Pubdate: Tue, 09 Aug 2005
Source: Statesman, The (India)
Copyright: 2005 The Statesman
Contact:  http://www.thestatesman.net
Details: http://www.mapinc.org/media/3261
Bookmark: http://www.mapinc.org/topics/addiction (Addiction)

WIRED FOR ADDICTION

People Are Prone to Craving, the Propensity for Which Is an Ancient 
Strategy for Survival That Occasionally Goes Horribly Wrong. but It 
Also Turns Out That Our Addictive Instinct Has Helped Make US the 
Successful Species We Are Today

ADDICTIONS and cravings can come in all shapes and forms, but they 
all stem from a fancy piece of brain gear called the mesolimbic 
system. Scientists call this system the reward or reinforcement 
centre in the brain. It works like the brain's "High 5" -- when you 
do something positive, it says "Nice job!" And the way it does this 
is by releasing dopamine, a chemical that makes you feel good.

Who'd have thought that this group of 22 atoms -- eight carbon, 
eleven hydrogens, one nitrogen and two oxygens atoms (C8H11NO2) -- 
could play such a significant role in our lives? "The pleasure 
associated and the rewards from certain behaviours... all seem to 
involve dopamine," says Dr Andrew Moorhouse at The University of New 
South Wales.

Even something as straightforward as eating gives us a dopamine 
reward. When we eat, or have sex, the brain processes a positive 
stimuli and dopamine is released very deep in our brain, in the 
nucleus accumbens. The more dopamine released, the better we feel. 
You can get the same feeling by inserting an electrode into your 
nucleus accumbens and zapping it with a bit of electricity. 
Understandably though, most people just settle for a good meal.

When the brain rewards us in this way for certain behaviour, our 
impulse is to repeat it, reinforcing that it's good for us. Of 
course, nothing in the brain is quite so simple, but most scientists 
agree that things pan out that way.

But where did this system come from? Back when humans were far from 
the dominant species, if you didn't breed as effectively as possible, 
your genes simply didn't survive. Those who had a strong desire to 
have sex or find food were more successful in surviving and passing 
on their genes. That strong desire was driven by our ancestors' 
reinforcement system. The release of dopamine -- the High 5 chemical 
- -- encouraged them to undertake certain behaviours, like eating and 
reproducing. Because the individuals with the drive to eat and 
reproduce were the most likely to pass on their genes, the end result 
was that their food and sex seeking genes were passed on!

Even after a few hundred generations, we're still carrying around 
pretty much the same equipment upstairs. While we've evolved somewhat 
from our savannah dwelling forebears and can now perform all sorts of 
amazing feats like flying in the air and travelling into space, when 
it comes down to it, we still need to eat, drink and reproduce in 
order for our species to remain successful.

So the reinforcement system has stuck around, making sure that when 
we aren't keeping the boss happy or debating international politics, 
we're out looking for food and having sex. The problem is, because 
the dopamine system is so good at rewarding stimuli, and humans are 
good at solving problems, we've worked out ways to short circuit the 
system and get lots of dopamine in a hurry... by using drugs.

Scientists distinguish between natural rewards -- experiences we've 
evolved to find positive because they contribute to our wellbeing -- 
and artificial rewards like drugs and alcohol, which don't 
necessarily add to our wellbeing as organisms or as a species.

Natural rewards are there to make sure healthy living feels good, 
whereas artificial rewards are there to, well, just make us feel good 
no matter what.

Drugs key into that "High 5" area to such a degree that we get a 
bigger buzz than we're used to. Heroin and cocaine are the snipers of 
the neurochemical world, they're all about hitting the dopamine 
system and the poor old natural rewards like food just can't match 
them in terms of intensity.

This means that unfortunately for some people, drugs, especially 
heroin and cocaine, are very addictive. Where eating and drinking 
water only give us a tiny dopamine reward, taking drugs gives us a 
whole heap of the stuff. These substances are slotting exquisitely 
into an existing reward system.

Craving and addiction are two separate things. Craving turns into 
addiction when your motivation for an activity changes from receiving 
a reward to trying to prevent feeling the nasty effects of withdrawal.

David Kavanagh, a psychologist at the University of Queensland, 
describes this change as a switch from positive reinforcement to 
negative reinforcement. "Initially, the use of substances is actually 
quite pleasurable," he says. "If you become more highly dependent on 
the substance you tend to be using it more and more to alleviate 
withdrawal and alleviation of a negative state is negative reinforcement."

Dr Nicole Lee, a researcher from the Turning Point Drug and Alcohol 
Centre in Melbourne, who looks at alcohol and methamphetamine 
addiction, agrees. "You can be addicted to something and not crave 
it," she says. "Addiction can be a physical thing, where you are just 
taking the drug to stop your body from feeling bad."

Addiction certainly doesn't sound like a happy place to be, as anyone 
who is battling or recovering from an addiction will tell you. 
Kavanagh has been looking at what sets off a "Mmmm, I really feel 
like a... " craving. His research, done in conjunction with the 
University of Sheffield, found that just talking about something can 
trigger cravings in certain people!

Memory has a big part in making us crave, says Kavanagh, and a simple 
memory of a positive experience can be enough to make someone want to 
repeat it. However, memory is complex and we can get confused about 
positive and negative experiences, especially when we're tired or 
unhappy. "It's been found that people are much more likely to crave 
the use of substances when they're tired, when they're hungry, when 
they're in a negative mood. That is partly because they believe the 
substance will alleviate their despondency but it's also sometimes 
because they're not clearly introspecting about what the nature of 
their discomfort is," says Kavanagh.

People can believe they're craving one substance or activity, but are 
really confused and need something else. "It's a misunderstanding of 
what's going on internally with your motivation," he says. So when 
you think you need a coffee, you might actually need some sleep or 
food. Kavanagh says that if you're craving something, the worst thing 
you can do is try not to think about it. It might sound a little 
strange, but he says the best way to beat a craving is to not focus 
on it too much, but just let your attention wander over it and 
eventually it will move to something else.

But let's not beat up on dopamine too much. It's important to 
remember that the mechanism that leaves us susceptible to addiction 
- -- the mesolimbic system -- is also responsible for a lot of 
positives too. It makes eating chocolate feel good, it makes fresh 
fruit and vegies yummy and gives enough dopamine to make one feel not 
so close to death after a run.

All in all, it's a very well designed little system, but like 
anything, too much of a good thing can be bad -- even dopamine. 
People are pretty simple creatures really -- we just respond to a 
reward in the best way we know how. It's just a matter of choosing 
the natural rewards from the artificial ones. 
- ---
MAP posted-by: Richard Lake