The Lancet: Blood test can identify signs of Alzheimer’s Disease decades before symptoms, study suggests
Blood test can identify signs of the accumulation of Alzheimer Disease (AD)-associated proteins (biomarkers) in the brains of dementia-free middle-aged adults, suggests a study published The Lancet. The study also finds higher levels of the biomarkers are associated with worse cognitive performance and an accelerated decline in the adults.
AD is defined as a disease that begins with the accumulation of amyloid-beta (Aβ) protein plaques and phosphorylated tau protein tangles in the brain. Recently, measuring the levels of Aβ and tau proteins in blood has become a way to track changes in these proteins, and can be used as a diagnostic tool for AD. Research on these blood tests and biomarkers have mostly focused on older, white adults; little is known about whether AD-associated protein accumulation relates to cognition in midlife and in more diverse communities.
This study measured the levels of the biomarkers Aβ42, Aβ40, and p-tau217 in the blood of 1,350 dementia free adults in the US with an average age of 61 years. Standard high cut-off levels of Aβ and tau associated with AD were identified in 6% (86/1350) of the study participants. High levels of the biomarkers were associated with worse midlife cognitive performance on cognitive processing speed and executive function (brain function which enables planning, focusing attention, and adapting to new challenges) and higher rates of accelerated decline on verbal memory and processing speed tests taken five years apart.
Authors say the study findings demonstrate the potential of detecting early-stage AD among middle-aged adults using blood tests. Early identification of AD would provide an opportunity for the reduction of modifiable risk factors such as physical inactivity, smoking, poor sleep and untreated hearing loss, as well the provision of medication, potentially delaying the start of cognitive decline and development of AD symptoms.
In a Linked Comment, two experts who were not part of the study say that in younger populations with no cognitive impairments the AD-associated protein blood tests can lead to a higher rate of false positive results, therefore additional diagnostic criteria should always be used alongside the blood tests. The Linked Comment authors caution that ‘these blood biomarkers are not suitable for large scale, untargeted screening for Alzheimer’s disease pathology in cognitively unimpaired populations or in the community.’
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The Lancet: New brain scan detects Alzheimer’s Disease biomarkers earlier than current standard, study suggests
A new brain imaging test can detect tau protein tangles - a key biomarker of Alzheimer's Disease (AD) - before symptoms appear and earlier than the method currently used in clinical practice in the United States and Europe, suggests a study published in The Lancet.
AD is defined as a disease that begins with the accumulation of amyloid-beta (Aβ) protein plaques and phosphorylated tau protein tangles in the brain. Early and accurate detection of tau can identify people who are likely to benefit from an anti-amyloid treatment, or to avoid costly and burdensome procedures for people who are unlikely to develop behavioral symptoms of AD.
This study of 682 participants in the USA and Canada with varying ages compared tau PET brain scans, one using the standard tau tracer Flortaucipir and the other with MK6240, a newer tracer primarily used in clinical trial settings. In cognitively unimpaired, amyloid-β-positive participants aged 50-89 years old, MK6240 identified more than twice as many tau-positive cases as Flortaucipir in early tau regions: 54/362 cases for MK6240 (15%) vs 23/362 cases for Flortaucipir (6%). Among cognitively impaired participants, MK6240 also identified more tau involvement (80/282, 28%) than Flortaucipir (46/282, 16%) in late tau regions.
The authors conclude that tau-PET positivity may currently be underestimated, and that the use of more sensitive tau-PET biomarkers can improve detection of early tau pathology and better identify patients most likely to develop AD symptoms.
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The Lancet: MS medication benefits patients with more advanced disease, potentially expanding treatment eligibility, finds trial
Ocrelizumab, a medication already prescribed to some patients with multiple sclerosis (MS)*, also delays the worsening of disability in patients who are older and have more advanced MS, potentially benefiting a wider group of patients than currently receive the medication, finds a study published in The Lancet.
Most clinical trials have failed to identify effective treatments for patients with progressive forms of multiple sclerosis; ocrelizumab is the only treatment to show efficacy in a phase 3 trial. However, the effects of ocrelizumab in patients older than 55 years and/or with more advanced disability, such as requiring a wheelchair, is not known and these patients are often not eligible to receive ocrelizumab.
This new trial enrolled over 1,000 adults with primary progressive MS, aged 18 to 65 years, with disability ranging from mild to quite advanced, to receive either ocrelizumab every six months or a placebo for up to 144 weeks. In the subgroup of predominantly wheelchair-dependent patients, ocrelizumab reduced the risk of disability worsening, such as reduced upper limb and hand function, significantly: 56% (46/82) of patients receiving placebo experienced disability worsening compared to 36% (29/81) of patients receiving placebo.
The trial also confirmed ocrelizumab delays disability progression in MS patients in general, finding 33% (165/505) of patients receiving ocrelizumab experienced sustained worsening of disability lasting for at least 12 weeks, compared to 40% (205/508) in the placebo group.
Authors say maintaining upper limb function is crucial for MS patients in wheelchairs as it allows for maintaining independence and improved quality of life. They say the study findings suggest ocrelizumab could benefit a wider patient population than currently have access to the medication.
*Ocrelizumab is taken every six months to reduce the worsening of disability in primary progressive MS and to reduce the number of relapses in relapsing remitting MS.
The Lancet
People
Alzheimer’s disease neuropathology plasma biomarkers and cognition in midlife: a community-based cohort study
28-May-2026
See paper