may not recognize common dangers such as a hot stove; or may not realize that they need to use the bathroom and become incontinent. They may not want to get out of bed, or may need assistance doing so. Commonly, the person no longer recognizes familiar faces. They may have significant changes in sleeping habits or have trouble sleeping at all. Changes in eating frequently occur. Cognitive awareness is needed for eating and swallowing and progressive cognitive decline results in eating and swallowing difficulties. This can cause food to be refused, or choked on, and help with feeding will often be required. For ease of feeding, food may be liquidized into a thick purée. They may also struggle to walk, particularly among those with Alzheimer's disease. Subtypes Many of the subtypes of dementia are neurodegenerative, and protein misfolding is a cardinal feature of these. Alzheimer's disease Alzheimer's disease accounts for 60–70% of cases of dementia worldwide. The most common symptoms of Alzheimer's disease are short-term memory loss and word-finding difficulties. Trouble with visuospatial functioning (getting lost often), reasoning, judgment and insight fail. Insight refers to whether or not the person realizes they have memory problems. The part of the brain most affected by Alzheimer's is the hippocampus. Other parts that show atrophy (shrinking) include the temporal and parietal lobes. Although this pattern of brain shrinkage suggests Alzheimer's, it is variable and a brain scan is insufficient for a diagnosis. The relationship between general anesthesia and Alzheimer's in elderly people is unclear. Little is known about the events that occur during and that actually cause Alzheimer's disease. This is due to the fact that brain tissue from patients with the disease can only be studied after the person's death. However, it is known that one of the first aspects of the disease is a dysfunction in the gene that produces amyloid. Extracellular senile plaques (SPs), consisting of beta-amyloid (Aβ) peptides, and intracellular neurofibrillary tangles (NFTs) that are formed by hyperphosphorylated tau proteins, are two well-established pathological hallmarks of AD. Amyloid causes inflammation around the senile plaques of the brain, and too much build up of this inflammation leads to changes in the brain that cannot be controlled, leading to the symptoms of Alzheimer's. Vascular Vascular dementia accounts for at least 20% of dementia cases, making it the second most common type. It is caused by disease or injury affecting the blood