There is evidence that cholesterol in the brain plays an important role in the neurotransmitter release. A decrease of the cholesterol level severely hampers the activity of the membrane fusion machinery, thereby inhibiting the release. Meanwhile, the results from several clinical studies suggest that a low cholesterol level is linked to the dysfunction of some brain activities. Because the neurotransmitter release underlies the basic brain function, the combined results lead to a testable hypothesis that the cholesterol-lowering drugs may inhibit the neurotransmitter release at the synapse. Such inhibition of the release could result in impaired brain function for a limited group of people. A molecular basis for the hypothesis is discussed.