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As populations age and social stressors increase worldwide, cognitive health has become a pressing public-health concern — especially for older adults. 75% of people living with dementia globally receive no formal diagnosis at all1; the minority who do are then faced with an obstacle course of health system access barriers. Patients frequently face wait times of up to two years for diagnostics2.
A recent community-based study by the Chinese University of Hong Kong reports that nearly 22 percent of people aged 60 and over in Hong Kong have mild neurocognitive disorder (NCD) or mild cognitive impairment, and close to 10 percent meet criteria for major NCD (dementia)2.
These prevalence figures underscore the need for early, proactive care. For clinicians and caregivers, the high rate of mild NCD makes early detection and systematic risk assessment essential to slowing progression and preserving function. Prioritising timely screening, monitoring and intervention can improve outcomes and reduce downstream care burdens.
At the primary-care level, doctors screen for cases using memory tests, and a review of medical history. Blood tests and other diagnostic methods are recommended when the diagnosis is uncertain.
Dr Shea Yat-fung, geriatrician and dementia specialist, says doctors initially ask about different areas of daily functioning to detect mild cognitive impairment.
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“We check communication and language, and we assess executive function — the ability to carry out multi-step tasks, such as following the steps to cook a meal, using an appliance, or going online,” he says. “We also look at skills needed for going out and living independently, like handling money, using public transport and finding your way, or managing emotions. From these questions we decide whether the person can still cope with everyday life. If they can still manage daily activities but show cognitive problems, we call this mild cognitive impairment.”
Diagnostic guidelines
Current diagnostic guidelines rely increasingly on biomarkers — primarily proteins such as amyloid and tau — measured in the bloodstream. Amyloid proteins can clump into plaques in the brain, while abnormal tau proteins form tangles inside brain cells, disrupting neural communication. Supported by biomarker results, doctors can reach a diagnostic conclusion.
Blood tests focus on protein levels, specifically p-tau217, p-tau181 and amyloid-beta 42. Recent international studies indicate that blood tests for p-tau217 can approach the accuracy of lumbar puncture or amyloid PET scans in detecting Alzheimer-related changes, according to Shea.
“When we measure the level of Alzheimer’s disease-related proteins in the blood, the most used methods in Hong Kong are immunology-related techniques because the systems are smaller and more automated,” Shea says. “For now, we generally recommend having these blood tests done at a specialist outpatient clinic.”
“At primary-care level, we need to consider the objective of the blood test — for instance, to rule out the possibility of Alzheimer’s. Then I think it’s worth doing the blood tests,” he continues.
If a primary-care blood test for p-tau217 yields a high negative predictive value, it is very likely the person does not have Alzheimer’s disease; clinicians will then investigate other causes of cognitive problems. “Simply put, when we consider doing these blood tests, the key requirement is that the person truly shows signs of cognitive problems — for example, mild cognitive impairment or dementia. Only in those cases is it worthwhile to perform the tests,” Shea says.
How results are assessed
Doctors use statistical methods to set thresholds for blood tests so they can reliably identify who likely has Alzheimer’s and who does not. These methods can achieve high sensitivity (correctly identifying people with the disease) and high specificity (correctly identifying people without it).
“Referencing the latest medical studies, doctors choose a cut-off value: an upper cut-off and a lower cut-off. Results above the upper cut-off are considered positive, and results below the lower cut-off are considered negative. Values that fall between the two cut-offs form a grey zone. International guidelines explain how to pick these cut-offs. We aim to keep the grey zone fairly small — typically 10 to 20 percent of tested people — which means at most about one in five patients will get an indeterminate result that needs further follow-up,” Shea notes.
If a result falls into the grey zone and the patient wants greater diagnostic certainty, specialists may recommend an amyloid PET scan. Some patients need that extra accuracy because they may be considering specific treatments — such as anti-amyloid antibody therapies — that require a definitive diagnosis. For patients who do not need that level of certainty, repeat blood tests can be used to monitor changes over time.
Amyloid PET scan and spinal tap
A definitive diagnosis of Alzheimer’s disease may require more complex tests, such as an amyloid PET scan, which is costly and limited in availability in Hong Kong. Preparation takes about one hour, and results are usually ready within a week. Costs typically run into ten to twenty thousands of Hong Kong dollars, reflecting the radioactive tracer, specialist staff and equipment involved.
Because new anti-amyloid antibody treatments often require a definitive diagnosis, an amyloid PET scan is commonly requested for patients considering these drugs.
Another option is the cerebrospinal fluid biomarker test obtained via lumbar puncture (spinal tap). This procedure requires careful preparation and is invasive, so it may not suit all patients. Samples are often sent to overseas laboratories; turnaround can take around two weeks. The lab testing itself typically costs a few thousand Hong Kong dollars, but exact prices vary and lumbar puncture is used less commonly than PET scanning in Hong Kong.
The CUHK study2 found Hong Kong’s prevalence of mild cognitive impairment is similar to rates in other Southeast Asian countries. “Some familial cases can start as early as 40 years old. Most early-onset cases that are not inherited tend to appear around age 50; they account for less than 1 percent of patients in our clinic,” Shea notes.
Although an ageing population increases the number of people likely to develop cognitive problems, many cases can be managed. Treatment options include medical therapies (for example, medicines that address vascular problems) and lifestyle changes.
Early identification of cognitive impairment opens a valuable window for non-drug approaches that can help slow cognitive decline and support everyday functioning. or prevention of cognitive impairment, simple lifestyle changes, when adopted early, build resilience and complement medical care. A balanced diet rich in nutrients that support brain health lays a foundation for cognitive well-being, while regular physical activity preserves cardiovascular fitness and promotes blood flow to the brain. Staying socially active and engaging in mentally stimulating pursuits helps strengthen cognitive reserve and maintain everyday abilities.
“Quitting smoking reduces vascular risk and protects brain health, and addressing sensory problems such as hearing or vision loss improves communication and social participation,” Shea notes.
Controlling cardiovascular risk factors — managing blood pressure and cholesterol — is central to prevention. When combined with the lifestyle measures above, some studies report that development of dementia may be prevented or delayed by 40 percent3,4.
“If someone is having memory or cognitive difficulties, I recommend they see a doctor as soon as possible so the doctor can evaluate the situation and determine whether blood tests, scans, or other investigations are needed,” Shea says.
The information provided is intended for informational purposes only and does not constitute medical advice. Always seek the advice of your doctor or other qualified healthcare provider with any questions regarding your medical condition.
- Alzheimer’s Disease International. World Alzheimer Report 2022. https://www.alzint.org/resource/world-alzheimer-report-2022/
- Alzheimer’s Society. People with dementia face up to a two year wait for diagnosis. [Internet; cited Aug 2026] Available from: https://www.alzheimers.org.uk/news/2022-09-23/people-dementia-face-two-year-wait-diagnosis
- Prevalence of mild and major neurocognitive disorders in community and residential care homes in Hong Kong: considerations for multidimensional risk factor evaluation and intervention in primary care. https://www.hkmj.org/abstracts/v32n2/98.htm
- Alzheimer’s Drug Discovery Foundation. Targeting 14 lifestyle factors may prevent up to 45% of dementia cases [Internet; cited Aug 2026]Available from: https://www.alzdiscovery.org/cognitive-vitality/blog/targeting-14-lifestyle-factors-may-prevent-up-to-45-of-dementia-cases
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