|Nai Kiran Society is a not for profit voluntary organization, established in the year 2001 with an objective of providing barrier free rehabilitation services for people living with problem of drug addiction ,education & health care for marginalized sections of the society especially children ,women and senior citizen. Nai Kiran is a Hindi word means New Ray.|
Thursday, September 29, 2011
MRI scanners rely on extremely powerful magnetic fields. This is why you can't take metal objects into the scanner room, as they'd be pulled into it. Yet the fields can also exert other kinds of effects on the body.
I'd always been told that static, unchanging magnetic fields are biologically inert. But moving through the field too quickly can cause side effects. When an object moves through a magnetic field, induction happens - electrical currents are produced.
In the case of the human body, these small currents can activate nerve cells. Depending on which cells they hit this can cause you to feel dizzy, see flashes of light, experience tingling sensations, and so on. Or so I thought.
However, a new paper from Dale Roberts et al of Johns Hopkins shows that just being in a powerful magnetic field can cause dizziness and vertigo - with no movement required. They noticed that lying still in or near an MRI scanner causes nystagmus, abnormal horizontal eye movements, and that the amount of eye movement is directly correlated with the angle at which the head is positioned relative to the field.
The nystagmus was caused by an automatic reflex in response to effects in the vestibular ("balance") system of the ear. Roberts et al realized that the static magnetic field causes electrical currents that activate vestibular cells, even when the head is perfectly still. It happens because there's a natural flow of electrically charged ions into these cells in a part of the ear called the semicircular canal. The magnetic field interacts with this ion current, in what's called a Lorentz force.
The semicircular canals normally allow us to sense when our head is moving. Our eyes automatically compensate for head movement to keep us looking in the same direction. The MRI magnet fooled the ear into thinking the head was rotating, and the eyes produced nystagmus as a result.
Two patients who had suffered damage to their semicircular canals were immune to the effect.
This has important implications for functional MRI studies of brain function. Many people are interesting in measuring eye movements during MRI scans. This finding suggests that these movements may be unusual, compared to normal eye movements outside the scanner. Worst, the vestibular stimulation could alter brain activity:
Vestibular stimulation induced by the magnetic field in healthy subjects simply lying in the bore could activate many brain areas related to vision, eye movements, and the perception of the position and motion of the body.
Roberts, D., Marcelli, V., Gillen, J., Carey, J., Della Santina, C., & Zee, D. (2011). MRI Magnetic Field Stimulates Rotational Sensors of the Brain Current Biology DOI: 10.1016/j.cub.2011.08.029
Wednesday, September 28, 2011
The drug has to be completely out of the blood stream before the drug rehabilitation can continue; this effort can take up to a few days. There are some "flushes" offered over the Internet that allow the drug to be flushed out while the vitamins are absorbed. This can be done while taking the treatment but it can sometimes be not enough. There are some smaller chemical substances that the body stores while the addict uses. These substances are stored deep in the fatty tissue.
There may be detox tonics that you can drink to allow you to pass a drug screen but this does not get rid of the drugs that are in your body; these are merely a mask to help you pass the screening. The fatty deposits of the drugs often come to the surface when an addict is trying to quit and that is why addicts are usually unsuccessful. The deposits can cause cravings that can return for up to five years after the addict has already quit using.It is important to be able to get rid of as much of the drug as possible.
Narconon is a program that is used for detoxification and it has a very high success rate. The program allows for the detoxification of the body by ridding it of all of the toxins, even those that have been deposited into the fatty tissues. This form of drug detoxification can take up to 45 days to complete but the addict will exit feeling better than he has in years.
The use of a dry heat sauna helps the detoxification process and is normally used for 3 to 5 hours on a daily basis. This treatment plus all of the added vitamins and minerals will help any addict flush out his system even when it comes to the deeper deposits of drugs in the fatty tissues. Once the detox is completed, the addict will feel like a whole new person.
