The Clinical Need

The silent epidemic

Dementia, and in particular late-onset Alzheimer’s disease (AD), has become the silent epidemic of the 21st century and the effort to understand the disease process and develop early diagnostic and therapeutic interventions has been enormous. The global prevalence of AD was 35m in 2010 at a cost of US $604 billion. Today, the total estimated worldwide cost of dementia is US $818 billion, and it will become a trillion dollar disease by 2018[1]. The number of people living with dementia worldwide today is now estimated at 46 million, with this figure set to almost double by 2030 and more than treble by 2050[1]. It is estimated that there are 75m patients with mild cognitive impairment (MCI) who may progress to AD.

Unfortunately, there is no easy method of detection currently available to clinicians to diagnose MCI – or prognostic test to predict progression to AD – before significant brain damage has occurred.

The Health Economic benefits in the United Kingdom have been studied and showed identifying AD patients at an early stage results in cost savings and health benefits. There is clearly, therefore, a need for less expensive, more readily available tests.

Current testing

Memory testing, an example of which, using the Alzheimer’s disease Assessment Scale, cognitive subscale (ADAS-cog) 22, is the primary first line diagnostic test for identifying early stage disease. Although low cost and easily available, to be effective these tests need to be undertaken by experts and many lack sensitivity in the early, milder stages of dementia development and exhibit a high degree of variability in measuring rates of change. The use of PET amyloid imaging has been developed for AD and MCI in recent years. Although this appears to be an effective technique for assessment of amyloid load in the brain, scans can cost up to £10,000 per test depending on location and availability.

Potential impact for patients

Surveys conducted by Harvard School of Public Health on the public perceptions and awareness of AD and early diagnostic testing found that nearly 89% of Americans say that if they were exhibiting confusion and memory loss, they would want to know if the cause of the symptoms was AD[2,3]. Of those aged 60 years and older, 95% say they would want to know if they had AD. Interest in early medical testing for Alzheimer’s disease is high; two thirds of the surveyed adults reported that they would be likely to get an early medical test if one becomes available in the future.

With such support, it is likely that a cost-effective, easily performed prognostic test targeted at MCI patients would be seen as providing significant health economic and clinical benefit, and would therefore stand a good chance of gaining reimbursement, a critical factor underpinning any new diagnostic product development programme.

Potential impact for pharma companies

In the therapeutic arena, the high profile failure in late phase clinical trials of drugs based on the amyloid cascade hypothesis, such as solanezumab and bapineuzumab, has strengthened the interest in improving the stratification of subgroups for enrolment in clinical drug trials. A new biomarker approach would surely find application here too.

References

[1] Alzheimer’s Disease International, World Alzheimer Report 2015: The Global Impact of Dementia

[2] Blendon RJ, Benson JM, Wikler EM. The impact of Experience with a Family Member with Alzheimer’s Disease on Views about the Disease across Five Countries. Int J Alzheimers Dis. 2012, 2012:903645.

[3] Wikler EM, Blendon RJ, Benson JM. Would you want to know? Public attitudes on early diagnostic testing for Alzheimer’s disease. Alzheimer’s Research & Therapy 2013, 5:43.

 

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