Communication involves a very complex web of abilities Abilities
Level at which certain actions and activities can be carried out.. If one segment of the web gets damaged, links between different areas of the web may not function properly. Mental associations, memories, recall and retrieval abilities are important components of the communication web and play a key role in language. One or more of these can be affected by Alzheimer's disease Alzheimer's disease
A neurological disease that affects memory and behaviour. It is characterized by beta-amyloid plaques and neurofibrillary tangles in the brain. There is no known cause but genetics and lifestyle are thought to play a role. and lead to difficulty with verbal expression. A person with Alzheimer's disease may be able to understand what other people are saying, and may be able to respond to it. However, they are slow in verbal expression due to trouble finding words, and they may repeat comments or phrases. Others may have difficulty with verbal expression because they cannot maintain a train of thought, or they may have problems stringing ideas together. They may complain of not being able to say what they mean and may rely on others to guess or finish their thought. At its extreme, Alzheimer's disease can cause a person to revert back to a first language which they rarely use in conversing.

Some types of dementia chiefly affect language. There are two types of frontotemporal dementia Frontotemporal dementia
A type of dementia that mainly affects the frontal lobe causing a problem in executive function tasks. which start with language problems. One is progressive Progression
A disease that is increasing in severity; going from bad to worse over time. nonfluent aphasia (also referred to as primary progressive aphasia). A second is known as semantic dementia. Language abnormalities can be tie first sign Sign
In medicine a sign is what a physician finds by examining a patient. For example, a patient with the symptom of pain might have signs of a fast heart rate, a pale face, a clammy touch and tenderness. in vascular Vascular
Relating to blood vessels that carry blood throughout the body. dementia, depending on where the initial stroke Stroke

Blood supply to the brain is interrupted, usually by a blood clot. As a result, a portion of the brain can die from not receiving enough blood and oxygen.