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Alcohol: Effects on Teenage Brains and Correlations Between Availability and Violence Darcy Cowan Jun 04

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ResearchBlogging.org

I’ve written previously about the effects of alcohol on decision making. Today I’ll be looking at two further aspects of alcohol consumption and how it affects society. First up is a study that examines the cognitive effects of moderate to heavy drinking during adolescence, with different effects on males versus females. Secondly I’d like to cover an interesting paper that relates the amount of violence in a community to the number alcohol outlets in the community.

There is an interesting contrast between the two papers, one focusing on the effects of alcohol on the individual and possible long term effects and the other on the wider community. Like tobacco the use of alcohol is coming under increased scrutiny in our society and this is a good thing. The difficult part in both processes is to ensure our actions are guided by evidence rather than knee jerk emotion. Smokers complain that they are unfairly victimised when alcohol causes so much harm, this may be true but it is irrelevant to the discussion of the harms of tobacco use. The same is true from the alcohol side of the debate.

Each substance must be approached and dealt with on it’s own merits and derailing the discussion to decry the abuse of one or the other is unhelpful. I am not an expert on public policy and do not advocate any particular solution to either of these issues, I don’t know what the best solution is but it is tiresome to see the same diversionary tactics arise time and again in these sorts of debates. With that, lets move on to the science.

The first paper, “Initiating moderate to heavy alcohol use predicts changes in neuropsychological functioning for adolescent girls and boys“, follows a cohort of 76 adolescents starting at ages 12-14 years. The participants of the study were chosen to limit the amount of exposure at baseline to addictive/mind altering substances. These individuals were then followed over approximately 3 years and given a battery of tests and questionnaires to determine their drinking habits and cognitive abilities.

As we might expect heavier drinking patterns in the adolescents predicted poorer test results. The interesting result is the differences in the effects of the alcohol in male versus female subjects.

Take the test Here

Female subjects that consumed higher amounts of alcohol in the preceding 12 months performed worse on tests of visuospatial functioning than the control group. One of the ways this was measured was using something called the Rey-Osterrieth Complex Figure test (see pic), this entails the subject copying the figure, and then drawing it again some interval of time later (in this case 30 mins) from memory.

The number of drinks required to see this effect appeared to be 12 or more a month (in the previous 3 months), with the larger doses leading to a more pronounced detriment. Of course this was a trend effect in a population, on average heavier drinking females did worse in these tests but any one female was not guaranteed to see a reduction in performance.

Males on the other hand tended to do worse in the attention tests. Going by this measure I’m sure wives the world over would swear their husbands had been habitual binge drinkers throughout adolescence. The test of sustained attention in this case was done by the Digit Vigilance Test, this simple test consists of rows of single digit numbers printed in either red or blue (single colour per page). Subjects must find either 6s or 9s on each page.

By timing the task and counting the errors committed a measure of sustained attention can be determined and compared to the control group.

A drawback of this work is that the number of subject was limited, the entire study had a total of 76 adolescents, of those 29 were female (leaving 47 males). These groups then had to be further bisected to give the drinking and control groups. This study was quite small but is consistent with previous research showing negative effect on the brain for developing individuals. The bottom line of research like this is not difficult to get to, there are detrimental effects to be had by allowing young people to indulging moderate to heavy alcohol consumption. What we do with this information is up to us.

The second paper was presented by William Pridemore and Tony Grubesic at the annual meeting of the American Association for the Advancement of Science in San Diego earlier this year. With the engaging title of “Alcohol outlets and community levels of interpersonal violence: Spatial density, type of outlet, and seriousness of assault” the paper examines the correlation between the number of places where alcohol is available in a community and the amount of violence the community experiences.

I think we can all guess the outcome but it’s nice to have actual data to back up our intuitions. The study was quite detailed in it’s approach with the violence broken down by simple assault and aggravated assault and the type of alcohol outlets subdivided into bars, restaurants and so-called “off-premise” outlets where alcohol is sold but not consumed on site, such as supermarkets and liquor stores.

It comes as no real surprise that a higher density of alcohol outlets was correlated with a higher level of violence in the area. A result that I did not expect though was the significant effect the “off=premise” alcohol outlets appear to have on the levels of violence in the area. The study estimated such sites contribute between 25%-30% of the violence (depending on the category)  of an area. This compares to approximately 10% each for bars and restaurants.

The reason for this difference is suggested to be that these areas can act as impromptu gathering places where it is perceived that the normal rules of society do not apply, especially if the area is unkempt in appearance. In such areas individuals may have an altered perception of the moral expectations and this coupled with the disinhibiting effects of alcohol could lead to the greater propensity for violence.

Once again the information may merely inform our decisions not make them for us. Is the best approach simply to limit the number of alcohol outlets, or ban then from some areas altogether (or completely?). Or should we use this information to put measures into place to reduce violence while retaining access to alcohol, perhaps by creating environments around outlets that are less conducive to violent confrontations. Maybe some nice waterfalls and soothing music would help, I’m sure I have an Enya CD around here somewhere I could donate to the cause (or possibly The Corrs).

