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