Which condition is a slowly progressive decline in mental abilities including memory thinking and judgment that is often acompanied by personality changes?

The condition you're describing is known as dementia. It is characterized by a gradual deterioration in cognitive functions such as memory, thinking, and judgment, often leading to significant changes in personality and behavior. Alzheimer's disease is the most common form of dementia, but there are several other types as well. Early diagnosis and intervention can help manage symptoms and improve quality of life.