Squeglia, L., Spadoni, A., Infante, M., Myers, M., & Tapert, S. (2009). Initiating moderate to heavy alcohol use predicts changes in neuropsychological functioning for adolescent girls and boys. Psychology of Addictive Behaviors, 23 (4), 715-722 DOI: 10.1037/a0016516

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Filed under: Psychological, Sciblogs, Science Tagged: Add new tag, adolescence, alcohol, alcohol consumption, Alcoholic beverage, American Association for the Advancement of Science: Caribbean Studies a Symposium, Binge drinking, health, Health and Medicine, neurological, psychology, Rey-Osterrieth Complex Figure, Science, Science and Society, violence

BioFuel Cell Batteries May Power Future Implanted Devices Darcy Cowan May 27

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ResearchBlogging.orgWhen I think about the future I sometimes indulge in fantasies that include “bionic” type implants. Not so much artificial muscles that will enhance strength (check this out) but devices that will expand our mental capabilities. Implants that give us greater memory, faster thought processes, the ability to download skills and knowledge directly into our brains.
Perhaps I read too much science fiction.

The trouble with this utopian view of the future is a practical one, where will these devices receive their power from? If I start forgetting things because I haven’t plugged in a new 9volt, I won’t be happy. The ideal solution would be some sort of battery that can be inserted into the body and generate energy from the food I eat, just like the rest of my organs.

Enter: The BioFuel cell. Fuel cells have been around for a few decades and while most people have no dealings with them their essential mechanism is easily understood. Basically a chemical reaction is allowed to proceed under very controlled conditions to generate a flow of electrons (ie an electric current). The usual example given is reacting Hydrogen (the fuel) with Oxygen to generate water and electricity, but really almost any electron donor/acceptor pair will do.

Biofuel cells replace the electron donor (eg Hydrogen as above) with a biological molecule, glucose. These Glucose BioFuel Cells (GBFCs) could then in theory utilise glucose dissolved the blood as a fuel to generate electricity and power implanted devices. The fanciful science fiction devices I dream about above may not arrive on the scene any time soon but there are medical devices and synthetic organs that would benefit from such a power source now.

The device that immediately springs to mind is a pacemaker but the possibilities are much wider, ranging from the artificial urinary sphincter that recipients of Radical Prostatectomy surgery depend on to artificial kidneys which to be portable must currently be wearable because of (among many other reasons) the inability to effectively supply it with power inside the body.

Existing GBFCs have a draw back that the electrodes are inhibited (work less efficiently) by chloride or urate ions, both of which are present in your blood, or require low (acidic) pH to work whereas your body likes to be around neutral pH. This makes them ineffective in a real biological environment. Luckily a recent paper in Plos ONE, “A Glucose BioFuel Cell Implanted in Rats“, details an alternative type of fuel cell that overcomes these limitations and demonstrates it by implanting it inside a rat.

The GBFC produced a specific power of 24.4 µW mL−1 which, to put that in perspective, could power two pacemakers (just in case The Doctor gets into trouble). The mL−1 part refers to the volume of the fuel cell, this really means that the power output is related to the size of the fuel cell, just like regular batteries. The volume of this cell appears to be little more than a quarter of a millilitre (0.266mL, two electrodes of 0.133mL each), think about how much volume a normal 6 sided die takes up, imagine one quarter of that and you’ll be in the right ball park.

Inside the fuel cell electrodes are enzymes that react the glucose with dissolved oxygen also in the blood to produce an electric current. The glucose and oxygen required for the reaction diffuse through a membrane surrounding the electrodes while the waste products diffuse back out into the bloodstream to be taken care of by the body. In this way the fuel is constantly being replenished and so long as the enzymes retain their activity the fuel cell will continue to function and continuously produce energy. The time scales measured in this study were only a few months but experiments by others suggests that the enzymes will stay active in a device such as this for at least a year and possibly more.

The authors of the study consider that a scaled up version of the device would be able to power medical implants with much greater power requirements than a pacemaker, such as the artificial sphincter mentioned above that they calculate would need almost 10 times the amount of power of a pacemaker. Seems like the limit at the moment is how much room you have to spare inside your body to house the fuel cell. Early pacemaker batteries took up about 90mLs worth of volume, that’s roughly a quarter the size of a drink can. It is mentioned that an animal such as a pig could accommodate a fuel cell 133mL in size but it is not made clear if this is an experiment that will actually occur. RoboPig.

All this is pretty exciting and with that sort of potential in a first generation fuel cell, I’m betting I can get my memory expansion before I start going senile. Now I just have to figure out what to do in the mean time.

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Cinquin P, Gondran C, Giroud F, Mazabrard S, Pellissier A, Boucher F, Alcaraz JP, Gorgy K, Lenouvel F, Mathé S, Porcu P, & Cosnier S (2010). A glucose biofuel cell implanted in rats. PloS one, 5 (5) PMID: 20454563

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Filed under: Medicine, Sciblogs, Science Tagged: Add new tag, Artificial pacemaker, Batteries, Biofuel cells, Devices, energy, Fuel cell, Health and Medicine, implantable devices, Medicine, pacemakers, Science