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News, Research

Does Cannabis Affect Our Speech? A New Study Weighs In

Chane Leigh

by Chane Leigh

October 13, 2021 03:00 pm ET Estimated Read Time: 5 Minutes
Does Cannabis Affect Our Speech? A New Study Weighs In

Exploratory research recently published in the journal Drug and Alcohol Dependence found that cannabis consumption may be linked to subtle but long-lasting changes in speech. This associated impact on speech is said to be linked to effects on cannabis consumers’ motor functions, explained by Psychology Dictionary as activity or movement like walking and speaking that requires our brains and muscles to work together.

The team of researchers explains that slow, labored speech output as a result of cannabis use has long been suggested, but there is extremely limited evidence to support it. Fortunately, this 2021 study shed some light on the situation.

Speech Study Reveals Vague Findings

The aim of the study was to assess the speech within individuals who have a history of recreational cannabis consumption in comparison to the speech of non-consumers. The study collected samples from around 31 adults with a history of cannabis consumption and around 40 non-consuming adults. The participants were required to complete simple and complex speech-related tasks, which included a monologue, saying days of the week, and reading a phonetically balanced passage (known as “The Godfather Passage”).

The research team recorded participants’ tasks and then analyzed the audio using acoustic analysis. This allowed the team to get insight into measures of timing, vocal control, and quality. The team explained that there were subtle differences between the two groups of participants, particularly in timing, vocal effort, and voice quality, but that the data “remained equivocal,” meaning the differences were too small to deduce any sound conclusions.

Co-author of the study, Adam Vogel, posted on Twitter, “Speech is sensitive to brain health. Changes that occur from drug use can lead to changes in behaviors and cognitive/motor acts, even in otherwise healthy adults.” By comparing those with a history of cannabis consumption to those who don’t, the team of researchers was able to identify if cannabis actually has effects on speech. However, participants who had a history of other drug use like opioids were not included, as that could also impact the results.

Vogel explained that they “controlled for alcohol and cigarette smoking in cohorts,” so the differences they reported were “not the result of those two aspects of the speaker.” One of the most noticeable differences was when the participants read from “The Godfather Passage,” during which those with a history of cannabis consumption exhibited increased vocal effort and reduced vocal quality and intensity.

“There may be changes in neurological function resulting from prolonged use of cannabis and these may manifest in subtle alterations to speech,” Vogel said to PsyPost. “These changes are likely not detectable to the human ear, but require specialized methods for identification of the small but potentially genuine changes in performance.”

The researchers also found that the cannabis group was found to produce speech that had greater variability in pause length and were less likely to maintain consistent vocal intensity when compared to the control group (those with no cannabis consumption history). However, the differences they found were not statistically significant, meaning that it’s still not 100% certain that cannabis impacts these speech features.

Vogel also explained to PsyPost that the data from the study was limited to a single time point, as subjects were not followed over time. “We are making assumptions that the differences we observed between groups (cannabis vs. non-drug users) were the result of cannabis use and not something else we haven’t accounted for.”

So, What Does This Mean for Cannabis Consumers?

On its face, the study appears to support the potential for negative effects from regular cannabis use, but it ultimately needs more information to back any claims—a common trope when it comes to in-depth cannabis research. This means that cannabis consumers should be aware of a potential long-term impact on speech, but there is no guarantee this risk will be realized.

It’s also crucial to acknowledge that the potency of the cannabis consumed plays a role. For example, many have claimed (without concrete evidence) that slurred speech is a side effect of cannabis consumption. While the claim has not been comprehensively studied, slurred speech may actually be a result of consuming high-potency cannabis or high quantities that lead to intense highs. In fact, adverse side effects of cannabis are increasingly being linked to high potency.

A much older study, published in 1986, assessed the acute effects of cannabis on social conversation and also found that the speech quality of cannabis consumers significantly decreased. This study concluded by stating, “Marijuana appears to be an exception to the general rule that drugs of abuse increase verbal interaction.” However, this study has significant limitations since it was largely observational and conducted during a time when research on cannabis was tightly restricted.

Part of responsible cannabis consumption is proactively exploring the effects of the plant, both good and bad. Though research suggests there may be minor risks to be aware of as a regular cannabis consumer, the findings are not yet conclusive enough to cause alarm. One should also keep in mind the many proven medical benefits of cannabis that arguably outweigh the potential negatives.

Have you noticed any changes in your own speech since engaging in frequent cannabis consumption? Let us know in the comments below.

