Is there a connection between the time of the year and Parkinson's?

This can be broken down to:

Do PwP perform better relative to controls at some times of the year than others?

Is there a correlation between the date of birth and PD?

Knowing the answer to these questions would give a good clue as to the aetiology of PD. It would also have implications for dosing and for clinical trials.

Using imaging technology, a team based in Finland report a seasonal variation in PD.

People tested fall and winter compared to those tested in the spring and summer have "15% higher tracer uptake". Those born during winter and spring cf summer and fall have from 8% to 16% higher uptake capacity depending on site [1].

They conclude:

"The results suggest that there are seasonal oscillations also in the hypoactive dopaminergic system of Parkinson's disease patients. Findings concerning season of birth further suggest that there may be gestational or perinatal seasonal factors, which influence dopaminergic function in adulthood".

But, Canadian researchers using epidemiological data find [2]:
"no evidence of systematic seasonal variation in PD incidence by birth date, or of clustering of birth dates during influenza pandemic years in PD patients".

References:

[1] "Seasonality of striatal dopamine synthesis capacity in Parkinson's disease"
Valtteri Kaasinena, Pekka Jokinenb, Juho Joutsaa, Olli Eskolab, Juha O. Rinneb
Neuroscience Letters, Nov 2012
http://www.sciencedirect.com/science...04394012012931

[2] "Is there seasonal variation in risk of Parkinson's disease?"
Postuma R. et al.
MovementDisorders, May 2007
http://onlinelibrary.wiley.com/doi/1...21272/abstract

John