Effects of Drug Detoxification
The addict will all of a sudden have energy he had not possessed in a long time and his brain will begin to function properly. The former addict will be able to think more rationally and make clearer decisions. The drug cravings with this drug detoxification program are greatly reduced and there is a keener sense of smell, sight, and even taste. The once addict will all of a sudden feel a new sense of wellbeing and be able to take care of himself better. Things that may have been difficult to do in the past suddenly become simple and life gets a whole lot easier on the road to recovery.
Tuesday, September 27, 2011
People with schizophrenia are more likely to get better if they live in poor countries: that's been known for about 25 years. In the 1980s, a series of pioneering World Health Organization (WHO) studies looked at the prognosis for people diagnosed with schizophrenia around the world.
All of the data showed that people in developed countries were less likely to recover than those from poorer areas.
This paradoxical finding sparked no end of debate. What is it about these countries that makes them a better place to get schizophrenia? Patients in richer countries tend to have access to more and "better" psychiatric care, the latest drugs, and so on. Does this mean that those treatments are useless - worse, harmful? That's been the interpretation of some people.
But is it true? Not always, says a new study, W-SOHO. It's out in the British Journal of Psychiatry.
The authors compared schizophrenia outcomes in 37 countries. They recruited outpatients who were starting, or changing, antipsychotic medication. They found that in terms of "clinical" remission - i.e. improvement in the delusions, hallucinations, and other symptoms of schizophrenia - people in the developing world did indeed fare better than those from rich countries.
Over a 3 year period, 80-85% of patients from East Asia, the Middle East, and Latin America who started off ill, showed clinical remission, compared to 60-65% in Europe. That's not new: it confirms what the old WHO data showed.
But the new study also looked at "functional" remission - essentially, being able to participate in society:
having good social functioning for a period of 6 months. Good social functioning included those participants who had: (a) a positive occupational/vocational status, i.e. paid or unpaid full- or part-time employment, being an active student in university or housewife; (b) independent living; and (c) active social interactions, i.e. having more than one social contact during the past 4 weeks or having a spouse or partner.For functional remission, Northern Europe (e.g. the UK, France, Germany) was the best place to get sick, with 35% achieving it. Not a very high figure, but better than elsewhere: it was just 18% in the Middle East and 25% in East Asia, despite these areas having the highest chances of clinical remission. Latin America did pretty well, however, at 29%.
This is a very important finding if it's true. Is it solid?
First off, were Northern European patients just less ill to start with? Not really. They had the highest rates of suicide attempts. They tended to be older, and to have been diagnosed at a later age, which was correlated with worse functional remission. Regression analyses confirmed that region was a predictor of remission controlling for all the other variables.
However, Northern European patients did tend to have better function at baseline. They were more likely to be employed, living independently, and socially active when they entered the study. 63% were living independently which is much higher than anywhere else: it was 24% in Middle East and Latin America. 23% had a paid job compared to 17-19% in developing countries.
That's not a flaw in the study as such but it does suggest that the differences, whatever they are, are already in place before people get treated.
One concern I have is that the definition of "functional remission" may be North Europe-centric. "Living independently" is something we aspire to but in other places, with a strong tradition of the extended family household, the idea that it would be a bad thing for someone with schizophrenia to be living with their family might seem silly. If that means they'll be cared for and supported, what's wrong with it?
And in terms of paid employment, Northern Europe just has a stronger economy than most other places (erm... well, it did back in 2000 when these data were collected), so maybe it's no surprise that people with schizophrenia were more likely to have paid jobs.
In terms of the study itself, it was extremely large with over 17,000 patients enrolled. But here's the thing: this study was run by Lilly, the drug company who make olanzapine, an antipsychotic used in schizophrenia. Three of the authors on the paper are Lilly employees, and the lead author was a consultant for them. The study deliberately sampled lots of people taking olanzapine, presumably in order to find out whether they did better.
None of this necessarily means that the data aren't valid, but I'm just not sure I trust Lilly over the WHO.
