transcript of episode 0: CANNABIS BURGERS FOR DEMENTIA, 1st January 2021

[🎶 INTRO: "Spring Swing" by Dee Yan-Kee 🎶]

welcome to the error bar: where neuroscience meets uncertainty

in this episode: why cannabis doesn't make you inject cocaine, how burgers don't give you dementia, & whether going into space expands your mind, or your brain

here is the brain news on the 1st January 2021:


CANNABIS IS A GATEWAY DRUG TO COCAINE (in adolescent male rats)

The Daily Mail this week screamed that cannabis really does lead users on to harder drugs like cocaine.

the reported study gave rats a synthetic cannabinoid drug twice a day for 11 days, with the dosage doubling every 4 days. a control group of rats instead had only a salt water drug under the same conditions.

one week after their last dose, all rats were injected with cocaine. the rats that had been on the cannabinoid drug were found to be more active – about 20-30 minutes after the cocaine, they walked around more than the control rats. this difference was about 10 extra metres walking over a 10 minute period – that's quite a lot for a rat.

in the rats' brains, lots of different chemicals were looked at, and some of those showed a strong statistical relationship between the brain areas examined and the drug combinations that the animals had received. the prefrontal cortex, which is an important part of the brain, was highlighted in particular.


is cannabis really a gateway drug to cocaine?

first, this is in rats. adolescent rats. adolescent, male rats. it didn't work in adult male rats, just 40 days older.

second, it's a single, synthetic cannabinoid drug, not cannabis. cannabis has several thousand different chemical constituents. this study tells us nothing about cannabis.

third, this was a one-way relationship – cocaine did not have the same effect on rats' responses to the cannabinoid. by The Daily Mail's logic, cocaine is therefore NOT a gateway drug to cannabis. so, is it OK for adolescent boys to inject cocaine? the error bar says no.

fourth, there is a LOT of detail in this paper – far too much to wade through, and way out of the error bar's expertise. it's not clear how much of these detailed results were theory-driven, and how much were post-hoc interpretations of a mass of data.

fifth, there is quite a strong whiff of cherry-picking of results. while the results in the main paper are rather strong, statistically speaking, several analyses in the appendices, which the main paper clearly relies upon, are much weaker. more problematically, several statistical interactions – a particular kind of statistical relationship – were reported as not significant in the results, but they were interpreted as if they were significant. misinterpreting statistical interactions is a common scientific error.


one synthetic cannabinoid drug affects young male rats' brains and behaviour in some ways, but adult male rats were not affected. how this relates to human drug use is unknown.


the science was by Scherma et al. 2020: Proceedings of the National Academy of Sciences of the United States of America; reported in The Daily Mail by @jwillchad on 20/Apr/20



The Express informs us that a diet rich in processed meat leads to dementia, and The Sun goes further, specifically blaming beef burgers and sausages, under the headline ALZHEIMBURGERS.

the story is based on a rather speculative paper by Samieri and colleagues in the journal Neurology. As part of a much larger longitudinal study in South West France, they analysed the food that 209 people, who later went on to develop dementia, reported eating in 2001-2002. these people were matched with 418 people who did not later develop dementia.

when originally given the food questionnaire, there were no statistical differences in ANY of the 62 kinds of food and drink between the two groups.

instead, what the paper suggested is that it is the specific combination of foods that is important for dementia. Not the overall amount or types of food eaten, but the combination.

there is a lot of complex data-mining in the paper, but essentially, people who reported eating French charcuterie, and who later went on to get dementia, also tended to report eating potatoes, soup, and yoghurt. yes, yoghurt.

by contrast, the control group who ate just as much charcuterie also tended to eat fresh vegetables and pizza. mmm, pizza.


do burgers and sausages cause dementia?

first, remember there were NO DIFFERENCES AT ALL in the amount of food eaten at baseline. even charcuterie was eaten IDENTICALLY in the two groups.

second, in one of the paper's graphs YOGHURT was showing just as strong relationships to dementia as charcuterie, so why isn't yoghurt making the headlines?

third, in the original questionnaire, no-one was ever asked about the specific combinations of foods that they ate, just how often they ate individual foods.

fourth, the group who went on to develop dementia, a) had significantly higher genetic risk of Alzheimer's, b) were significantly more likely to be diabetic, c) were significantly more likely to report having lost weight recently, and d) had a significantly lower mental state score at baseline.

overall, these are some very complex data-mining and statistical network analyses being used here to illustrate the story. they do not show that burgers cause dementia, just as they do not show that yoghurt or pizza do. or don't. it's very confusing.


this paper presents no evidence that burgers and sausages cause dementia.


the science was by Samieri et al. 2020: Neurology; reported in The Sun by @sturgios on 22/Apr/20, & The Daily Express by @KatrinaTurrill on 23/Apr/20

and the brain in brief...



