Dementia is a condition that affects memory, thinking and the ability to perform daily activities. It can be caused by many different diseases that damage the brain. Dementia gets worse over time. Although more common after age 65, it is not an inevitable part of ageing. Things that increase the risk of developing dementia include:

• health conditions such as high blood pressure (hypertension), high blood sugar (diabetes), being overweight or obese, depression, vision and hearing loss, poor sleep, traumatic brain injury and stroke;   
• lifestyle factors such as smoking tobacco, harmful alcohol use, physical inactivity, social isolation, and low educational attainment; and
• environmental factors such as air pollution.

Dementia can be caused by several diseases which over time damage the brain, typically leading to deterioration in cognitive function beyond what might be expected from the usual consequences of biological ageing. The impairment in cognitive function is commonly accompanied, and occasionally preceded, by changes in mood, emotional control, behaviour or motivation. Dementia has physical, psychological, social and economic impacts, not only for people living with dementia, but also for their carers, families and society at large. There is often a lack of awareness and understanding of dementia, resulting in stigmatization and barriers to diagnosis and care.