Haro JM, Novick D, Bertsch J, Karagianis J, Dossenbach M, & Jones PB (2011). Cross-national clinical and functional remission rates: Worldwide Schizophrenia Outpatient Health Outcomes (W-SOHO) study. The British journal of psychiatry : the journal of mental science, 199, 194-201 PMID: 21881098
Saturday, September 24, 2011
It's pretty scary. A new epidemic disease comes out of nowhere and starts killing everyone. It infects the brain - victims suffer seizures, or fall into a coma, and die. It spreads like wildfire. Humanity's only hope lies in Lawrence Fishburne and Kate Winslet.
Luckily, that's fiction. But only just.
In the movie, the killer bug is called "MEV-1", but it might as well have been called the Nipah virus, because it was closely based on a real disease of the same name. So much so that this post about Nipah contains movie spoilers.
The Nipah Virus came to the world's attention in late 1998. There was an outbreak of a severe fever accompanied in many cases by encephalitis (viral infection of the brain) in Malaysia and Singapore. 276 patients were recorded. 40% of them died.
In the initial outbreak, there was probably no person-to-person transmission of the virus. Rather, only people who came into contact with Malaysian pigs - mainly farmers and butchers - caught the disease. Over a million pigs were culled in 1999 to try and contain the outbreak, and this seemed to be effective.
But since then, there have been several other smaller Nipah outbreaks in Asia, one almost every year in fact. In some of these, person to person transmission has been detected, notably in Bangladesh and India. The fatality rate in these more recent outbreaks has also been higher (70-90%). Luckily, unlike in the movie, it doesn't seem to be very contagious - so far. Most years have seen only 10 or 12 cases. But who knows what the future holds?
The virus is distantly related to measles, but is much more severe. Symptoms can begin anywhere from 4 days to 2 months after infection, but generally within 1 to 2 weeks. More recent outbreaks seem to have a shorter incubation period. The symptoms include fever, headache, vomiting, seizures, muscular jerks, and altered consciousness (confusion, coma).
Even after the initial infection is over, a minority of patients (4-8%) later suffer a relapse encephalitis. The virus seems able to remain dormant in the body before re-emerging to infect the brain again. Survivors may suffer neurological problems such as epilepsy, movement disorders, fatigue, and others. This is especially common following relapse encephalitis.
Where did it come from? It turns out that various strains of Nipah-like viruses are common in certain bats that inhabit various Asian countries, specifically fruit bats of the Pteropus genus, aka "flying foxes". The bats don't get sick, but infected bats are highly contagious, excreting the virus in their urine.
The virus seems to have made the leap into humans not once but several times, from different kinds of bats. Each outbreak could represent a new crossover event. Often there was an intermediate animal host, such as the domestic pigs in Malaysia .
Nipah is a classic zoonotic disease - it jumps from animals to humans. Zoonoses are scary for two reasons. They're new to humans, so humans haven't had a chance to develop immunity. And they may be especially deadly, because they haven't evolved not to be deadly to us.
Viruses and bacteria don't actually want to kill you. They want you alive, so that you can keeping breathing, walking, having sex, and otherwise spreading them. So pathogens tend to evolve to be less lethal to their primary hosts. Unfortunately, that's only good news if you are the primary host, and in the case of zoonoses, we're not. Bats don't get sick, but we do.
