is, this is wrong, what are you doing? LIke I don't wanna be a part of it. When God told me to open up a cannabis shop, I go on the internet. [ SOUND ] They told us to target men between the ages of 20 and 30 years old because they'll spend the most on cannabis. We had a competitor, who used to have Bikini Wednesday. [ LAUGH ] Instead, I have a huge amount of elderly that are coming by and, you know, they've been taking handfuls, poundfuls of pharmaceuticals and getting sicker off of the pharmaceuticals! And they come over and say, do you have anything on this disease, or this disease. Or, are there any studies on this, and how do I get a cannabis recommendation? This has been, the whole time, has been an education process, so that people could take a look at a patient, and not see a stoner. Oh, you work there, that means that you get high all the time. It's like actually, no, we don't. We have people that come in here and they have cancer, and some of the people die. A lot of 'em were Christians and believers who were pissed at God. Yeah. So that's my whole Sunday Prayer started here. In the name of my lord, Jesus Christ, if any evil is in this room, may the lord rebuke it. I'm always watching the clock like, is it six o'clock yet? Cuz I'm eager to pray. And we pray for everyone. Even patients join in on our prayer. We wanna thank you for Lanette, Teva, Joe, Jeff, Ronnie [ CROSSTALK ] We've actually had employees that didn't want to participate for whatever reason [ UNKNOWN ], and it's okay. We're not here to judge you, one way or another. Hallowed be thy name, thy kingdom come. I've been coming here for four years, and I'm a very satisfied customer. [ INAUDIBLE ] You know what I'm saying, you cannot judge people for sinning differently than you. Amen. Amen. Thank you. [ CROSSTALK ] And that one lady, and what she said was, God's God and you know what, I've got cancer and I need all the prayers I can get. [ MUSIC ]. I think our court case is something that God has provided for us as an opportunity. We did keep completely clean records. Everything was absolutely done correctly, to the point that we did pass that audit with flying colors. Cana Care owes the IRS more than $ 800, 000 in income taxes. At issue is this 1982 law, that bans the deduction of expenses for trafficking and controlled substances. They allow you to take the cannabis as your deduction, but they disallow you all the legal expenses. So the IRS came back and said give us 194, 000 and they will drop everything, and I said no, I wanna go to court. But then they make this deal with you, if you give us a couple extra percent of gross sales, this all goes behind you. [ MUSIC ]. So is it illegal federally or is not illegal federally? Because you'll allow us to stay in business if we give you more money. [ MUSIC ] Crusaders For Patients Rights is my organization. It's kinda my, basis of what I do. Remove federal barriers for medical and scientific cannabis research, and create [ CROSSTALK ]. We have no problems putting together a protest. And we actually have done protests at the federal court building and we've done candlelight vigils. But even now, churches have even come on board. There are several of them that have actually said, you know, we don't have a problem with medicinal cannabis. They have none. As a matter of fact, they wanna have those options open. I use cannabis at night. I usually use a pipe, a small amount, and it usually is, you know, a couple of tokes and I go to bed. He has a pretty gnarly disease. He have [ UNKNOWN ]. I had never seen him sleep through a night until Cannabis. Until he used Cannabis. I had never seen him sleep through a night. And we were married 25 years. I go straight back to, you know, God created this as a man made herb. It is a medicine. And it works as a medicine. And when it comes down to it, God's commandment to us is to take care of the sick and ill. Let me ask you this, did God create pot? I know he did. [ CROSSTALK ] Created everything. And you know what I know about God? He is still working with you. I would not do, it if I didn't endorse what we were doing here. If I thought for one minute, that this was not the way that he wanted us to go. I would not be here. I'm always worried about being a negative reflection on christianity, because it's not what we wanna do, but at the same point, I would be negatively not following God's commandments. If I didn't take this stance and work it. And of course you know, weed was grown in the Garden of Eden, so you know, there's nothing but God around here. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/2933349/marijuana-pot-danger-health-effects-science/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/2933349/marijuana-pot-danger-health-effects-science/"},"headline":"Six Ways Science Says Marijuana May Hurt Your Health","datePublished":"2014-06-27T14:28:33.000Z","dateModified":"2026-08-04T08:01:11.600Z","description":"With the increasing push for the legalization of marijuana across the country, science is rolling out research on why pot may not be so harmless.","url":"https://time.com/2933349/marijuana-pot-danger-health-effects-science/","keywords":["Marijuana","Pot","Brain","Drugs","Anxiety","Science topic","Addiction","health","development"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt5854996033ac4618/69868d8713c79f508b191e8c/ap112622977826.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Becca Stanek","jobTitle":null,"url":"https://time.com/author/becca-stanek/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt5854996033ac4618/69868d8713c79f508b191e8c/ap112622977826.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"New Year Celebration","caption":"New Year Celebration","creditText":"Brennan Linsley—AP","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/marijuana/","name":"Marijuana"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/2933349/marijuana-pot-danger-health-effects-science/","name":"Six Ways Science Says Marijuana May Hurt Your Health"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"Inside A Christian Pot Shop","description":"Bryan and Lanette Davies run a Christian medical marijuana dispensary in Sacramento. 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