The FIRSTS: The cause(s) of dinosaur extinction

A few days ago, a follower of mine gave me an interesting read from The Atlantic regarding the dinosaur extinction. Like many of my generation, I was taught in school that dinosaurs died because an asteroid hit the Earth. That led to a nuclear winter (or a few years of ‘nuclear winters’) which killed the photosynthetic organisms, and then the herbivores didn’t have anything to eat so they died and then the carnivores didn’t have anything to eat and so they died. Or, as my 4-year-old puts it, “[in a solemn voice] after the asteroid hit, big dusty clouds blocked the sun; [in an ominous voice] each day was colder than the previous one and so, without sunlight to keep them alive [sad face, head cocked sideways], the poor dinosaurs could no longer survive [hands spread sideways, hung head] “. Yes, I am a proud parent. Now I have to do a sit-down with the child and explain that… What, exactly?

Well, The Atlantic article showcases the struggles of a scientist – paleontologist and geologist Gerta Keller – who doesn’t believe the mainstream asteroid hypothesis; rather she thinks there is enough evidence to point out that extreme volcano eruptions, like really extreme, thousands of times more powerful than anything we know in the recorded history, put out so much poison (soot, dust, hydrofluoric acid, sulfur, carbon dioxide, mercury, lead, and so on) in the atmosphere that, combined with the consequent dramatic climate change, killed the dinosaurs. The volcanoes were located in India and they erupted for hundreds of thousands of years, but most violent eruptions, Keller thinks, were in the last 40,000 years before the extinction. This hypothesis is called the Deccan volcanism from the region in India where these nasty volcanoes are located, first proposed by Vogt (1972) and Courtillot et al. (1986).

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So which is true? Or, rather, because this is science we’re talking about, which hypothesis is more supported by the facts: the volcanism or the impact?

The impact hypothesis was put forward in 1980 when Walter Alvarez, a geologist, noticed a thin layer of clay in rocks that were about 65 million years old, which coincided with the time when the dinosaurs disappeared. This layer is on the KT boundary (sometimes called K-T, K-Pg, or KPB, looks like the biologists are not the only ones with acronym problems) and marks the boundary between the Cretaceous and Paleogenic geological periods (T is for Triassic, yeah, I know). Walter asked his father, the famous Nobel Prize physicist Louis Alvarez, to take a look at it and see what it is. Alvarez Sr. analyzed it and decided that the clay contains a lot of iridium, dozens of times more than expected. After gathering more samples from Europe and New Zealand, they published a paper (Alvarez et al., 1980) in which the scientists reasoned that because Earth’s iridium is deeply buried in its bowels and not in its crust, this iridium at the K-Pg boundary is of extraterrestrial origin, which could be brought here only by an asteroid/comet. This is also the paper in which it was put forth for the first time the conjecture that the asteroid impact killed the dinosaurs, based on the uncanny coincidence of timing.

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The discovery of the Chicxulub crater in Mexico followed a more sinuous path because the geophysicists who first discovered it in the ’70s were working for an oil company, looking for places to drill. Once the dinosaur-died-due-to-asteroid-impact hypothesis gained popularity outside academia, the geologists and the physicists put two-and-two together, acquired more data, and published a paper (Hildebrand et al., 1991) where the Chicxulub crater was for the first time linked with the dinosaur extinction. Although the crater was not radiologically dated yet, they had enough geophysical, stratigraphic, and petrologic evidence to believe it was as old as the iridium layer and the dinosaur die-out.

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But, devil is in the details, as they say. Keller published a paper in 2007 saying the Chicxulub event predates the extinction by some 300,000 years (Keller et al., 2007). She looked at geological samples from Texas and found the glass granule layer (indicator of the Chicxhulub impact) way below the K-Pg boundary. So what’s up with the iridium then? Keller (2014) believes that is not of extraterrestrial origin and it might well have been spewed up by a particularly nasty eruption or the sediments got shifted. Schulte et al. (2010), on the other hand, found high levels of iridium in 85 samples from all over the world in the KPG layer. Keller says that some other 260 samples don’t have iridium anomalies. As a response, Esmeray-Senlet et al. (2017) used some fancy Mass Spectrometry to show that the iridium profiles could have come only from Chicxulub, at least in North America. They argue that the variability in iridium profiles around the world is due to regional geochemical processes. And so on, and so on, the controversy continues.