The Daily Mail reports that wearing a glove can tap into your semi-conscious mind and improve your creativity.

the story is based on a Masters thesis by Adam Horowitz at MIT. The research has not been peer-reviewed or published.

in the main study, 2 groups of 25 participants were brought into the lab in the early afternoon. One group was kept awake, and the other induced to be sleepy. at multiple times they were prompted, sometimes given the word 'TREE'. later, they were asked to write a story.

the sleepy group spent longer writing their story, and that story was rated – by the experimenters who were not blinded to condition – as more creative. more objective linguistic analysis showed less clear and cohesive narratives in the sleepy group, taken as evidence of more creativity.


do data gloves boost creativity?

1. this should be peer-reviewed and published before it appears in a newspaper

2. there was a LOT of data analysis, but no mention of statistical corrections

3. assuming it's true, maybe there's a text-length effect that needs correcting?

4. assuming it's true, maybe sleepy people actually write longer, less coherent text?




the science was by Horowitz 2019 ; reported in The Daily Mail by @howardharry on 20/Apr/20



in case there was not sufficient uncertainty about the coronavirus pandemic, the Mirror and Express took up a story originally reported by Edinburgh Live.

that story reports on a Scottish woman who mentioned feeling a little bit strange on her Facebook account, after having contracted the virus. as if her brain was 'short-circuited'.


does coronavirus cause a freezing brain fog?

original source: One woman's report on Facebook, no controls. mentions isolation...

tabloids: 'reports of new symptoms are increasing' (they can't decrease). enough said.

i'm just going to park that story and move on.


ignore for now


reported in The Daily Express by Chanel Georgina on 17/Apr/20, & The Mirror by @MirrorMilo on 17/Apr/20



The Express reports a study from the journal Radiology, in which 11 astronauts' brains were measured before and after going into space.

Kramer and colleagues found that the astronauts' brains increased in volume by 27ml – a single measure of whisky (other spirits are available) - and that this increase remained for at least a year after space flight.

first: many congratulations for this work, it's obviously very difficult to study astronauts!


does space flight swell the brain?

1. there was no control group. None. So, it could be ageing, changes in the scanner...

2. the first scan was done, on average, 18 months preflight, while all the remaining scans were done between 3 days and 1 year after returning. space flight itself was an average of about 6 months. so, on average, there was 2 years between the first and second brain scans, but only one year between the 2nd and 6th.

3. ALL the differences are between post‐flight and pre‐flight. so, another way to frame this story is: Preparing for space flight expands your brain!

4. the error bars in figure 4 do not match the error bars in Table 2. tut tut.

5. the scientists themselves said that the changes were a bit like those when you lie down.




the science was by Kramer et al. 2020: Radiology; reported in The Daily Express by Sean Martin on 17/Apr/20



for some unknowable reason, this week, the Express reports two old studies examining links between vitamin D and depression.

they report a 2008 study on overweight and obese people, and a 2006 study on fibromyalgia – two completely different studies – in which both mentioned depression. in these studies, vitamin D supplements were said to reduce the symptoms of depression.


does vitamin d cure depression?

now clearly this is an important topic – but why drag up these old articles now? if they had looked a little harder, as the error bar has done, they could have found at least 6 systematic reviews and/or meta-analyses of the effects of vitamin D on depression published since 2013. three of these studies concluded there was no effect, and three that there was a benefit of vitamin D on depression.




the science was by Armstrong et al. 2007: Clinical Rheumatology, & Jorde et al. 2008: Journal of Internal Medicine; reported in The Daily Express by Jessica Knibbs on 22/Apr/20



if self-quarantine was not isolating enough, the Mail piles on the isolation by telling us that our shyness can be predicted by how we behaved as a 14‐month old.

the original study, by Tang and colleagues, in PNAS, reports on a herculean 3‐decade long study of infants, studied at 26 years old. in the study, the focus is mostly on some electrical brain data, but the headline focusses on the behavioural and personality data, so let's look at that.

the researchers took some questionnaire measures, combined them into a measure of 'reservedness', and also looked at other social and shyness measures. only one measure was strong enough not to be suspected as a 'false positive' - 14month olds who scored highly in 'behavioural inhibition' also scored highly in 'reservedness' 25 years later.


do shy children become shy adults?

1. as the authors acknowledge, the effects they report are quite weak – as might be expected for a 25-year-long correlation study!

2. the strongest statistical comparison is still relatively weak – the researchers could only account for about 13% of the differences between individuals based on their 14-month old inhibition scores

3. interesting, indeed. to their credit, the Mail did say 'tend to become' in their title.

but it seems their earlier title which remains at several places in the report: "Timid children become introverted adults with fewer friends" is not supported by the evidence!

i wonder who complained to them?


interesting, complex, but, yeah, ok


the science was by Tang et al. 2020: Proceedings of the National Academy of Sciences of the United States of America; reported in The Daily Mail by @jwillchad on 20/Apr/20

[🎶 OUTRO: "Cosmopolitan - Margarita - Bellini"by Dee Yan-Kee 🎶]

it's closing time at the error bar, but do drop in next time for more brain news, fact-checking & neuro-opinions. take care.

the error bar was devised & produced by Dr Nick Holmes from University of Birmingham's School of Sport, Exercise and Rehabilitation Sciences. the music by Dee Yan-Kee is available from the free music archive. find us at the error bar dot com, on twitter at bar error, or email talk at the error bar dot com