Brain blood flow is affected by bite for sure (see http:tmjcalifornia/elder-care-initiative). And brain blood flow can impact brain function in a wide range of ways. When a patient has a known condition associated with altered brain blood blow, the doctors never consider the bite as a possible cause. They should.
I came across an interesting example of how the bite impacts brain blood flow this week. When one eats something too cold- like ice cream, it causes a severe headache in the frontal area of the head (sometimes called a brain freeze). This pain is known to be preceded by a dramatic increase in blood flow to the pre-frontal cortex area of the brain (NPR story this week). What that means is that trigeminal nerve sensory is modulating pre-frontal blood flow. But the medical community does not know that bite misalignments can alter trigeminal sensory input, hence possibly causing dysfunction of the prefrontal cortex.
Many disorders, such as schizophrenia, bipolar disorder, and ADHD, have been related to dysfunction of the prefrontal cortex. Several studies have indicated that reduced volume and interconnections of the frontal lobes with other brain regions is observed in those with Attention Deficit Hyperactivity Disorder, schizophrenia, depression, and bipolar disorder; those subjected to repeated stressors; suicide victims;those incarcerated; criminals; sociopaths; those affected by lead poisoning;and drug addicts. It is believed that at least some of the human abilities to feel guilt or remorse, and to interpret reality, lie in the prefrontal cortex. The prefrontal cortex is presumed to act as a high-level gating or filtering mechanism that enhances goal-directed activations and inhibits irrelevant activations. This filtering mechanism enables executive control at various levels of processing, including selecting, maintaining, updating, and rerouting activations. It has also been used to explain emotional regulation.( http://en.wikipedia.org/wiki/Prefrontal_cortex).