Is a lack of facial expression when speaking a possible symptom of dementia?

Parkinson's ? Certain neurological diseases maybe associated with lack of facial expression or a "masked facies". Parkinson's disease or lewy body disease may present witih masked facies and be associated with dementia, but a lack of expression alone is not enough to make an association with dementia.
A lack of expression. Or masked facies, is frequently a symptom of parkinson's disease which involves dementia in 25-30 % of parkinson's patients.