Actual radioisotope dating was done a bit later in 2013: date of K-Pg is 66.043 ± 0.043 MA (millions of years ago), date of the Chicxulub crater is 66.038 ±.025/0.049 MA. Which means that the researchers “established synchrony between the Cretaceous-Paleogene boundary and associated mass extinctions with the Chicxulub bolide impact to within 32,000 years” (Renne et al., 2013), which is a blink of an eye in geological times.

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Now I want you to understand that often in science, though by far not always, matters are not so simple as she is wrong, he is right. In geology, what matters most is the sample. If the sample is corrupted, so will be your conclusions. Maybe Keller’s or Renne’s samples were affected by a myriad possible variables, some as simple as shifting the dirt from here to there by who knows what event. After all, it’s been 66 million years since. Also, methods used are just as important and dating something that happened so long ago is extremely difficult due to intrinsic physical methodological limitations. Keller (2014), for example, claims that Renne couldn’t have possibly gotten such an exact estimation because he used Argon isotopes when only U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) zircon geochronology could be so accurate. But yet again, it looks like he did use both, so… I dunno. As the over-used always-trite but nevertheless extremely important saying goes: more data is needed.

Even if the dating puts Chicxulub at the KPB, the volcanologists say that the asteroid, by itself, couldn’t have produced a mass extinction because there are other impacts of its size and they did not have such dire effects, but were barely noticeable at the biota scale. Besides, most of the other mass extinctions on the planet have been already associated with extreme volcanism (Archibald et al., 2010). On the other hand, the circumstances of this particular asteroid could have made it deadly: it landed in the hydrocarbon-rich areas that occupied only 13% of the Earth’s surface at the time which resulted in a lot of “stratospheric soot and sulfate aerosols and causing extreme global cooling and drought” (Kaiho & Oshima, 2017). Food for thought: this means that the chances of us, humans, to be here today are 13%!…

I hope that you do notice that these are very recent papers, so the issue is hotly debated as we speak.

It is possible, nay probable, that the Deccan volcanism, which was going on long before and after the extinction, was exacerbated by the impact. This is exactly what Renne’s team postulated in 2015 after dating the lava plains in the Deccan Traps: the eruptions intensified about 50,000 years before the KT boundary, from “high-frequency, low-volume eruptions to low-frequency, high-volume eruptions”, which is about when the asteroid hit. Also, the Deccan eruptions continued for about half a million years after KPB, “which is comparable with the time lag between the KPB and the initial stage of ecological recovery in marine ecosystems” (Renne et al., 2016, p. 78).

Since we cannot get much more accurate dating than we already have, perhaps the fossils can tell us whether the dinosaurs died abruptly or slowly. Because if they got extinct in a few years instead of over 50,000 years, that would point to a cataclysmic event. Yes, but which one, big asteroid or violent volcano? Aaaand, we’re back to square one.

Actually, the last papers on the matter points to two extinctions: the Deccan extinction and the Chicxulub extinction. Petersen et al., (2016) went all the way to Antarctica to find pristine samples. They noticed a sharp increase in global temperatures by about 7.8 ºC at the onset of Deccan volcanism. This climate change would surely lead to some extinctions, and this is exactly what they found: out of 24 species of marine animals investigated, 10 died-out at the onset of Deccan volcanism and the remaining 14 died-out when Chicxulub hit.

