Being very anxious, stressed and depressed, worried can make your
memory poor - and also cause funny twitches (never mind making you
obsess about them and jump to scary conclusions) -  I suspect that may
be a more likely cause of your concerns. Have you talked to your
doctor about that aspect?

When I get really upset or worried, I often get a twitch in one eye
and eyebrow. Just the strangest thing, but definitely stress related
and not a sign of something dire.

Here are the symptoms of Parkinson's right from the best source - the
Parkinson's Disease Foundation http://www.pdf.org/AboutPD/symptoms.cfm

The best way to ward off future debility is to do what grandma and the
doctor always told you to do. Exercise, eat right, don't drink too
much, don't smoke, keep your weight down, keep your blood pressure and
cholesterol down, get lots of sleep, avoid stress, and keep your blood
sugar in line (a lot of people have Type 2 diabetes and don't keep a
good lid on it).

You can't control everything (like genetic, random chance and some
environmental factors) but you can take good care of yourself to up
the odds you'll last longer!

I'm a hobby genealogist, and for that reason, know a lot more about
what various relatives died from than most people (going back the 130
years or so you can get death records here with a cause of death on
them). Sometimes there are very sad exceptions, but most people who
died before their time died from accidents, infectious diseases, or
lifestyle or occupational diseases.

Certainly in the generation I've known in my family, a lot of people
have left us before they should of because of smoking, drinking,
overeating, and just totally neglecting blood pressure, cholesterol
and blood sugar, causing them to have all kinds of terrible
cardiovascular problems.
I know it doesn't do any good, but there are a few of them I'm still
kinda mad at (like the 67 year old family friend, mother of two and
grandmother of five who died this winter from...anorexia, if you can
believe it).
Given that we all live with the wolf at the door, better not to invite
him in by neglecting yourself or inflicting damage to yourself on
purpose.

Ask your doctor about your stress levels!!

M