[Lee Sang-won, President of the Korean Neurological Association] Dementia treatment is changing. With the emergence of drugs that directly reduce the causative substances, the door to treatment has opened. However, many patients are actually stopping right in front of that door. This is because, in order to use the medication, they must first confirm the presence of the causative substances, yet that diagnosis is being blocked in many places. The biggest challenge in dementia care right now is resolving this bottleneck.

The greatest confusion among patients and their families in the clinic stems from a single word: “dementia.” Dementia is not a disease name but a term describing a state of cognitive decline caused by brain disorders, and there are over 100 underlying conditions that can cause it. Among them, the most common is Alzheimer’s disease. It is at this point—distinguishing between dementia and Alzheimer’s disease—that diagnosis, testing, and treatment diverge. This issue of accuracy was also the common thread running through the series of columns I’ve written recently.

Dementia is no longer someone else’s problem. According to the Ministry of Health and Welfare’s Dementia Epidemiological Survey, the prevalence of dementia among seniors aged 65 and older is 9.25%, while the prevalence of mild cognitive impairment—the stage preceding dementia—reaches 28.42%. This means that one in ten seniors has dementia, and more than one in four is in its preliminary stage. In our rapidly aging society, these numbers will continue to rise. Consequently, the importance of accurate diagnosis grows ever greater.

In a recent white paper, the Korean Dementia Society also emphasized that early detection and management of mild cognitive impairment—which carries a high risk of progressing to dementia—is key to reducing the incidence of dementia. For early detection to be effective, accurate diagnostic tools must be accompanied by a proper understanding of them.

If you visit a neurologist due to memory concerns, the process does not end with a single test. First, the doctor reviews your medical history and uses neuropsychological tests to assess the degree and nature of cognitive decline. Blood tests screen for reversible causes, such as thyroid dysfunction or vitamin deficiencies. Computed tomography (CT) and magnetic resonance imaging (MRI) examine the brain’s structure to identify abnormalities like tumors or strokes. Only after these steps have been completed and it is necessary to directly identify the causative agent of Alzheimer’s disease is amyloid positron emission tomography (PET-CT) used. Since each test examines different aspects, skipping steps is not advisable, and undergoing the most expensive test from the start does not guarantee an accurate diagnosis.

Beta-amyloid, the causative agent of Alzheimer’s disease, gradually accumulates in the brain 15 to 20 years before symptoms appear. While structural imaging cannot detect these changes, amyloid imaging allows for their visualization in living patients. Studies comparing this test with autopsy results have reported sensitivity and specificity of around 90% each. Treatments targeting the causative agent are most effective when administered at an early stage. This is why it is crucial to determine whether the underlying cause of mild cognitive impairment—a condition that is neither normal nor dementia—is Alzheimer’s disease. However, not all cases of mild cognitive impairment progress to dementia, and a single positive test result does not necessarily confirm a diagnosis of dementia.

Even with the same cognitive decline, the causes can vary. Depression in older adults may resemble dementia but often improves with treatment. Nor does a family history guarantee the onset of the disease. Only a small proportion of Alzheimer’s cases are directly inherited from parents, and a significant portion of risk factors can be managed through lifestyle changes. The test provides information to help determine the right path at this crossroads; it is not a conclusion in itself.

This diagnosis is the gateway that must be passed to use new treatments. Before starting medication, the presence of amyloid must be confirmed, and this confirmation is done through PET scans or cerebrospinal fluid tests. Since these drugs slow progression rather than reverse it, identifying the right patients is all the more critical.

An incorrect diagnosis harms patients in two ways. If a treatable condition is mistakenly diagnosed as dementia, the opportunity for recovery is lost; conversely, if anti-amyloid drugs are administered to someone who does not have Alzheimer’s disease, the patient bears the risk of side effects without any benefit. An accurate diagnosis reduces both unnecessary treatment and anxiety.

This is why using terminology accurately is so important. Although commonly referred to as “dementia drugs,” these medications are intended for patients with Alzheimer’s disease. The phrase “early diagnosis of dementia via PET-CT” is also inaccurate. Since dementia is a condition where cognitive function has already declined, it is not a target for early diagnosis; what this test identifies is not dementia itself, but the causative agent of Alzheimer’s disease. Using the correct terminology helps reduce confusion for both patients and medical staff.

However, an increase in testing does not necessarily lead to more accurate diagnoses. We must be cautious about recommending “early dementia screening” to people who show no symptoms. Amyloid testing is not a screening test for everyone, but rather a test for patients who need it. As long as the term “dementia” is used in marketing to instill fear, accurate information remains the most reliable defense.

This is the root of the bottleneck mentioned earlier. While demand for diagnosis is growing rapidly, the infrastructure for testing and the supply of radiopharmaceuticals cannot keep up. To resolve this bottleneck, the Korean Neurological Society has partnered with the domestic radiopharmaceutical company #DuchemBio. The purpose of this agreement is to expand access to early diagnosis for neurological diseases such as Alzheimer’s and Parkinson’s. The key is to create a seamless care environment where patients can be referred from nearby private neurology clinics to partner hospitals equipped with PET-CT scanners. To achieve this, the association plans to implement a phased approach involving the certification of partner hospitals, support for testing infrastructure, and the integration of care pathways, while also operating educational programs for neurologists.

There is also much that families can do. It is helpful to keep a record of when symptoms began and how they have changed over time, and to accompany the patient to appointments to listen to the explanation together. Managing controllable risk factors—such as blood pressure, blood sugar, exercise, and sleep—serves as a consistent precaution, regardless of family history.

A diagnosis is not the end but the beginning. If the result is positive, we discuss treatment and follow-up plans; if negative, we proceed to investigate other causes. Looking back, the questions patients ask are similar: Is it just simple forgetfulness? What tests should I undergo? Should I get tested even if I have no symptoms? What should I do if there is a family history? The answer converges on one point: to diagnose accurately and ensure that the necessary tests are performed in a timely manner for those who need them.

What neurologists hope for from patients is simple: rather than immediately thinking of tests when forgetfulness becomes a concern, they should first consult a doctor to determine the stage of the change. Using the correct terminology and receiving necessary tests at the right time—that is the path to navigating the era of dementia.