Dr Sasha Bozeat
Senior International Medical Manager, Roche Diagnostics
Cerebrospinal fluid biomarkers can accurately predict early stage Alzheimer’s disease1. The earlier the condition is detected, the better the outcomes may be for patients, says one expert.
If you are concerned that you’re developing symptoms of Alzheimer’s disease (AD), you will – understandably – want a speedy and accurate diagnosis to ease your anxiety. Unfortunately, this isn’t always possible.
In fact, diagnosing Alzheimer’s disease can take years in some cases, with around 30% of patients remaining undiagnosed2. That can have devastating consequences says Sasha Bozeat, Senior International Medical Manager at Roche Diagnostics, because, while there’s currently no cure for Alzheimer’s disease, interventions are available that may benefit people with the condition.
“Evidence suggests that making changes to diet while increasing exercise and social interactions can help improve outcomes for those with cognitive impairment3,” she says.
Why clinical practices for diagnosis need improving
However, timely diagnosis is of the essence because, the sooner a patient makes these changes, the more impact they can have on their cognitive performance. The problem is that a patient displaying symptoms of mild cognitive impairment (MCI) may do so for a variety of reasons, and it’s not always clear that they will go on to develop Alzheimer’s disease.
Evidence suggests that making changes to diet while increasing exercise and social interactions can help improve outcomes for those with cognitive impairment3.
When a patient first presents to their GP with characteristic manifestations of memory loss, the doctor may look at their family history and offer cognitive screening in order to decide if they need referral to a specialist. “Yet, at this stage, symptoms may be subtle, particularly among high functioning, well-educated patients,” says Bozeat. “Healthcare professionals do a fantastic job, but it’s easy to see why early symptoms can be missed and diagnosis delayed.”
The additional value of cerebrospinal fluid biomarkers
If a patient is referred to a neurologist, psychiatrist or specialist memory clinic for further investigation, they would likely experience more cognitive testing, and potentially a brain scan and blood tests to exclude treatable causes of their dementia symptoms. In particularly challenging cases where diagnosis is extremely difficult, clinicians may use a cerebrospinal fluid (CSF) biomarker to help them assess the patient – although, typically, this happens late in the diagnostic process.
A CSF biomarker involves taking a sample of cerebrospinal fluid via a lumbar puncture to identify individuals who are amyloid positive. This suggests they may have an increased presence of amyloid-beta in the brain, a protein that is indicative of Alzheimer’s disease4.
Currently, CSF biomarkers are used sparingly, but Bozeat believes they an important diagnostic tool that should be employed regularly. “CSF testing allows a clinician to accurately predict which patients with mild cognitive impairment will go on to develop Alzheimer’s disease5 and enable interventions to take place at that early stage,” she says. “It also rules out patients who are not amyloid positive and who have MCI due to another cause, thereby triggering a different care pathway and set of interventions.”
The future for Alzheimer’s disease identification and treatment
Bozeat thinks there are a number of reasons why CSF biomarkers aren’t used in more cases. Firstly, a lumbar puncture is an invasive procedure that patients and their clinicians would naturally rather avoid; plus, the necessary CSF testing infrastructure – which requires experienced professionals to perform the lumbar puncture, process the assays and interpret the results – isn’t available in some healthcare settings. But the main reason why CSF biomarkers are not used early enough is because no current clinical guidelines exist for the mild cognitive impairment stage of the disease. This needs to change.
“The future of Alzheimer’s disease intervention looks bright,” says Bozeat. “The first disease-modifying therapies are on the horizon and are a major advance. But, again, we know from clinical trials that these types of interventions are most effective when started early, and so identifying the people who need them at an early stage is essential. That’s why I think attitudes towards CSF biomarkers will change, and they will scale up to become an essential part of the diagnostic process.”
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1 Hansson O, et al. Alzheimers dement 2018;14:1470–81 | 2 https://www.dementiastatistics.org/statistics/diagnoses-in-the-uk | 3 Ngandu T, Lehtisalo J, Solomon A, et al. A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial. Lancet. 2015;385(9984):2255-2263. doi:10.1016/S0140-6736(15)60461-5 | 4 Hampel H, et al. Arch Gen Psychiatry 2004;61:95–102; | 5 Hansson O, et al. Alzheimers dement 2018;14:1470–8, van Maurik IS, Vos SJ, Bos I, et al. Biomarker-based prognosis for people with mild cognitive impairment (ABIDE): a modelling study. Lancet Neurol. 2019;18(11):1034-1044. doi:10.1016/S1474-4422(19)30283-2