RJ
Addiction's grip now seen as 'extreme memory'
By Carey Goldberg, Globe Staff | May 15, 2006
Explain this: An addict sweats through withdrawal. He commits to staying sober. With years of effort, he builds a life he loves. And then, one day, he passes his old shooting alley or gets pain pills from the dentist, and boom. Relapse. It all comes crashing down. By all accounts, something similar may have hit US Representative Patrick Kennedy earlier this month.
Old theories of addiction seem to fall short here. If the essence of addiction is dependence on a drug and fear of withdrawal symptoms, then why should this happen to a man who long since went through withdrawal? Or if addiction is about pleasure, why should a man embark on a course that will surely bring nothing but pain?
Last week, brain scientists gathered at the Massachusetts Institute of Technology batted around a newer theory that could fit a few more pieces into the puzzle and is already spurring experiments on new potential treatments.
The idea is that addiction may be a form of ''extreme memory" or ''pathological learning." And that addiction can be so potent and persistent because it takes over learning processes in the brain that are central to humans' very survival.
The brain evolved to identify essentials such as food or water and to record exactly how they can be reached, said Dr. Steven E. Hyman, a neuroscientist who is provost of Harvard University. And when it finds -- or even only expects to find -- such essentials, the chemical messenger dopamine is released. Its job in the brain is to say: ''This is very important; let's remember exactly how we did this."
Even though they provide no benefit to the body, drugs can usurp that system, he said, by releasing dopamine -- so much dopamine, in fact, that little else can compete, leading addicts' brains to ''overlearn" the false message that drugs are good.
Those surges of dopamine, the theory goes, contribute to the laying down of long-term memories and associations that remodel the connections in the brain and can last forever. MORE
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