Neurology Now is a bi-monthly magazine in the USA for of the American Academy of Neurologists,. It is for neurologists, caregivers, and patients (patients get it free).
In the current print and online editions (Dec 2012-Jan 2013) there is an interesting sidebar in the article Not Just Tremor: Recognizing depression and other non-motor symptom.... (Page 23 in print edition) (As I have epilepsy, I qualify for a free subscription, oh boy. I'd rather trade the epilepsy and get a free subscription to Playboy, but I wasn't asked.)
While the article is mostly interesting to those with, or who give care to patients with Parkinson's, it discusses other problems which can show up as long as twenty years before the onset of tremors, including depression, sudden fatigue, social withdrawal, and irritability. The sidebar has the following interesting additional symptom that can come with those: the loss of religious belief.
"People with PD even have a tendency to lose their interest in religion—a change more readily considered philosophical than pathological. According to research by Patrick McNamara, Ph.D., of Boston University School of Medicine, people with PD report significantly lower levels of interest in religion. Brain scans show that this lack of interest coincides with changes in the prefrontal cortex but does not correlate with depression, age, education, intelligence, or medication."
The full article is at the Neurology Now link. Doctor McNamara has an interview in the Boston Globe at this link answering questions with a reporter about how he comes to this conclusion for the little-brained like me.
So, is your atheism a thing of reason and philosophical outlook, based on evidence (or its dearth in the case of religion), or the onset of Parkinson's? Dr. McNamara, a respected neurologist at Boston University School of Medicine, thinks in some cases it is a symptom of the latter.
It should be known that in the article he states he also studies the interface between science and religion, is not particularly religious himself, but has a lot of respect for religion and the vast array of religious expression around the world.
James, mostly snorting with disbelief over this ninny's interview. (On the other hand, he doesn't really want to lose his backers at the university and funding, so he has to be careful about what he says in public.)
That is another symptom of Parkinson's disease: gradual loss of intellectual level as measured by standardised IQ tests. While correlation is not causation, lower IQ and religiosity have also been shown as connected in a number of studies.
As far as exceptional intelligence (on either side of the distribution curve) it could either be a developmental anomaly, or continued proof of evolution by natural selection (as there is no demonstrable upper limit that causes an individual to be non-viable but there is a definite lower limit).
Were that to be the case with me (as epilepsy and Parkinson's are also related), before I take the long slide down the left side of the curve, shoot me and bury me with back issues of Playboy.
The doctor notes there is no correlation between intelligence and religion, but that has been repeatedly shown.