Dementia is a broad category of brain diseases that cause a long term and often gradual decrease in the ability to think and remember such that a person's daily functioning is affected. Other common symptoms include emotional problems, problems with language, and a decrease in motivation. A person's consciousness is not affected. For the diagnosis to be present it must be a change from a person's usual mental functioning and a greater decline than one would expect due to aging. These diseases also have a significant effect on a person's caregivers. The most common type of dementia is Alzheimer's disease which makes up 50% to 70% of cases. Other common types include vascular dementia, Lewy body dementia, and frontotemporal dementia. Less common causes include normal pressure hydrocephalus, Parkinson disease, syphilis, and Creutzfeldt–Jakob disease among others. More than one type of dementia may exist in the same person. A small proportion of cases run in families. In the DSM-5, dementia was reclassified as a neurocognitive disorder, with various degrees of severity.