The current demographic trend is dramatically changing; particularly the number of older
people is rising. This trend of older population causes an increase of aging diseases such as
dementia. At present the most frequent type of dementia is Alzheimer's disease, the second
most frequent type is vascular dementia, and the third one is dementia with Lewy bodies.
These are then followed by Parkinson's disease dementia, frontotemporal dementia/degen-
eration, and mixed dementia. The purpose of this review study is to explore speech and
language disorders of each of the above mentioned dementias and examine their similari-
ties and differences. Furthermore, the authors want to discuss the underlying factors
influencing language deterioration in dementia, suggest a few techniques which can assist
patients with dementia in communication and emphasize the role of preventive, noninvasive
strategies/therapies in this process.