In conclusion, because this post is already verrrry long and is becoming a proper college review, to me, a not-a-geologist/paleontologist/physicist-but-still-a-scientist, things happened thusly: first Deccan traps erupted and that lead to a dramatic global warming coupled with spewing poison in the atmosphere. Which resulted in a massive die-out (about 200,000 years before the bolide impact, says a corroborating paper, Tobin, 2017). The surviving species (maybe half or more of the biota?) continued the best they could for the next few hundred thousand years in the hostile environment. Then the Chicxulub meteorite hit and the resulting megatsunami, the cloud of super-heated dust and soot, colossal wildfires and earthquakes, acid rain and climate cooling, not to mention the intensification of the Deccan traps eruptions, finished off the surviving species. It took Earth 300,000 to 500,000 years to recover its ecosystem. “This sequence of events may have combined into a ‘one-two punch’ that produced one of the largest mass extinctions in Earth history” (Petersen et al., 2016, p. 6).

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By Neuronicus, 25 August 2018

P. S. You, high school and college students who will use this for some class assignment or other, give credit thusly: Neuronicus (Aug. 26, 2018). The FIRSTS: The cause(s) of dinosaur extinction. Retrieved from on [date]. AND READ THE ORIGINAL PAPERS. Ask me for .pdfs if you don’t have access, although with sci-hub and all… not that I endorse any illegal and fraudulent use of the above mentioned server for the purpose of self-education and enlightenment in the quest for knowledge that all academics and scientists praise everywhere around the Globe!

EDIT March 29, 2019. Astounding one-of-a-kind discovery is being brought to print soon. It’s about a site in North Dakota that, reportedly, has preserved the day of the Chicxhulub impact in amazing detail, with tons of fossils of all kinds (flora, mammals, dinosaurs, fish) which seems to put the entire extinction of dinosaurs in one day, thus favoring the asteroid impact hypothesis. The data is not out yet. Can’t wait til it is! Actually, I’ll have to wait some more after it’s out for the experts to examine it and then I’ll find out. Until then, check the story of the discovery here and here.


1. Alvarez LW, Alvarez W, Asaro F, & Michel HV (6 Jun 1980). Extraterrestrial cause for the cretaceous-tertiary extinction. PMID: 17783054. DOI: 10.1126/science.208.4448.1095 Science, 208(4448):1095-1108. ABSTRACT | FULLTEXT PDF

2. Archibald JD, Clemens WA, Padian K, Rowe T, Macleod N, Barrett PM, Gale A, Holroyd P, Sues HD, Arens NC, Horner JR, Wilson GP, Goodwin MB, Brochu CA, Lofgren DL, Hurlbert SH, Hartman JH, Eberth DA, Wignall PB, Currie PJ, Weil A, Prasad GV, Dingus L, Courtillot V, Milner A, Milner A, Bajpai S, Ward DJ, Sahni A. (21 May 2010) Cretaceous extinctions: multiple causes. Science,328(5981):973; author reply 975-6. PMID: 20489004, DOI: 10.1126/science.328.5981.973-aScience. FULL REPLY

3. Courtillot V, Besse J, Vandamme D, Montigny R, Jaeger J-J, & Cappetta H (1986). Deccan flood basalts at the Cretaceous/Tertiary boundary? Earth and Planetary Science Letters, 80(3-4), 361–374. doi: 10.1016/0012-821x(86)90118-4. ABSTRACT

4. Esmeray-Senlet, S., Miller, K. G., Sherrell, R. M., Senlet, T., Vellekoop, J., & Brinkhuis, H. (2017). Iridium profiles and delivery across the Cretaceous/Paleogene boundary. Earth and Planetary Science Letters, 457, 117–126. doi:10.1016/j.epsl.2016.10.010. ABSTRACT

5. Hildebrand AR, Penfield GT, Kring DA, Pilkington M, Camargo AZ, Jacobsen SB, & Boynton WV (1 Sept. 1991). Chicxulub Crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico. Geology, 19 (9): 867-871. DOI:<0867:CCAPCT>2.3.CO;2. ABSTRACT

6. Kaiho K & Oshima N (9 Nov 2017). Site of asteroid impact changed the history of life on Earth: the low probability of mass extinction. Scientific Reports,7(1):14855. PMID: 29123110, PMCID: PMC5680197, DOI:10.1038/s41598-017-14199-x. . ARTICLE | FREE FULLTEXT PDF

