your hypothesis is not the true answer- not a bad guess,
two shakey thumbs up!

I believe it is caused more by the environmental toxicity and the invasion of the mothers womb -
AND- vaccinations
AND
they have given bad drugs to women for years -
one is called - diethylstilbestrol = DES -which my mother took...
http://www.thefreelibrary.com/A+WOND.....-a0105758936
a multitude of toxins - like DDT, rotenone, monsanto-izum,
and...
mptp, - then there are tradegies of head injuries causing PD...
strokes can start the downward spiral of the brain degeneration,
as many people have a genetic marker - it does seem it is more prevalent
in families... however, I have experienced hypoglycemia/ and that was
my fork in the road to the beginning of brain damage...
all I can say is the brain needs to be fed, and evening primrose oil,
helps me, and co Q10 helps me -

this is the puzzle - and it hasnt been solved -thousands of pieces are missing
however -in my heart- the GDNF formula is the biggest key to healing
the brain... study what the GDNF is -
and take it from there...