Dementia is a progressive condition. There are 3 main stages: early dementia, moderate dementia, and advanced dementia.
In the early stages, they may start to change in small ways. Losing motivation, joy and forgetting a few things is common. They may blame you for stealing lost items.
By the moderate stages of dementia, their behaviour and actions become more unusual and inappropriate. They may get lost easily, forget names, or find themselves easily perplexed.
The later stages involve far more severe loss of function. Your loved one may struggle to do basic tasks by themselves, such as dressing, going to the toilet, speaking or walking. They might become aggressive, and completely change personality.