7. Keller G, Adatte T, Berner Z, Harting M, Baum G, Prauss M, Tantawy A, Stueben D (30 Mar 2007). Chicxulub impact predates K–T boundary: New evidence from Brazos, Texas, Earth and Planetary Science Letters, 255(3–4): 339-356. DOI: 10.1016/j.epsl.2006.12.026. ABSTRACT

8. Keller, G. (2014). Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect? Geological Society of America Special Papers, 505:57–89. doi:10.1130/2014.2505(03) ABSTRACT

9. Petersen SV, Dutton A, & Lohmann KC. (5 Jul 2016). End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change. Nature Communications, 7:12079. doi: 10.1038/ncomms12079. PMID: 27377632, PMCID: PMC4935969, DOI: 10.1038/ncomms12079. ARTICLE | FREE FULLTEXT PDF 

10. Renne PR, Deino AL, Hilgen FJ, Kuiper KF, Mark DF, Mitchell WS 3rd, Morgan LE, Mundil R, & Smit J (8 Feb 2013). Time scales of critical events around the Cretaceous-Paleogene boundary. Science, 8;339(6120):684-687. doi: 10.1126/science.1230492. PMID: 23393261, DOI: 10.1126/science.1230492 ABSTRACT 

11. Renne PR, Sprain CJ, Richards MA, Self S, Vanderkluysen L, Pande K. (2 Oct 2015). State shift in Deccan volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact. Science, 350(6256):76-8. PMID: 26430116. DOI: 10.1126/science.aac7549 ABSTRACT

12. Schoene B, Samperton KM, Eddy MP, Keller G, Adatte T, Bowring SA, Khadri SFR, & Gertsch B (2014). U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction. Science, 347(6218), 182–184. doi:10.1126/science.aaa0118. ARTICLE

13. Schulte P, Alegret L, Arenillas I, Arz JA, Barton PJ, Bown PR, Bralower TJ, Christeson GL, Claeys P, Cockell CS, Collins GS, Deutsch A, Goldin TJ, Goto K, Grajales-Nishimura JM, Grieve RA, Gulick SP, Johnson KR, Kiessling W, Koeberl C, Kring DA, MacLeod KG, Matsui T, Melosh J, Montanari A, Morgan JV, Neal CR, Nichols DJ, Norris RD, Pierazzo E,Ravizza G, Rebolledo-Vieyra M, Reimold WU, Robin E, Salge T, Speijer RP, Sweet AR, Urrutia-Fucugauchi J, Vajda V, Whalen MT, Willumsen PS.(5 Mar 2010). The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary. Science, 327(5970):1214-8. PMID: 20203042, DOI: 10.1126/science.1177265. ABSTRACT

14. Tobin TS (24 Nov 2017). Recognition of a likely two phased extinction at the K-Pg boundary in Antarctica. Scientific Reports, 7(1):16317. PMID: 29176556, PMCID: PMC5701184, DOI: 10.1038/s41598-017-16515-x. ARTICLE | FREE FULLTEXT PDF 

15. Vogt, PR (8 Dec 1972). Evidence for Global Synchronism in Mantle Plume Convection and Possible Significance for Geology. Nature, 240(5380), 338–342. doi:10.1038/240338a0 ABSTRACT

The Benefits of Vacation

My prolonged Internet absence from the last month or so was due to a prolonged vacation. In Europe. Which I loved. Both the vacation and the Europe. Y’all, people, young and old, listen to me: do not neglect vacations for they strengthen the body, nourish the soul, and embolden the spirit.

More pragmatically, vacations lower the stress level. Yes, even the stressful vacations lower the stress level, because the acute stress effects of “My room is not ready yet”/”Jimmy puked in the car”/”Airline lost my luggage” are temporary and physiologically different from the chronic stress effects of “I’ll lose my job if I don’t meet these deadlines”/”I don’t know if I can keep my health insurance with this job”/”I’m worried for my child’s safety”/”My kids will suffer if I get a divorce”/”I can’t make the rent this month”.