Lo, M., & Rota, P. (2008). The emergence of Nipah virus, a highly pathogenic paramyxovirus Journal of Clinical Virology, 43 (4), 396-400 DOI: 10.1016/j.jcv.2008.08.007
Friday, September 23, 2011
Thursday, September 22, 2011
So sang Jefferson Airplane in their psychedelic classic White Rabbit. While this song seems sure to have been inspired by the use of certain unapproved medications, don't have to be dropping acid to feel ten feet tall.One pill makes you larger
And one pill makes you small
And the ones that mother gives you
Don't do anything at all
Go ask Alice
When she's ten feet tall
A new paper from Germany reports on a case of "Alice In Wonderland Syndrome" associated with topiramate, an anti-epileptic drug also used to prevent migraines:
Alice In Wonderland Syndrome - the feeling that parts of the body have changed in size or shape - is a symptom known to be associated with various brain disorders, although it's not clear why it happens. It can occur in migraines. However in this case, the patient had never experienced such symptoms before she started on an anti-migraine drug.A 17-year-old girl presented with a 7-year history of migraine... she was put on 50 mg topiramate at night... after 4 months the dose was further increased to 75 mg/day, as she was still having three to four headache days/month.She then reported previously unknown intermittent nocturnal distortions of her body image only on those occasions when she did not directly fall asleep after taking topiramate. She described that either her head would grow bigger and the rest of the body would shrink, or that her hand resting comfortably on her chest would increase in size and become heavier, while the remaining arm would become smaller. The patient denied any hallucinatory character of these perceptions and insisted on their unpleasant but unreal nature...After reduction of topiramate to 50 mg/day, the nocturnal phenomena ceased within 2 weeks. The neurological and psychiatric examination was normal... We agreed with the patient to a rechallenge and increased the daily dose to 75 mg/day. Two weeks later the distortions reappeared again and the patient decided to discontinue the drug.
The authors conclude that while topiramate is an "excellent" drug, it can cause unusual side effects and they say that "The prescribing physician should be aware that it has the ability to induce various adverse effects and should encourage patients to report them - even if they initially appear awkward to them."
Jürgens TP, Ihle K, Stork JH, & May A (2011). "Alice in Wonderland syndrome" associated with topiramate for migraine prevention. Journal of neurology, neurosurgery, and psychiatry, 82 (2), 228-9 PMID: 20571045
Wednesday, September 21, 2011
Drug abuse blemishes the image of a prosperous society. Many capable youngsters are spoiling their lives by taking numerous harmful drugs. Is there a way to return to normalcy? Well! An alcohol & drug treatment can definitely improve the condition of a sufferer. By registering with alcohol rehab program, you can lead a peaceful, content and happy life. The success and improvement in life is entirely depends upon the selection of a drug treatment program. It is quite true that a wrong choice may not fulfill your purpose and your dream of improving your life will remain a dream only. So, why not to look for advanced alcohol addiction treatment programs to make the right choice.
One can find so many addiction treatment facilities in Los Angeles, California region to get the best possible treatment. The centers located in California region are known for their quality programs pertaining to all over improvement of a sufferer.In fact, distressed people get the chance to choose their own program at most alcohol and drug treatment centers. Some centers offer tailor-made therapies for sufferers who need extra care and guidance to overcome their habit of drug abuse.
Choosing the right alcohol rehab program is not a difficult task if adequate homework is done. As ignorance about the treatment centers may lead to wrong selection of treatment tactics and the atmosphere required to get over with the problem of drug abuse. While choosing the right kind of treatment center, you should check invariably peaceful environs. A center which is located at a peaceful environment significantly has a calming effect on the minds of drug patients. A proper and encouraging environment indicates better personal care and private living conditions to recover a lost addict. After all, the goal of an alcohol & drug treatment program is to cure the mind and the body as well.
Tuesday, September 20, 2011
Most of the studies on antidepressant use come from the USA and the UK, although the pattern also seems to hold for other European countries. The rapid rise of antidepressants from niche drugs to mega-sellers is perhaps the single biggest change in the way medicine treats mental illness since the invention of psychiatric drugs.
But while a rise in sales has been observed in many countries, that doesn't mean the same causes were at work in every case. For example, in the USA, there is good evidence that more people have started taking antidepressants over the past 15 years.
In the UK, however, it's a bit more tricky. Antidepressant prescriptions have certainly risen. However, a large 2009 study revealed that, between 1993 and 2005, there was not any significant rise in people starting on antidepressants for depression. Rather, the rise in prescriptions was caused by patients getting more prescriptions each. The same number of users were using more antidepressants.
