The Difference Between Alzheimer’s Disease and Normal Cognitive Aging


Greek and Roman philosophers and physicians first referenced senile dementia more than 2,500 years ago. But it wasn’t until 1906, when German physician Alois Alzheimer described a “peculiar case” of presenile dementia, that the medical community began to understand that the disease we now know as Alzheimer’s is anything but a normal part of aging.

A century later, researchers know more than ever before about the biology of aging and Alzheimer’s disease. They are using this knowledge to inform research into potential treatments—and a cure—for Alzheimer’s disease. But despite this incredible progress, more than 59 percent of adults still believe that Alzheimer’s disease is a typical part of aging. This widespread misconception means that many individuals are going undiagnosed and untreated, and that crucial research towards a cure is going unfunded.

What Does Normal Cognitive Aging Look Like?

A person who is aging normally should be able to continue with their normal daily activities. That doesn’t mean that they remain entirely unchanged. Our capacity to process information quickly and remember words and names begins to decline in our 20s. But as we grow older, our vocabulary also grows, our wisdom increases and our emotional resilience grows.

How is Alzheimer’s Disease Different?

When we say that a person has Alzheimer’s disease, we’re really saying that a person has dementia. This clinical syndrome is defined as experiencing mental impairment that is “greater than to be expected for their age” in at least two domains of cognitive function. 90 percent of the time, one of those domains is memory—most often, short term memory. Other domains include language, the ability to do complex motor tasks and the ability to reason and plan abstractly.

For a person with Alzheimer’s, symptoms are progressive and severe enough to cause impairment in daily function. In other words, if a CEO can no longer do his job because he’s lost the ability reason abstractly or multitask, he is experiencing “significant” cognitive impairment.

How Do We Diagnose Alzheimer’s Disease?

Diagnosing Alzheimer’s disease means that we must first eliminate other potential causes of cognitive decline. 50 percent of people with mild cognitive impairment (MCI) will remain stable or improve, while the other 50 percent will progress to dementia in three to five years. For about five to ten percent of people, the root of dementia is a potentially reversible cause—such as depression, thyroid disorders, Vitamin B12 deficiency or polypharmacy (multiple medications).

Fortunately, we have brief psychological tests to determine if a person complaining of cognitive impairment is suffering from MCI or dementia. These nuanced psychological tests are calibrated according to years of education, age and other important factors.

In addition to doing a psychological test, physicians can now order a brain scan—called an amyloid PET scan—which can identify the actual presence of Alzheimer’s disease in a patient even before symptoms have begun. If an amyloid PET scan is negative, a doctor can say with confidence that their patient does not have Alzheimer’s disease.

Why We Need to Know the Difference

When a patient and their caregiver are armed with an accurate diagnosis, they  can better prepare for the long road ahead—making decisions about care planning, ensuring a living will is in place and preparing financially.

They can also exercise, eat a healthy diet, take DHA omega-3 fatty acids and investigate the strength of evidence for other Alzheimer’s and dementia prevention strategies. If they have diabetes, hypertension or other medical risk factors for Alzheimer’s disease, they can carefully manage these conditions.

Moreover, they can get involved in research to help us to find new drugs to prevent and treat Alzheimer’s disease—if not for themselves, than for their children, grandchildren and the 44 million other people currently diagnosed with the disease.