Cognitive impairment in the elderly is often closely associated with diseases such as Alzheimer’s disease, cerebrovascular disease (cerebral infarction, cerebral haemorrhage), frontotemporal dementia and Parkinson’s disease. Cognitive impairment is also associated with brain ageing. As we age, reduced blood supply to the brain, decreased metabolism and reduced ability to clear toxins in the elderly can all cause brain nerve cell death, which can lead to reduced cognitive function.