Now a new paper has looked at antidepressant use over much the same period (1995-2007), but using a different set of data. Pauline Lockhart and Bruce Guthrie looked at pharmacy records of drugs actually dispensed, not just prescribed, and their data only covers a specific region, Tayside in Scotland. The 2009 study was nationwide.
So what happened?
The new paper confirmed the 2009 survey's finding of a strong increase in the number of antidepressant prescriptions per patient.
However, unlike the old study, this one found an increase in the number of people who used antidepressants each year. It went up from 8% of the population in 1995, to 13% in 2007 - an extremely high figure, higher even than the USA.
In other words, more people took them, and they took more of them on average - adding up to a threefold increase in antidepressants actually sold. The increase was seen across men and women of all ages and social classes.
There's no good evidence of an increase in mental illness in Britain in this period, by the way.
But why did the 2009 paper report no change in antidepressant users, while this one did? It could be that the increase was localized to the Tayside area. Another possibility is that there was an increase nationwide, but it wasn't about people with depression.
The 2009 study only looked at people with a diagnosis of depression. Yet modern antidepressants are widely used for other things as well - like anxiety, insomnia, pain, premature ejaculation. Maybe this non-depression-based use of antidepressants is what's on the rise.
Lockhart, P. and Guthrie, B. (2011). Trends in primary care antidepressant prescribing 1995–2007 British Journal of General Practice
Monday, September 19, 2011
Greece, of course, is rich in history (if not money, at the moment) and the National Archaeological Museum is predictably impressive. One of the most striking artefacts I remember was a kind of miniature suit made out of pure gold leaf, complete with a little face mask with tiny eye holes. It was the death mask of an infant from Mycenae, buried about 3000 years ago and dug up in the 19th century.
That's fascinating of course. When you think about it, it's also tragic. This was someone's baby son or daughter. However, it's hard to feel sad over it. If that baby died in front of you, or even if it happened yesterday and you read about it on the news, it would be sad.
You'd even feel sad if it were an entirely fictional baby that "died" in a movie. But being so old, it's not sad, it's just interesting, which is why these things have ended up in museums.
Most of the best exhibits are grave goods, placed in tombs with the dead, in the belief that the deceased would be able to use them in the next world. One Mycenaean warrior was buried with his sword, the blade specially bent so as to "kill" it, and ensure that it would travel to the afterlife with him.
That's fascinating, and also rather weird. Killing a sword so its dead owner could use the ghost of it in heaven? Those crazy ancients!
When you think about it, that's a horrible thing to think. That guy was probably a war hero and that grave was the most solemn memorial his culture could erect to his memory. That was the Arlington, the Tomb of the Unknown Soldier, of his day. We could have let it rest in peace. But we put it in a museum.
My point here is not that we ought to stop doing archaeology because it's offending the memory of the dead. What's interesting is the fact that no-one would even consider that. We just don't care about the dead of 3000 years ago, except as historical data. Yet there'd be outrage if someone went into a churchyard and starting digging up the dead of 300 years ago. You wouldn't even stuck some chewing gum to a gravestone or use it as a seat.
So there are two categories of the dead. There's the alive dead, who are felt to be with us, in the sense that they have a right to respect. Then there are the dead dead, the ancients, who are of purely historical interest. The alive dead still have power - wars are fought over their memories, honour, property rights.
Eventually, though, even the dead die, and that's generally a good thing. The Hungarians, so far as I know, don't dislike the Mongolians because of the Mongol Invasion of 1237, although the Hungarians who died then would probably have wanted them to.
Fortunately for modern international relations, they're dead.
Friday, September 16, 2011
Sunday, September 11, 2011
Stay away from addict friends
To stop your addiction to drugs or alcohol, you should stay away from anything that can bring you close to drugs and alcohol. One of the best ways to do it is to stay away from addict friends who help you in getting substance. Make efforts to be with friends who are sober and start hanging out with them. The more time you spend with sober friends, the less you will remember your addict friends and thereby stay away from addiction.