Chronic stress results in a whole slew of real nasties, like cognitive, learning, and memory impairments, behavioral changes, issues with impulse control, immune system problems, weight gain, cardiovascular disease and so on and so on and so on. Even death. As I told my students countless of times, chronic stress to the body is as real and physical as a punch in the stomach but far more dangerous. So take a vacation as often as you can. Even a few days of total disconnect help tremendously.

There are literally thousands of peer-reviewed papers out there that describe the ways in which stress produces all those bad things, but not so many papers about the effects of vacations. I suspect this is due to the inherent difficulty in accounting for the countless environmental variables that can influence one’s vacation and its outcomes, whereas identifying and characterizing stressors is much easier. In other words, lack of experimental control leads to paucity of good data. Nevertheless, from this paucity, Chen & Petrick (2013) carefully selected 98 papers from both academic and nonacademic publications about the benefits of travel vacations.

These are my take-home bullet-points:

  • vacation effects last no more than a month
  • vacations reduce both the subjective perception of stress and the objective measurement of it (salivary cortisol)
  • people feel happier after taking a vacation
  • there are some people who do not relax in a vacation, presumably because they cannot ‘detach’ themselves from the stressors in their everyday life (long story here why some people can’t let go of problems)
  • vacations lower the occurrence of cardiovascular disease
  • vacations decrease work-related stress, work absenteeism, & work burnout
  • vacations increase job performance
  • the more you do on a vacation the better you feel, particularly if you’re older
  • you benefit more if you do new things or go to new places instead of just staying home
  • vacations increase overall life satisfaction

Happy vacationing!

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REFERENCE: Chen, C-C & Petrick, JF (Nov. 2013, Epub 17 Jul. 2013). Health and Wellness Benefits of Travel Experiences: A Literature Review, Journal of Travel Research, 52(6):709-719. doi: 10.1177/0047287513496477. ARTICLE | FULLTEXT PDF via ResearchGate.

By Neuronicus, 20 July 2018

The superiority illusion

Following up on my promise to cover a few papers about self-deception, the second in the series is about the superiority illusion, another cognitive bias (the first was about depressive realism).

Yamada et al. (2013) sought to uncover the origins of the ubiquitous belief that oneself is “superior to average people along various dimensions, such as intelligence, cognitive ability, and possession of desirable traits” (p. 4363). The sad statistical truth is that MOST people are average; that’s the whole definitions of ‘average’, really… But most people think they are superior to others, a.k.a. the ‘above-average effect’.

Twenty-four young males underwent resting-state fMRI and PET scanning. The first scanner is of the magnetic resonance type and tracks where you have most of the blood going in the brain at any particular moment. More blood flow to a region is interpreted as that region being active at that moment.

The word ‘functional’ means that the subject is performing a task while in the scanner and the resultant brain image is correspondent to what the brain is doing at that particular moment in time. On the other hand, ‘resting-state’ means that the individual did not do any task in the scanner, s/he just sat nice and still on the warm pads listening to the various clicks, clacks, bangs & beeps of the scanner. The subjects were instructed to rest with their eyes open. Good instruction, given than many subjects fall asleep in resting state MRI studies, even in the terrible racket that the coils make that sometimes can reach 125 Db. Let me explain: an MRI is a machine that generates a huge magnetic field (60,000 times stronger than Earth’s!) by shooting rapid pulses of electricity through a coiled wire, called gradient coil. These pulses of electricity or, in other words, the rapid on-off switchings of the electrical current make the gradient coil vibrate very loudly.

A PET scanner functions on a different principle. The subject receives a shot of a radioactive substance (called tracer) and the machine tracks its movement through the subject’s body. In this experiment’s case, the tracer was raclopride, a D2 dopamine receptor antagonist.

