Claim: Obesity increases the risk of dementia, as does smoking and diabetes.

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 -LRB- 25 % -RRB- , Lewy body dementia -LRB- 15 % -RRB- , 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 testing with 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 .   There is no cure for dementia . Cholinesterase inhibitors such as donepezil are often used and may be beneficial in mild to moderate disorder . Overall benefit , however , may be minor . There are many measures that can improve the quality of life of people with dementia and their caregivers . Cognitive and behavioral interventions may be appropriate . Educating and providing emotional support to the caregiver is important . Exercise programs may be beneficial with respect to activities of daily living and potentially improve outcomes . Treatment of behavioral problems with antipsychotics is common but not usually recommended due to the little benefit and side effects , including an increased risk of death .   Globally , dementia affected about 46 million people in 2015 . About 10 % of people develop the disorder at some point in their lives . It becomes more common with age . About 3 % of people between the ages of 65 -- 74 have dementia , 19 % between 75 and 84 and nearly half of those over 85 years of age . In 2013 dementia resulted in about 1.7 million deaths up from 0.8 million in 1990 . As more people are living longer , dementia is becoming more common in the population as a whole . For people of a specific age , however , it may be becoming less frequent , at least in the developed world , due to a decrease in risk factors . It is one of the most common causes of disability among the old . It is believed to result in economic costs of 604 billion USD a year . People with dementia are often physically or chemically restrained to a greater degree than necessary , raising issues of human rights . Social stigma against those affected is common .