How Does Alzheimer’s Diagnosis Work? 3 Things You Need To Know

Despite more than a century of research since Alzheimer’s disease was first described in 1906, diagnosing Alzheimer’s remains extremely challenging for physicians. Researchers are working to make diagnosis more accurate, easier, more accessible, more affordable, and available on a faster timeline. Being Patient sat down with Dr. Marwan Sabbagh, a neurologist and the director of the Cleveland Clinic Lou Ruvo Center for Brain Health to ask him: How does Alzheimer’s diagnosis work?

Sabbagh discussed bottlenecks in the field that hinder clinicians’ ability to accurately identify the disease, and the technological breakthroughs that pave the way for them to diagnose patients with greater precision. Here are three things we learned:

1. A Diagnosis of Exclusion is Notoriously Inaccurate

According to Sabbagh, physicians typically diagnose people with Alzheimer’s by conducting cognitive tests, gathering medical history and family testimonies, and ruling out other conditions that may lead to cognitive decline such as stroke, tumor, thyroid dysfunction, hydrocephalus (abnormal buildup of fluid in the brain) and deficiency of B12 vitamins. 

If a patient’s examinations do not indicate that they have these conditions, then physicians, by default, may determine that their patients’ cognitive issues could be caused by Alzheimer’s or related dementias. 

This is called “a diagnosis of exclusion,” Sabbagh said — a diagnosis of exclusion, as opposed to a diagnosis that includes detecting the presence of the hallmark proteins linked to Alzheimer’s, is imprecise in determining the pathology of the disease. 

“Essentially, we fall into a diagnosis of Alzheimer’s by excluding other conditions, which turns out [to be] notoriously inaccurate in a diagnosis,” he said. “And because of that, physicians don’t feel comfortable making a diagnosis.” 

2. Explaining in Detail About a Loved One’s Symptoms

Patients typically first consult with primary care physicians when they have concerns about cognitive decline. Unfortunately, Sabbagh said physicians often dismiss or downplay people’s complaints. 

However, it is important not to let these concerns go ignored. Sabbagh recommended that, to prompt a doctor to evaluate a loved one’s cognitive abilities and provide a referral to a neurologist, caregivers should be prepared to explain in detail their experience with their loved one’s memory problems. Information such as the duration of their symptoms, whether their cognitive issues fluctuate based on times of day or over periods of time, and whether their symptoms appear to be getting worse can all be helpful in convincing a doctor that cognitive testing is necessary. 

3. There are New Diagnostic Tools in the Horizon

To diagnose people with Alzheimer’s, physicians generally examine their cognitive abilities, medical history and information from family members, as well as exclude other conditions that can lead to cognitive decline. However, without detecting whether the biomarkers of the disease are present in a patient’s brains, an accurate diagnosis remains elusive.

Even though researchers have developed PET scans that detect beta-amyloid plaques and tau tangles, the brain scans are expensive, inaccessible in clinical care and mainly used in research studies. Efforts are now underway to create measures that are cheaper and more accessible than brain scans. Blood tests have shown great promise in the field, as Sabbagh pointed to the blood test developed by C2N Diagnostics, which, as of late this year, is now available to patients for the first time, joining the existing Quest Diagnostics blood test to identify Alzheimer’s biomarkers. 

“The clinical diagnosis accuracy right now is only 70 [to] 75 percent … Study after study after study shows this,” Sabbagh said. With the ability to detect the disease’s presence through biomarkers, he speculated that accuracy will rise to “above 90 percent, without having to massively increase the cost of evaluation,” he said. “I think that’s a win, and can be achieved right away.” 

For more guidance on this topic, subscribe to our newsletter to be the first to know about upcoming live talks with experts on practical topics related to Alzheimer’s, dementia and caregiving.