Do not remain idle
You have heard this proverb many times ‘An idle mind is a devil's workshop' and when it comes to drug or alcohol abuse, it sounds very true.When you have nothing to do and are bored, you may think of having drugs to get high. This temporary solution will definitely tempt you when you are alone doing nothing. The best way to overcome it is, taking up productive hobby. You can start watching movies or play computer games when you are alone. The bottom line is: do not remain idle.
What reasons you have for quitting your addiction?
If you do have a good reason for quitting your addiction, you will not be motivated to give up your habit. If you have no reasons for quitting, start researching about the consequences and ill-effects of the substance you are addicted to. Think about the reasons that made you take up addiction. Start thinking about how negatively drug addiction has influenced you life. In order to make sure there is no relapse, make sure you come up with strong reasons for quitting addiction.
Start building up your will power
To give up your habit, you need to have strong will power. Start reading books on how to build will power and self-control. Start doing activities that require determination, commitment and will power. This will keep you motivated and help you greatly in developing a mindset that your addiction to drugs can eliminated with a positive attitude towards life.
Stay away from substance abuse
Substance and abuse can be taken care of to a great extent by staying away from drugs or alcohol by any means. Think about it, if there is no source to get substance, you will not be able to have it and eventually let it go. It requires a strong will power. You can seek assistance from your friends and family members to make the substance inaccessible to you.
If nothing is helping you to get control over substance and abuse, you should get in touch with an addiction control rehab center. They will surely assist you in giving up your addiction and leading a normal life with complete abstinence from substance abuse.
Here's the problem. Suppose you want to know whether a certain 'treatment' has an affect on a certain variable. The treatment could be a drug, an environmental change, a genetic variant, whatever. The target population could be animals, humans, brain cells, or anything else.
So you give the treatment to some targets and give a control treatment to others. You measure the outcome variable. You use a t-test of significance to see whether the effect is large enough that it wouldn't have happened by chance. You find that it was significant.
That's fine. Then you try a different treatment, and it doesn't cause a significant effect against the control. Does that mean the first treatment was more powerful than the second?
No. It just doesn't. The only way to find that out would be to compare the two treatments directly - and that would be very easy to do, because you have all the data to hand. If you just compare the two treatments to control you might end up with this scenario:
An analogy: Passing a significance test is like winning a prize. You can only do it if you're much better than the average. But that doesn't mean you're much better than everyone who didn't win the prize, because some of them will have almost been good enough.
Usain Bolt is the fastest man in the world (when he's not false-starting himself out of races). Much faster than me. But he's not much faster than the second fastest man in the world.
Nieuwenhuis S, Forstmann BU, & Wagenmakers EJ (2011). Erroneous analyses of interactions in neuroscience: a problem of significance. Nature neuroscience, 14 (9), 1105-7 PMID: 21878926
Wednesday, September 7, 2011
Friday, September 2, 2011
What is drug addiction?
Thursday, 03 February 2011 19:35
Many people do not understand why individuals become addicted to drugs or how drugs change the brain to foster compulsive drug abuse. They mistakenly view drug abuse and addiction as strictly a social problem and may characterize those who take drugs as morally weak. One very common belief is that drug abusers should be able to just stop taking drugs if they are only willing to change their behavior. What people often underestimate is the complexity of drug addictionthat it is a disease that impacts the brain and because of that, stopping drug abuse is not simply a matter of willpower. Through scientific advances we now know much more about how exactly drugs work in the brain, and we also know that drug addiction can be successfully treated to help people stop abusing drugs and resume their productive lives.
Drug abuse and addiction are a major burden to society. Estimates of the total overall costs of substance abuse in the United Statesincluding health- and crime-related costs as well as losses in productivityexceed half a trillion dollars annually. This includes approximately 1 billion for illicit drugs,1 8 billion for tobacco,2 and 5 billion for alcohol.3 Staggering as these numbers are, however, they do not fully describe the breadth of deleterious public healthand safetyimplications, which include family disintegration, loss of employment, failure in school, domestic violence, child abuse, and other crimes.
