The relationship between fetal alcohol exposure and brain function is as complex as the brain itself. Recently, however, a study funded by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) may have found a common linkage--spontaneous activity of dopamine neurons--between prenatal alcohol exposure and attention-deficit/hyperactivity disorder (ADHD).
Although a mere three or four pounds in weight, the brain is composed of billions of nerve cells called neurons. Neurons communicate with each other at places called synapses by way of chemical messengers called neurotransmitters. Neurons generate electrical events called "action potentials" which cause neurotransmitters to travel across synapses, either "exciting" or "inhibiting" the "postsynaptic" or receiving cell. At any given moment, neurons are sending and/or receiving thousands of these messages. Scientists believe there are 100 or so different neurotransmitter varieties in the brain. Each neurotransmitter plays some role in most behaviors, but each neurotransmitter is often identified with a key behavior. Dopamine, for example, is strongly associated with motor system function, pleasure/reward, mental illness, craving and attention.
"The number of dopamine neurons isn't necessarily important," said Roh-Yu Shen, Senior Scientist at the Research Institute on Addictions, State University of New York and lead author of the study published in the November issue of Alcoholism: Clinical & Experimental Research. "What's important is how many of them are active."