I cited in the book the circannual rhythm effect for PD sufferers - specifically that L-DOPA uptake slows down in the spring and summer.
Additionally, if you look at my "(Very) Simplified Timeline" graph on my November 5, 2014 blog post, you will note that I had a slight increase in required Levodopa dosage in the late spring and summer of both 2013 and 2014 (and a reduction again in about August).
I am asking "Why?" - and researching.
At minimum I have three initial thoughts. Perhaps three factors probably play a role:
1) Rapidly increasing day length (total heating and lighting) - as in the spring when the day length is rapidly increasing.
2) Longer day length - as in the spring and summer when the day lengths are overall longer than the fall and winter (even though slowly decreasing after the summer solstice, and slowly increasing after the winter solstice).
3) Perhaps dopamine is occupied or expended (consumed/destroyed) for body temperature regulation.
4) We know that dopamine is consumed to make melanin.
On factor 4, temperature regulation, so far I'm finding that dopamine activates body cooling. For example, the following paper supports that some dopamine agonists (substances that bind to the dopamine receptors, just like dopamine) have been shown to go so far as to induce hypothermia in primates:
http://www.sciencedirect.com/science/article/pii/S0361923080800037
So this confirms 3), supports the circannual effects observed, and gives us a clue to factors 1) and 2).
Certainly we know then that dopamine supply in the spring and summer is diminished by preoccupation with cooling, and consumption for pigmentation.
I am looking in to this. It may be useful for understanding the right season sleep-wake patterns to optimize PD management, the optimal exercise practices, possibly the application of light therapy to mitigate the rate-of-change effects, and maybe even the timing of eating cycles.
More soon,
God Bless,
Glen Pettibone
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