How do I know if I have dementia?

People with dementia often don’t recognize they have a problem. So, once you have dementia, you usually can’t self-diagnose it. The stage prior to dementia is known as mild cognitive impairment, when memory and thinking are somewhat impaired but function is normal. With age, people often worry about subjective cognitive decline, when individuals are concerned about their thinking and memory, but both cognition and function are normal.