For me, mental or physical stress increases my symptoms. I'm not sure if stress actually makes the symptoms increase or the medication less effective?
When I feeling the stress, I'll usually take an extra Sinemet if I feel like I'm off the bus sooner than expected and it helps me.

Stress will absolutely increase symptoms for someone with PD. Exercise and meditation are great to relieve stress. You may also want to talk to your Dr about your current dosing of carbidopa levodopa. My understanding is the med does not lose its effectiveness, but rather your situation may be progressing. When I start having trouble sleeping, slower to get going in the morning, decreased executive function (scatter brain or short term forgetfulness etc), and increased anxiety or depression it usually means it’s time for a tune up and I go see my neurologist or movement specialist. I also do my best to remove myself from stressful situations. Wish you the best!

I have had this problem for a couple of years now it's maddening! I lost an entire large suitcase after a trip! It's in my house and I can't find it. I have terrible short-term memory. I'm positive I'm going to have dementia. I write everything down all the time it's the only way I can get anything done. This is part of the process I guess. I'm sorry for you I hope yours doesn't get worse. 😔

Stress isn't good for Parkinson and I forgot the other question

I play "brain games" daily. Brain HQ was recommended during a Memory and Cognition study at UCSF's Brain and Aging center after a study was completed that I was accepted into. It has an annual subscription fee and is played on a PC. In lieu of that any strategy games on your phone can help and jigsaw puzzle are great for cognition!