What is drug addiction?
Addiction is a chronic, often relapsing brain disease that causes compulsive drug seeking and use despite harmful consequences to the individual who is addicted and to those around them. Drug addiction is a brain disease because the abuse of drugs leads to changes in the structure and function of the brain. Although it is true that for most people the initial decision to take drugs is voluntary, over time the changes in the brain caused by repeated drug abuse can affect a persons self control and ability to make sound decisions, and at the same time send intense impulses to take drugs.
It is because of these changes in the brain that it is so challenging for a person who is addicted to stop abusing drugs. Fortunately, there are treatments that help people to counteract addictions powerful disruptive effects and regain control. Research shows that combining addiction treatment medications, if available, with behavioral therapy is the best way to ensure success for most patients. Treatment approaches that are tailored to each patients drug abuse patterns and any co-occurring medical, psychiatric, and social problems can lead to sustained recovery and a life without drug abuse.
Similar to other chronic, relapsing diseases, such as diabetes, asthma, or heart disease, drug addiction can be managed successfully. And, as with other chronic diseases, it is not uncommon for a person to relapse and begin abusing drugs again. Relapse, however, does not signal failurerather, it indicates that treatment should be reinstated, adjusted, or that alternate treatment is needed to help the individual regain control and recover.
What happens to your brain when you take drugs?
Drugs are chemicals that tap into the brains communication system and disrupt the way nerve cells normally send, receive, and process information. There are at least two ways that drugs are able to do this: (1) by imitating the brains natural chemical messengers, and/or (2) by overstimulating the reward circuit of the brain.
Some drugs, such as marijuana and heroin, have a similar structure to chemical messengers, called neurotransmitters, which are naturally produced by the brain. Because of this similarity, these drugs are able to fool the brains receptors and activate nerve cells to send abnormal messages.
Other drugs, such as cocaine or methamphetamine, can cause the nerve cells to release abnormally large amounts of natural neurotransmitters, or prevent the normal recycling of these brain chemicals, which is needed to shut off the signal between neurons. This disruption produces a greatly amplified message that ultimately disrupts normal communication patterns.
Nearly all drugs, directly or indirectly, target the brains reward system by flooding the circuit with dopamine. Dopamine is a neurotransmitter present in regions of the brain that control movement, emotion, motivation, and feelings of pleasure. The overstimulation of this system, which normally responds to natural behaviors that are linked to survival (eating, spending time with loved ones, etc.), produces euphoric effects in response to the drugs. This reaction sets in motion a pattern that teaches people to repeat the behavior of abusing drugs.
As a person continues to abuse drugs, the brain adapts to the overwhelming surges in dopamine by producing less dopamine or by reducing the number of dopamine receptors in the reward circuit. As a result, dopamines impact on the reward circuit is lessened, reducing the abusers ability to enjoy the drugs and the things that previously brought pleasure. This decrease compels those addicted to drugs to keep abusing drugs in order to attempt to bring their dopamine function back to normal. And, they may now require larger amounts of the drug than they first did to achieve the dopamine highan effect known astolerance.
Long-term abuse causes changes in other brain chemical systems and circuits as well. Glutamate is a neurotransmitter that influences the reward circuit and the ability to learn. When the optimal concentration of glutamate is altered by drug abuse, the brain attempts to compensate, which can impair cognitive function. Drugs of abuse facilitate nonconscious (conditioned) learning, which leads the user to experience uncontrollable cravings when they see a place or person they associate with the drug experience, even when the drug itself is not available. Brain imaging studies of drug-addicted individuals show changes in areas of the brain that are critical to judgment, decisionmaking, learning and memory, and behavior control. Together, these changes can drive an abuser to seek out and take drugs compulsively despite adverse consequencesin other words, to become addicted to drugs.