The behavioral data (meaning the answers to the questionnaires) showed that, curiously, the superiority illusion belief was not correlated with anxiety or self-esteem scores, but, not curiously, it was negatively correlated with helplessness, a measure of depression. Makes sense, especially from the view of depressive realism.

The imaging data suggests that dopamine binding to its striatal D2 receptors attenuate the functional connectivity between the left sensoriomotor striatum (SMST, a.k.a postcommissural putamen) and the dorsal anterior cingulate cortex (daCC). And this state of affairs gives rise to the superiority illusion (see Fig. 1).

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Fig. 1. The superiority illusion arises from the suppression of the dorsal anterior cingulate cortex (daCC) – putamen functional connection by the dopamine coming from the substantia nigra/ ventral tegmental area complex (SN/VTA) and binding to its D2 striatal receptors. Credits: brain diagram: Wikipedia, other brain structures and connections: Neuronicus, data: Yamada et al. (2013, doi: 10.1073/pnas.1221681110). Overall: Public Domain

This was a frustrating paper. I cannot tell if it has methodological issues or is just poorly written. For instance, I have to assume that the dACC they’re talking about is bilateral and not ipsilateral to their SMST, meaning left. As a non-native English speaker myself I guess I should cut the authors a break for consistently misspelling ‘commissure’ or for other grammatical errors for fear of being accused of hypocrisy, but here you have it: it bugged me. Besides, mine is a blog and theirs is a published peer-reviewed paper. (Full Disclosure: I do get editorial help from native English speakers when I publish for real and, except for a few personal style quirks, I fully incorporate their suggestions). So a little editorial help would have gotten a long way to make the reading more pleasant. What else? Ah, the results are not clearly explained anywhere, it looks like the authors rely on obviousness, a bad move if you want to be understood by people slightly outside your field. From the first figure it looks like only 22 subjects out of 24 showed superiority illusion but the authors included 24 in the imaging analyses, or so it seems. The subjects were 23.5 +/- 4.4 years, meaning that not all subjects had the frontal regions of the brain fully developed: there are clear anatomical and functional differences between a 19 year old and a 27 year old.

I’m not saying it is a bad paper because I have covered bad papers; I’m saying it was frustrating to read it and it took me a while to figure out some things. Honestly, I shouldn’t even have covered it, but I spent some precious time going through it and its supplementals, what with me not being an imaging dude, so I said the hell with it, I’ll finish it; so here you have it :).

By Neuronicus, 13 December 2017

REFERENCE: Yamada M, Uddin LQ, Takahashi H, Kimura Y, Takahata K, Kousa R, Ikoma Y, Eguchi Y, Takano H, Ito H, Higuchi M, Suhara T (12 Mar 2013). Superiority illusion arises from resting-state brain networks modulated by dopamine. Proceedings of the National Academy of Sciences of the United States of America, 110(11):4363-4367. doi: 10.1073/pnas.1221681110. ARTICLE | FREE FULLTEXT PDF 

The werewolf and his low fibroblast growth factor 13 levels

Petrus Gonsalvus, by anonymous
Petrus Gonsalvus, anonymous painting of the first recorded case of hypertrichosis in 1642. License: PD

Although they are very rare, werewolves do exist. And now the qualifier: werewolves as in people with excessive hair growth all over the body and not the more familiar kind that changes into a wolf every time there is a new moon. The condition is called hypertrichosis and its various forms have been associated with distinct genetic abnormalities.

In a previous report, DeStefano et al. (2013) identified the genetic locus of the X-linked congenital generalized hypertrichosis (CGH), which is a 19-Mb region on Xq24-27 that spans about 82 genes, resulting mainly from insertions from chromosomes 4 and 5. Now, they wanted to see what is the responsible mechanism for the disease. First, they looked at the hair follicles of a man afflicted with CGH that has hair almost all over his body and noticed some structural abnormalities. Then, they analyzed the expression of several genes from the affected region of the chromosome in this man and others with CGH and they observed that only the levels of the Fibroblast Growth Factor 13 (FGF13), a protein found in hair follicles, are much lower in CGH. Then they did some more experiments to establish the crucial role of FGF13 in regulating the follicle growth.

