Dementia is a broad category of brain diseases that cause a long term and often gradual decrease in the ability to think and remember that is great enough to affect a person’s daily functioning. Other common symptoms include emotional problems, problems with language, and a decrease in motivation. A person’s consciousness is usually not affected. A dementia diagnosis requires 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 (25%), Lewy body dementia (15%), and frontotemporal dementia. Less common causes include normal pressure hydrocephalus, Parkinson’s 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. Diagnosis is usually based on history of the illness and cognitive testingwith medical imaging and blood work used to rule out other possible causes. The mini mental state examination is one commonly used cognitive test. Efforts to prevent dementia include trying to decrease risk factors such as high blood pressure, smoking, diabetes, and obesity. Screening the general population for the disorder is not recommended.