Why do some people become addicted, while others do not?
No single factor can predict whether or not a person will become addicted to drugs. Risk for addiction is influenced by a persons biology, social environment, and age or stage of development. The more risk factors an individual has, the greater the chance that taking drugs can lead to addiction. For example:
Biology. The genes that people are born within combination with environmental influencesaccount for about half of their addiction vulnerability. Additionally, gender, ethnicity, and the presence of other mental disorders may influence risk for drug abuse and addiction.
Environment. A persons environment includes many different influencesfrom family and friends to socioeconomic status and quality of life in general. Factors such as peer pressure, physical and sexual abuse, stress, and parental involvement can greatly influence the course of drug abuse and addiction in a persons life.
Development. Genetic and environmental factors interact with critical developmental stages in a persons life to affect addiction vulnerability, and adolescents experience a double challenge. Although taking drugs at any age can lead to addiction, the earlier that drug use begins, the more likely it is to progress to more serious abuse. And because adolescents brains are still developing in the areas that govern decisionmaking, judgment, and self-control, they are especially prone to risk-taking behaviors, including trying drugs of abuse.
Thursday, September 1, 2011
While it's now (almost) generally accepted that men and women are at most only very slightly different in average IQ, there are still a couple of lines of evidence in favor of a gender difference.
First, there's the idea that men are more variable in their intelligence, so there are more very smart men, and also more very stupid ones. This averages out so the mean is the same.
Second, there's the theory that men are on average better at some things, notably "spatial" stuff involving the ability to mentally process shapes, patterns and images, while women are better at social, emotional and perhaps verbal tasks. Again, this averages out overall.
According to proponents, these differences explain why men continue to dominate the upper echelons of things like mathematics, physics, and chess. These all tap spatial processing and since men are more variable, there'll be more extremely high achievers - Nobel Prizes, grandmasters. (There are also presumably more men who are rubbish at these things, but we don't notice them.)
The male spatial advantage has been reported in many parts of the world, but is it "innate", something to do with the male brain? A new PNAS study says - probably not, it's to do with culture. But I'm not convinced.
The authors went to India and studied two tribes, the Khasi and the Karbi. Both live right next to other in the hills of Northeastern India and genetically, they're closely related. Culturally though, the Karbi are patrilineal - property and status is passed down from father to son, with women owning no land of their own. The Khasi are matrilineal, with men forbidden to own land. Moreover, Khasi women also get just as much education as the men, while Karbi ones get much less.
The authors took about 1200 people from 8 villages - 4 per culture - and got them to do a jigsaw puzzle. The quicker you do it, the better your spatial ability. Here were the results. I added the gender-stereotypical colours.
In the patrilineal group, women did substantially worse on average (remember that more time means worse). In the matrilineal society, they performed as well as men. Well, a tiny bit worse, but it wasn't significant. Differences in education explained some of the effect, but only a small part of it.
This was a large study, and the results are statistically very strong. However, there's a curious result that the authors don't discuss in the paper - the matrilineal group just did much better overall. Looking at the men, they were 10 seconds faster in the matrilineal culture. That's nearly as big as the gender difference in the patrilineal group (15 seconds)!
The individual variability was also much higher in the patrilineal society, for both genders.
Now, maybe, this is a real effect. Maybe being in a patrilineal society makes everyone less spatially aware, not just women; that seems a bit of a stretch, though.
There's also the problem that this study essentially only has two datapoints. One society is matrilineal and has low gender difference in visuospatial processing. One is patrilineal and has a high difference. But that's just not enough data to conclude that there's a correlation between the two things, let alone a causal relationship; you would need to study lots of societies to do that.
Personally, I have no idea what drives the difference, but this study is a reminder of how difficult the question is.
Hoffman M, Gneezy U, List JA (2011). Nurture affects gender differences in spatial abilities. Proceedings of the National Academy of Sciences of the United States of America PMID: 21876159