You Can Have Amyloid Plaques without Having Alzheimer’s, But . . .

Plaques and tangles (amyloid plaques and neurofibrillary tangles) are the hallmark of Alzheimer’s disease, right? Well, yes – but it seems you can have plaques without any signs of cognitive impairment or dementia. However, in such cases there may be a heightened risk of developing Alzheimer’s later.

A publication in the journal Neuron describes results of examinations on 18 healthy adults under 30, and 35 people aged 60 to 90 who had normal or near-normal scores on the Mini-Mental State Exam (MMSE) and a cognitive impairment screening test. Beta-amyloid plaques were demonstrated by positive emission tomography (PET) imaging after dosing with a special amyloid-related substance, Pittsburgh Compound B.

About 10 older participants with normal and 10 with near-normal cognitive results had amyloid deposits in their brains, equivalent in appearance to those found in patients with dementia. The distribution was more common in those parts of the brain involved in memory tasks. Some of those with such plaques had mild memory impairment, others did not.

These findings suggest that the role of amyloid plaques in relation to Alzheimer’s disease is not clear. However, the study didn’t continue long enough to determine if those with plaques actually developed Alzheimer’s later in life. Obviously there’s still a lot we don’t know.