An interesting find of the study is that, at least in the case of hypertrichosis, is not the content of the genomic sequences that were added to chromosome X that matter, but their presence, affecting a gene that is located 1.2 Mb away from the insertion.

Reference: DeStefano GM, Fantauzzo KA, Petukhova L, Kurban M, Tadin-Strapps M, Levy B, Warburton D, Cirulli ET, Han Y, Sun X, Shen Y, Shirazi M, Jobanputra V, Cepeda-Valdes R, Cesar Salas-Alanis J, & Christiano AM ( 7 May 2013, Epub 19 Apr 2013). Position effect on FGF13 associated with X-linked congenital generalized hypertrichosis. Proceedings of the National Academy of Sciences of the U.S.A., 110(19):7790-5. doi: 10.1073/pnas.1216412110. Article | FREE FULLTEXT PDF

By Neuronicus, 17 November 2015

Cell phones give you hallucinations

A young businessman in a suit screaming at a cell phone. By: Benjamin Miller. License FSP Standard
Photo by Benjamin Miller. License: FSP Standard

Medical doctors (MD) are overworked, particularly when they are hatchlings (i.e. Medical School students) and fledglings (interns and residents). So overworked, that in many countries is routine to have 80-hour weeks and 30-hour shifts as residents and interns. This is a concern as it has been shown that sleep deprivation impairs learning (which is the whole point of residency) and increases the number of medical mistakes (the lack of which is the whole point of their profession).

Lin et al. (2013) show that it can do more than that. Couple internship and cell phones and you get… hallucinations. That’s right. The authors asked 73 medical interns to complete some tests before their internship, then every third, sixth, and twelfth months of their internship, and after the internship. The questionnaires were on anxiety, depression, personality, and cell phone habits and hallucinations. That is: the sensation that your cell phone is vibrating or ringing when, in fact, it is not (which fully corresponds to the definition of hallucination). And here is what they found:

 Before internship, 78% of MDs experienced phantom vibration and 27% experienced phantom ringing.
 During their 1-year internship, about 85 to 95% of MDs experienced phantom vibration and phantom ringing.
 After the internship when the MDs did no work for two weeks, 50% still had these hallucinations.

Composite figure from Lin et al. (2015) showing the interns' depression (above) and anxiety (below) scores before, during, and after internship. The differences are statistically significant.
Fig. 1. Composite figure from Lin et al. (2015) showing the interns’ depression (above) and anxiety (below) scores before, during, and after internship. The differences are statistically significant.

The MDs’ depression and anxiety were also elevated more during the internship than before or after (see Fig. 1), but there was no correlation between the hallucinations and the depression and anxiety scores.

These findings are disturbing on so many levels… Should we be worried that prolonged exposure to cell phones can produce hallucinations? Or that o good portion of the MDs have hallucinations before going to internship? Or that 90% the people in charge with your life or your child’s life are so overworked that are hallucinating on a regular basis? Fine, fine, believing that your phone is ringing or vibrating may not be such a big deal of a hallucination, compared with, let’s say, “the voices told me to give you a lethal dose of morphine”, but as a neuroscientist I beg the question: is there a common mechanism between these two types of hallucinations and, if so, what ELSE is the MD hallucinating about while reassuring you that your CAT scan is normal? Or, forget about the hallucinations, should we worry that your MD is probably more depressed and anxious than you? Or, the “good” news, that the medical interns provide “a model of stress-induced psychotic symptoms” better that previous models, as the authors put it (p. 5)? I really wish there was more research on positive things (… that was a pun; hallucinations are a positive schizophrenic symptom, look it up 🙂 ).

Reference: Lin YH, Lin SH, Li P, Huang WL, & Chen CY. (10 June 2013). Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes. PLoS One, 8(6): e65152. doi: 10.1371/journal.pone.0065152. Article | FREE PDF | First time the phenomenon was documented in press

By Neuronicus, 14 October 2015