This form of dementia looks like Alzheimer's disease but is not one – here's what it means

Alzheimer's disease is one of the leading causes of death in the United States and one of the most common causes of dementia in the elderly. Dementia and Alzheimer's disease are often used interchangeably, but dementia is actually a group of symptoms with many causes, including Alzheimer's disease.

In a new study published in the journal Brain, a group of researchers defines the criteria and characteristics of a recently named form of dementia, called predominantly limbic, age-related TDP-43 encephalopathy, or LATE.

Scientists have known about this dementia for many years, but it has only recently been named according to formally defined criteria. The researchers found that TARD is almost as common as Alzheimer's disease in the elderly and that the symptoms seem virtually identical from the outside, but that the inside of the brain seems to be quite different.

Like Alzheimer's disease, TARD negatively affects cognition and makes everyday activities difficult. They discovered that LATE appeared to appear more progressively than Alzheimer's disease, but when combined with Alzheimer's disease, the decline is faster than either.