Alzheimer’s disease can be diagnosed before symptoms appear

Alzheimer’s disease can be diagnosed before symptoms appear

Alzheimer’s disease can be diagnosed before symptoms appear

Abstract: A new study reveals that it is not only possible to determine the risks of Alzheimer’s disease before symptoms appear, but it is also possible to determine whose condition will worsen in the next few years.

Source: Lund University

A major study by Lund University in Sweden has shown that people with Alzheimer’s disease can now be identified before they experience any symptoms. It is now also possible to predict who will deteriorate in the next few years.

The study was published in Natural medicineand it is very timely in light of the recent development of new drugs for Alzheimer’s disease.

It has long been known that there are two proteins associated with Alzheimer’s disease—beta-amyloid, which forms plaques in the brain, and tau, which accumulates inside brain cells at a later stage. Elevated levels of these proteins combined with cognitive impairment were previously the basis for diagnosing Alzheimer’s disease.

“Changes occur in the brain between ten and twenty years before the patient experiences any clear symptoms, and it is only when the tau starts to spread that the nerve cells die and the person in question experiences the first cognitive problems. This is the reason why Alzheimer’s disease is so difficult to diagnose in the early stages,” explains Oskar Hansson, senior neurologist at Skåne University Hospital and professor at Lund University.

Now he led a large international study that was conducted with 1,325 participants from Sweden, the USA, the Netherlands and Australia. The participants did not have any cognitive impairment at the beginning of the study. Using a PET scan, the presence of tau and amyloid in the participants’ brains could be visualized.

It found that people in whom the two proteins were detected were at a 20-40 times higher risk of developing the disease when followed up several years later, compared to participants who had no biological changes.

“When both beta-amyloid and tau are present in the brain, it can no longer be considered a risk factor, but a diagnosis. A pathologist examining samples from such a brain would immediately diagnose the patient with Alzheimer’s disease,” says Rik Ossenkoppele, first author of the study and senior researcher at Lund University and University Medical Center Amsterdam.

He explains that Alzheimer’s disease researchers belong to two schools of thought—on the one hand, those who believe that Alzheimer’s disease cannot be diagnosed until cognitive impairment begins. There’s also the group he and his colleagues belong to—who say that diagnosis can be based solely on biology and what you can see in the brain.

Alzheimer’s disease can be diagnosed before symptoms appear
It found that people in whom the two proteins were detected were at a 20-40 times higher risk of developing the disease when followed up several years later, compared to participants who had no biological changes. The image is in the public domain

“You can, for example, compare our results with prostate cancer. If you do a biopsy and find cancer cells, the diagnosis will be cancer, even if the person concerned has not yet developed symptoms,” says Rik Ossenkoppele.

Recently, positive results emerged in clinical trials of a new anti-Alzheimer drug, Lecanemab, which was evaluated in Alzheimer’s patients. Based on this, the Lund University study is particularly interesting, the researchers say:

“If we can diagnose the disease before cognitive challenges arise, we may eventually be able to use a drug to slow down the disease at a very early stage. Combined with physical activity and good nutrition, we would have a better chance of preventing or slowing future cognitive impairment.

“However, further research is needed before treatment can be recommended for people who have not yet developed memory loss,” concludes Oskar Hansson.

About this Alzheimer’s research news

Author: Press office
Source: Lund University
Contact: Press Office – Lund University
Picture: The image is in the public domain

Original research: Open access.
Amyloid and tau PET-positive cognitively intact individuals are at high risk of future cognitive decline” Rik Ossenkoppele et al. Natural medicine

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Abstract

Amyloid and tau PET-positive cognitively intact individuals are at high risk of future cognitive decline

A major unanswered question in the field of dementia is whether cognitively intact individuals who carry both neuropathological hallmarks of Alzheimer’s disease (ie, amyloid-β plaques and tau neurofibrillary tangles) can preserve their cognition over time or are destined to decline.

In this large multicenter study of amyloid and tau positron emission tomography (PET) (n= 1325), we examined the risk of future progression to mild cognitive impairment and the rate of cognitive decline over time among individuals without cognitive impairment who were positive for amyloid PET (A+) and tau PET-positive (T+) in the medial temporal lobe (A+TMTL+) and/or in the temporal neocortex (A+TNEO-T+) and compared them with A+T and AT groups.

Cox proportional hazards models showed a significantly increased risk of progression to mild cognitive impairment in A+TNEO-T+ (hazard ratio (HR) = 19.2, 95% confidence interval (CI) = 10.9–33.7), A+TMTL+ (HR = 14.6, 95% CI = 8.1–26.4) and A+T (HR = 2.4, 95% CI = 1.4–4.3) group compared to AT (reference) group. Both A+TMTL+ (HR = 6.0, 95% CI = 3.4–10.6) and A+TNEO-T+ (HR = 7.9, 95% CI = 4.7–13.5) groups also showed faster clinical progression to mild cognitive impairment than A+T group.

Linear mixed effect models showed that A+TNEO-T+ (b= −0.056 ± 0.005, T= −11.55, P< 0.001), A+TMTL+ (b= −0.024 ± 0.005, T= −4.72, P< 0.001) and A+T (b= −0.008 ± 0.002, T= −3.46, P< 0.001) groups showed significantly faster longitudinal global cognitive decline compared to AT (reference) group (all P< 0.001). Both A+TNEO-T+ (P< 0.001) and A+TMTL+ (P= 0.002) groups also progressed faster than A+T group.

In summary, evidence of advanced pathological changes in Alzheimer’s disease obtained by the combination of abnormal amyloid and tau PET studies is strongly associated with short-term (ie, 3–5 years) cognitive decline in cognitively intact individuals and is therefore of great clinical importance.

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