Genetic testing for middle-aged individuals could potentially identify a gene implicated in over 90 percent of Alzheimer’s cases, according to a recent study. Researchers emphasize the importance of identifying the APOE gene, which is believed to play a significant role in early cognitive decline, thus advocating for preventive measures during midlife.

Professor Wei Chen, the principal investigator of the study, remarked, “There is increasing evidence linking genetic risk factors to cognitive function alterations in the preclinical stages of Alzheimer’s.” The study’s conclusions underscore the potential benefits of testing for the APOE e4 variant and engaging in focused communication about risks during the middle years of life.

Moreover, the research supports the implementation of certain interventions that could mitigate cognitive deterioration before dementia takes hold. These interventions include adopting a Mediterranean-style diet, engaging in structured cognitive exercises, and maintaining regular physical activity.

The APOE gene has been acknowledged as a crucial factor in Alzheimer’s susceptibility for some time. Recent findings reveal that individuals carrying this gene tend to experience accelerated cognitive decline starting around the age of 70 compared to those without the gene.

‘Several interventions – such as Mediterranean-style diets, structured cognitive training, and regular physical activity – show promise in attenuating cognitive decline before dementia onset.’ 

The APOE gene has long been recognised a major risk factor for Alzheimer’s, but scientists have found carriers of the gene show faster cognitive decline from the age of 70 than non-carriers. 

The study, published in the journal JAMA Neurology, followed 4,392 Taiwanese participants, enrolled on the Health Aging Longitudinal Study. 

Of this, 723 participants carried one copy of the APOE e4 gene, 33 had two copies of the gene and the remaining participants were classed as non-carriers. 

The APOE gene has long been linked to Alzheimer’s, but researchers now say it could speed up cognitive decline, highlighting the need for earlier intervention and testing 

Participants, who were around 68-years-old and dementia free at the beginning of the study, were followed for just over six years. 

Their cognitive function was measured using a screening test called the Mini-Mental State Examination (MMSE) which tests a number of mental abilities including orientation, memory, attention and language skills and returns a score out of 30. 

The higher the score, the better the cognitive function with anything lower than 23/30 indicating mild to severe cognitive impairment. 

Cognitive function was measured both at baseline, during home interviews and study visits by trained professionals, and at follow up, enabling researchers to track changes in cognition over time. 

On average, participants’ scores indicated good cognitive function at the start of the study, averaging a score of 27/30. 

Over the course of the study, participants dropped around 0.2 points per year, totalling a reduction of 1.3 points in just over six years. 

But those with the APOE e4 variant showed faster age-related cognitive decline after the age of 70, especially if they carried two copies of the gene. 

These participants dropped around 2 points by the end of the study. 

Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.

While still generally within the normal range, the researchers said this accelerated decline indicates a higher long-term risk of cognitive impairment as they age. 

Other Alzheimer’s genetic variants, such as the APOE e2 gene which has previously been shown to have a protective effect, did not show measurable effects. 

The researchers concluded: ‘Our results align with prior longitudinal studies demonstrating APOE e4-associated cognitive decline before overt dementia.

‘Approximately 17 per cent of our participants were e4 carriers who might benefit from early counseling and preventive strategies such as Mediterranean-style diets, cognitive training and regular physical activity.’ 

The team hope future research will evaluate the cost-effectiveness of these interventions and define optimal timing and intensity for testing and intervention. 

However they acknowledged their study has some limitations including the fact the cognitive function was only assed with one screening test at two intervals which could lead to an underestimation of cognitive ability.

The findings may also not be generalisable to the general population given the small cohort – which only included a Chinese population – to demonstrate the effects of the APOE gene on healthy aging. 

The researchers were also careful to stress that carrying a high-risk gene does not guarantee that someone will develop dementia. 

Lifestyle and environmental factors can significantly influence risk, with smoking, poor cardiovascular health and social isolation all known to increase the likelihood of developing the memory robbing condition. 

It comes following landmark research published earlier this year which found that the gene could be responsible for more than 90 per cent of Alzheimer’s cases. 

Scientists behind the study suggested if the harmful influence of the gene could be neutralised, up to three-quarters – and possibly more – of Alzheimer’s cases might never develop. 

Dementia is estimated to claim around 76,000 lives a year, making it the UK’s biggest killer. 

Alzheimer’s is the most common form of dementia, affecting around 982,000 people in the UK. Early symptoms typically include memory problems, difficulties with thinking and reasoning, and language issues, which worsen over time.

However, experts believe that around 45 per cent of dementia cases may be preventable – or at least delayed – through lifestyle interventions and improved screening. 

Michelle Dyson, the chief executive of Alzheimer’s society, welcomed the findings saying: ‘We’ve long known that our genes can influence dementia risk, but it’s rare for genetics alone to cause the condition. 

‘APOE is one of the most researched risk genes and having one or two copies of the APOE4 variant raises the likelihood of developing Alzheimer’s disease.

‘This study adds an important piece to the puzzle of how APOE4 may drive cognitive decline, and it’s the first of its kind in a Chinese population. 

‘Most of the previous work in this area has focused on white populations in Europe and the US, so studies like this help us understand whether APOE4 affects people in similar ways across different ethnic groups.’

But she cautioned: ‘The study does have limits. It relies on a single cognitive test, and we don’t know which participants later developed dementia. 

‘And while healthy lifestyle choices can help lower dementia risk, we still need more evidence before recommending APOE4 screening and tailored interventions.

‘Importantly, having a higher risk gene is not a diagnosis. The best way to reduce your risk remains simple: stay active, eat well, avoid smoking, drink within guidelines, and keep socially and mentally engaged.’