What is the term for a progressive and irreversible decline in mental function accompanied by changes in mood and behavior?

Dementia is the term that describes a progressive and irreversible decline in mental function, which includes memory loss, difficulty in reasoning, and changes in mood and behavior. It involves a wide range of cognitive impairments that significantly affect a person's daily life and ability to function independently. Alzheimer’s disease is actually a specific type of dementia and is the most common cause, but dementia itself encompasses various forms and causes beyond just Alzheimer's.

As individuals with dementia progress through various stages of the condition, they may exhibit changes in personality, emotions, and social skills, which further distinguishes it from other cognitive issues like amnesia, which primarily affects memory recall without the broader cognitive decline. Cognitive impairment is a broader term that can refer to a range of conditions affecting cognitive function, but it does not specifically imply the progressive and irreversible nature that defines dementia.