Post Your Comments

Elise says:

November 4, 2021 at 8:35 pm

I’ve been smoking roughly everyday for around 3 years now and during that time I’ve definitely noticed a difference. I’m not sure if it’s just one of those ‘brain fog’ moments where I’ve smoked too much the night before or maybe I’m even still a little high. But there’s consistently been times where I’ve noticed changes in my speech quality / execution. More noticeably with my ability to form sentences, as sometimes I have to think a bit harder or I might lose track of what I was saying, which kind of throws me off and sends me into a fluster. I’ve also found it more difficult at times to form sophisticated answers and I find myself feeling really dumb or having to really think about it. Even though before I started smoking heavily I was confident in executing speech without delays or fumbling but now I generally feel slower in high intensity settings.
That’s what caught my eye about this blog actually, as I’ve always thought long-term cannabis use may have some implications with our ability to execute speech with ease and comfortability. I’ve even seen it in one of my closest friends who started smoking large amounts roughly the same time as me and this also had an onset of a year or two. She too recognised this in herself. It is impossible to say if this is solely weed and not external influences impacting the brains ability to communicate sufficiently like stress, but is sure would explain a lot and it almost seems too coincidental to not mean anything. So thanks for sharing this post and hope you find this comment helpful / interesting 🙂

Chane Leigh says:

November 12, 2021 at 3:49 am

Hi Elise,
Thank you so much for taking the time to share your experience. It is definitely insightful as it helps us get ancedotal reports from seasoned cannabis consumers. I think there is some variance to be expected on effects of speech in terms of frequency of consumption as well as potency and quantity of consumption. I have also noticed differences in my speech but I like to tell myself that it is because I spend all of my English eloquence on articles and in my English classes (hehehe). Although, I must admit that the changes are not significant enough to cause any serious concern. I have also significantly reduced my consumption in order to reduce long term effects from cannabis consumption but in a way that I can still benefit from its therapeutic properties. Once again, thank you so much for sharing.

Jay says:

November 11, 2021 at 10:33 pm

I feel like it depends on your consumption, but sometimes I’ve noticed longer pauses between words/sentences, and sometimes slower than normal rate of speech. I believe I’m just taking more time to go over my thoughts…

I dig your articles : )

Shannon says:

January 14, 2023 at 11:24 pm

I’ve had a very interesting experience with my speech production in the last four years. I moved to a resort town after university and I started indulging in frequent cannabis use. I ended up hitting my head pretty hard on the mountain and didn’t realize the severity of the hit. I continued to ‘party’ and indulge in alcohol and marijuana use, and I started to notice subtle changes in my speech in the months following, beginning with starting to forget words I wanted to say or fumbling over words. A few months later, I visit home and stopped smoking weed for a week, and that’s where everything went awfully wrong. Gradually over the week, my speech got much worse to the point where I didn’t want to talk because I would stutter or forget my words or say the opposite word I was meaning to say or just felt a leg in my thoughts. I absolutely freaked out and thought there was something physically wrong with my head, so when I returned back to the resort town I got a CT scan done which showed no physical damage. I stopped drinking and smoking and tried to get to the bottom of my issue.. I went to the physiotherapist and they said I had post-concussion syndrome, linked to my head hit that spring (to put it into context, I hit my head bad in April and I was experiencing all these issues in November). I started going to a neurotherapist and doing biofeedback on my head. They determined that I had suppression primarily in my left frontal and temporal lobes, which does have an association with speech production, personality, memory, coordination, etc. At this point I essentially felt like I was living life like a zombie; I didn’t feel like myself at all, I talked very simply and avoided social contact altogether because I didn’t want people to see me like this. This was at the end of 2019, and the only true relief I have gotten since then has been smoking weed – for me it feels like my speech problems disappear when I am high as I can access my memories better and use more intricate words, and the speed at which I produce speech is faster. I feel like my brain operates a certain way when I am high, and when I don’t have thc running through my brain, my struggles return. I have had a few minor concussions in the last year, and have went through periods where I have stopped smoking completely for months, and although my neurotherapy work helps, I have not returned to regular speech function and have not felt like ‘myself’ since. A bit of a depressing story, but I beat myself up daily for doing this to my brain when it was still developing. I will continue to push forward, marijuana free, and hope that I can push my brain to develop new pathways to improve my speech and gaps in thinking, and potentially even work with a speech therapist because I can definitely tell my left side is weaker when producing speech and there may be more I can be doing. I also started seeing an osteopath so I am working on the structural issues from the concussions and healing my body. It’s crazy that people can smoke for several years and then stop and feel no different; for me it was a very different story. I always tell people that “there could be a whole study done on my brain.” Anyways, I’m not sure if anyone can relate to this or I can encourage people to ease up on the cannabis use, particularly after concussion. It’s important to let your brain heal without any negative influence. Thanks for the read.


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