A brain chemical linked to pleasure and depression may also trigger fear, according to a new study. Researchers say this may explain why the neurotransmitter dopamine, known to cause addictive behavior, may also play a role in anxiety disorders.

"Showing that dopamine can enhance both approach and avoidance behaviors is an important finding," says Howard Fields, a neurobiologist at the University of California, San Francisco. Approach behavior describes what someone attracted to an object does to obtain it. Fields says the finding reveals a new potential target for treating puzzling neurological disorders such as schizophrenia.

Scientists have long suspected that dopamine was linked to dread as well as delight. To confirm their suspicions, University of Michigan at Ann Arbor researchers studied what happens to rats when the neurotransmitter is blocked from reaching the rear portion of the nucleus accumbens, a brain region where dopamine is produced and reward-seeking activities (such as eating and other urges) as well as emotions including fear are processed.

Their findings, published in the Journal of Neurology: the animals remained calm even when scientists also removed a fear-controlling brain chemical (glutamate), which ordinarily would have sent them into a tizzy. This suggests that too much dopamine in the rear of the nucleus accumbens (linked to dread) may at least be partly responsible for the paranoia that many schizophrenia patients experience, study co-author Kent Berridge says.

"Some researchers have thought that dopamine may drive paranoia in schizophrenics," he adds. "The results are consistent with that idea."

7 Comments

1. 1. loosely_coupled 09:20 PM 7/14/08

   lol, I know it is very complex, but my god, now dopamine is related to anxiety? First it was lack of serotonin, then too much glutamate, now too much dopamine??

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2. 2. scottstafiej 12:02 AM 7/15/08

   Does dopamine's ability to affect avoidance AND approach behaviors have something to do with the area of the brain in which it's acting? Or is it moreso a dosage amount issue? What differentiates the response?

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3. 3. scottstafiej 12:04 AM 7/15/08

   Does the fact that dopamine affects approach and avoidance behavior have something to do with the brain region its acting in at the time, or is it more of a dosage issue? What differentiates the behavioral response?

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4. 4. frank011uba 07:14 AM 7/15/08

   How I wish that I would get a full and voluble edition of this publication. I have always been interested in having a great deal of knowledge in the study of human beings.

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5. 5. briskbot 11:21 AM 7/16/08

   http://www.lsa.umich.edu/psych/research&labs/berridge/publications/Faure,%20Reynolds,%20Richard%20&%20Berridge%20%20dopamine%20in%20desire%20&%20dread%20J%20Neurosci%202008.pdf
   
   The link to the paper taken from the co-authors website (http://www.lsa.umich.edu/psych/research&labs/berridge/Publications.htm)

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6. 6. briskbot 11:21 AM 7/16/08

   http://www.lsa.umich.edu/psych/research&labs/berridge/Publications.htm

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7. 7. clape 11:42 AM 1/2/10

   My mother has parkinson's disease and is showing all the symptoms related with the Dopamine. She lives in Colombia. How can I help her going through all this changes. Right now she doesen't want to eat.

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