Researchers have identified a new form of dementia that is often misdiagnosed as Alzheimer's disease. The brain disease could even be more prevalent than Alzheimer's among older adults.

Dementia Not A Single Disease

Dementia is not a single disease but rather a name for a group of symptoms characterized by problems with memory and thinking.

There are different types of dementia, but Alzheimer's disease is believed to be the most common and most studied.

Alzheimer's causes loss of cognitive functions, which leads to changes in everyday functional abilities and behavior. In the past, most dementia cases with memory loss were assumed to be Alzheimer's disease.

Researchers of a new study published in the journal Brain on Tuesday, however, say that up to a quarter of people over the age of 85 have may have limbic-predominant age-related TDP-43 encephalopathy, or LATE, albeit the two forms of dementia can coexist.

Symptoms Of LATE Mimic Alzheimer's

The condition often mirrors the symptoms of Alzheimer's disease, but it has different effects on the brain. It also develops more slowly compared with Alzheimer's.

Doctors said that the two are often found together, and when they do, the patients may experience a steeper decline in cognition.

"LATE-NC is a common TDP-43 proteinopathy, associated with an amnestic dementia syndrome that mimicked Alzheimer's-type dementia in retrospective autopsy studies," Rush Alzheimer's Disease Center associate director Julie Schneider and colleagues wrote in their study.

TDP-43 Protein

Unlike people with Alzheimer's disease, those with LATE do not accumulate beta-amyloid or tau proteins in their brains. In patients with LATE, a certain protein called TDP-43 accumulates in the brain.

TDP-43 normally helps regulate gene activity in the brain, but misfolded or abnormally structured TDP-43 has been implicated in rare diseases such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

Recent study showed that misfolded TDP-43 protein is prevalent in older adults. Up to 25 percent of those age over 85 have enough misfolded TDP-43 protein that can affect their memory and thinking abilities.

"We proposed a new name to increase recognition and research for this common cause of dementia, the symptoms of which mimic Alzheimer's dementia but is not caused by plaques and tangles," Schneider said. "LATE dementia is caused by deposits of a protein called TDP-43 in the brain."

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