A groundbreaking study has pinpointed a potential early symptom of Alzheimer’s disease that may appear as early as 25 years before more commonly recognized signs, such as memory loss. This discovery could significantly impact how the disease is diagnosed and treated in its earliest stages.

Researchers have uncovered that difficulties with spatial navigation could serve as a precursor to Alzheimer’s, emerging long before memory issues become apparent. This insight offers hope for earlier intervention and more effective management of the disease.

The study, published in the journal Alzheimer’s and Dementia, was conducted by a team at University College London (UCL). The researchers utilized virtual reality (VR) technology to assess spatial navigation skills in participants. A cohort of 100 individuals, all considered to be at risk of Alzheimer’s, navigated through a VR environment using headsets as part of the research.

Participants, aged between 43 and 66, were selected based on their elevated risk factors for Alzheimer’s. These included a family history of the disease, carrying the APOE-ε4 allele—a genetic variant linked to a higher risk of Alzheimer’s—or lifestyle factors such as insufficient physical activity.

Despite their risk factors, none of the participants exhibited any symptoms of Alzheimer’s at the time of the study, and they were significantly younger than the typical age of dementia onset.

The results indicated that those at higher risk for Alzheimer’s showed noticeable difficulties in the VR navigation task, suggesting that spatial navigation impairment could be an early marker for the disease.

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.”