People who report early memory problems and whose partners also suspect they have memory problems have higher levels of tau tangles in the brain, a biomarker associated with Alzheimer’s disease, according to a published study. Neurology®the medical journal of the American Academy of Neurology.
Subjective cognitive impairment occurs when a person reports memory and thinking problems before any impairment is large enough to show up on standard tests.
“Understanding the early signs of Alzheimer’s disease is even more important now that new disease-modifying drugs are available,” said study author Rebecca E. Amariglio, PhD, of Harvard Medical School in Boston. “Our study found that early suspicions of memory problems by both participants and people who knew them well were related to higher levels of tau tangles in the brain.”
The study included 675 adults with an average age of 72 years who did not have cognitive impairment on formal testing. They all had brain scans looking for amyloid plaques. Of this group, 60% had elevated levels of amyloid, meaning they were at risk of developing cognitive impairment due to Alzheimer’s disease even though, at the time of the scan, they were cognitively normal. The participants did not know if they had elevated levels of amyloid.
Each participant had a study partner (a spouse, child, or friend) who could answer questions about the participant’s thinking and memory skills and their ability to perform daily tasks. In 65% of cases, couples lived with the participants.
Each participant and their partner completed a questionnaire to assess the participant’s subjective cognitive impairment. Questions included: “Compared to a year ago, do you feel that your memory has decreased substantially?” and “Compared to a year ago, are you having more difficulty managing money?” The scores of the participants and their partners were recorded; higher scores indicated greater memory complaints.
The researchers also reviewed brain scans for levels of tau tangles. Higher tau is also a risk factor for Alzheimer’s disease and is found at higher levels in people with elevated amyloid.
The researchers found that participants with higher levels of tau tangles in the brain had higher complaint scores on the memory questionnaire. Their partners also gave them higher scores. This association was stronger in participants who had elevated levels of amyloid plaques.
“Our study included a high percentage of people with elevated levels of amyloid and, for this reason, we were also able to see that memory problems were associated with higher levels of tau,” Amariglio said. “Our findings suggest that asking older people who have elevated biomarkers of Alzheimer’s disease about subjective cognitive decline may be valuable for early detection. This is particularly important since treatments given in the earliest diagnosable form are predicted to of the disease will be the most effective in slowing the disease.”
Limitations of the study include that the majority of participants were white and highly educated. Amariglio noted that future studies should follow people for longer periods of time and include more participants from other racial and ethnic groups, as well as people with different levels of education.