Dopamine: Drill Sergeant or Lazy Bones?
Tuesday, 8th May 2012

How your brain processes dopamine may define whether you’re more prone to bust your can or sit back and slack. This, according to a new study from Harvard Medical School and Vanderbilt University published in a recent issue of the Journal of Neuroscience.

WebMD reports that study participants who had higher levels of dopamine in two areas of the brain known to play a role in how we process reward and motivation were busy bees. Those who were less willing to work hard had higher levels of dopamine in a different brain area which is involved in emotion and perception of risk.

Dopamine is a buzz word for people with Parkinson’s disease (PD), whose brains produce lower levels of the neurotransmitter. While this lack of dopamine itself is known to lead to PD motor symptoms such as rigidity and slowness of movement, it may also create biochemical reactions throughout the brain that can lead to non-motor symptoms such as apathy and depression.

Michael J. Fox Foundation staffer and movement disorders specialist Maurizio Facheris, MD, MSc explains that dopamine plays multiple roles in the complex network that is the human brain:

“Dopamine acts in four different areas of the brain, playing a unique role in human function in each of these areas, called pathways. Motivation is one of these roles (in the mesocortical pathway). Dopamine also controls movement (nigrostriatal pathway), tells us when we should feel good about something (mesolimbic pathway) and acts as a regulator of a hormone called prolactin in the pituitary gland (tuberoinfundibolar pathway).”

“The decreased levels of dopamine that occur in PD can also affect various areas of the brain not directly associated with these four dopaminergic areas, in effect, upsetting the chemical balance of the brain,” Facheris says. “When this happens, depression and cognitive impairment may occur.” (Last month, we shared results from a clinical study published in the journal Neurology confirming that two common drugs may ease depression in people with Parkinson’s without aggravating the motor symptoms of the disease).

On the other hand, too much dopamine in certain parts of the brain can lead to schizophrenia and compulsive disorders. This is important because certain PD medications that work to raise the level of dopamine in the brain can also sometimes induce compulsive disorders, hallucinations and mania.

“People should always feel confident to talk about their symptoms, whether it’s depression or compulsive disorders, with their movement disorders specialist,” says Facheris. “How you feel is a very personal experience, so treatment should also be personalized. Sometimes, small adjustments in treatment can easily reinstate that chemical balance and improve quality of life.”

Source:   The Michael J. Fox Foundation for Parkinson’s Research

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