Sign of Alzheimer's disease that can appear '25 years early'

Researchers have identified a symptom of Alzheimer's disease that could manifest 25 years before other signs. While many are familiar with common symptoms of Alzheimer's, such as memory loss, a new study has discovered a warning sign that could appear over two decades prior to the onset of memory loss.

The research revealed that poor spatial navigation could be an early indicator of the disease, appearing 25 years earlier than usual symptoms.

This discovery could facilitate the earliest possible diagnosis of the disease, which is vital for treatment and research into potential prevention methods. As part of the study, published in the Alzheimer's and Dementia journal, scientists from University College London (UCL) asked a group of 100 individuals to navigate a virtual reality environment using VR headsets.

The participants, aged between 43 and 66, were all considered at risk of developing Alzheimer's. This was due to either a family history of the disease, possession of the APOE-ε4 allele gene associated with increased risk, or lifestyle risk factors such as low levels of physical activity.

However, all participants were asymptomatic, showing no signs of Alzheimer's, and were approximately 25 years younger than their medically estimated age for the onset of dementia.

The study's findings revealed that individuals at higher risk of developing Alzheimer's demonstrated "impaired" performance on the VR navigation task.

Yet they showed no similar impairment on other cognitive assessments, including memory tests, indicating that difficulties with spatial navigation could emerge years or even decades before other symptoms appear.

Lead author Dr Coco Newton explained: "Our results indicated that this type of navigation behaviour change might represent the very earliest diagnostic signal in the Alzheimer's disease continuum - when people move from being unimpaired to showing manifestation of the disease.

"We are now taking these findings forward to develop a diagnostic clinical decision support tool for the NHS in the coming years, which is a completely new way of approaching diagnostics and will hopefully help people to get a more timely and accurate diagnosis."

Professor Dennis Chan, who led the study, commented: "We are excited by these findings for two main reasons. First, they improve detection of the clinical onset of Alzheimer's disease, which is critical for prompt application of treatments.

"Second, the VR navigation test is based on our knowledge of the spatial properties of cells in the brain's temporal lobe and the application of cellular neuroscience to clinical populations helps bridge the gap in understanding how disease at the neuronal level can result in the clinical manifestation of disease.

"This knowledge gap currently represents one of the biggest barriers to progress in Alzheimer's research." The study also revealed that men exhibited a stronger impairment in spatial navigation than women.

"This highlights the need for further study of the differing vulnerability of men and women to Alzheimer's disease, and the importance of taking gender into account for both diagnosis and future treatment," Prof Chan stated.

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In addition, Dr Richard Oakley, associate director of research and innovation at the Alzheimer's Society, remarked: "One in three people born today will go on to develop dementia, and early and accurate diagnosis of the diseases that cause the condition are vital for people to access the right support, plan for the future, and receive appropriate treatment.

"Very early symptoms of dementia can be subtle and difficult to detect, but this study shows that problems with navigation could be some of the first changes in Alzheimer's disease."