Alzheimer’s disease: Symptoms & Diagnosis

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In honor of World Alzheimer’s Day yesterday, I wanted to share a little bit about the diagnostic process of Alzheimer’s disease (AD). I often receive questions about whether changes in thinking are due to normal aging, due to a neurodegenerative process like AD, or due to something else entirely! 

Background Information

First, a bit of context. AD is one of many different types of dementia. Seventy percent (70%) of dementia cases are due to AD, so this represents the largest category of dementias by far. Women are at higher risk of developing AD, with a 1 in 6 chance of developing it compared to a 1 in 11 chance in men. The average age of diagnosis is around 74 years, with most individuals diagnosed with AD between 70 and 79 years of age.

Neuropsychologists can diagnose AD based on what we call the “behavioral presentation” of the person, or the behaviors that we observe in working with the person and based on scores from standardized testing.  However, the specific kind of dementia is typically confirmed via autopsy after the individual has passed away. This is why you may hear the doctor say this is “probable AD,” or that the behaviors are consistent with “possible AD.”  

In AD, neuropathologists are looking for beta amyloid deposits (also known as plaques) or tau neurofibrillary tangles/neuropil threads (tangles). Often, there are multiple contributors to cognitive decline or a “mixed pathology,” meaning the person may have AD plaques and tangles, but also vascular changes to their brain, for example. 

Behavioral Presentation

So what behaviors do we observe in individuals who have probable AD? Commonly, a person comes to the office due memory loss. The person may not notice these changes themself, but may be brought for evaluation by a family member or caregiver who has noticed the person is repeating stories or forgetting information. The changes are slow, and the later in life the person is when symptoms arise, the slower the typical progression of cognitive decline. 

Nonetheless, we may see difficulties learning and remembering new information over a short period of time. We call this “rapid forgetting.” Now, though memory concerns are the most common presentation, individuals may present with language deficits (logopenic PPA), spatial difficulties (PCA), or impairments in executive functioning (frontal variant). All of these particular dementias are caused by the same thing, plaques and tangles, but the deposits are found in different parts of the brain and thus they have different names. The neuropsychological evaluation process teases apart these various forms of dementia (and others!) based on behavior in order to guide intervention.  

Changes in memory or other thinking skills also impact the person’s ability to independently complete daily living tasks. This means the person may need assistance getting dressed, paying bills, or keeping track of appointments. They may no longer be safe driving independently, or may need reminders of important events or scheduled activities.

Do We All Have AD?

So does every person with memory loss have a dementia, or AD? The short answer is absolutely not. Changes to thinking and memory are normal parts of aging, and thus the neuropsychological evaluation can identify whether the changes are expected for a person’s age, or if they reflect a neurodegenerative condition. Additionally, sometimes common medical conditions or psychological diagnoses (such as depression) can mimic cognitive change, but when those symptoms are treated the individual’s cognitive abilities once again improve. 

Empowerment & Intervention

As you can see, there are many pieces to pull together in order to make an accurate diagnosis, and sometimes it takes monitoring cognition over time to clarify the most appropriate diagnosis. Empowered with answers, families who seek out a diagnosis can then put support plans in place, explore medications options, or engage in lifestyle changes that are shown to improve cognition. It is never too early to intervene!  

To learn more about the neuropsychological evaluation process for older adults, please click here. If you are looking for research supported strategies to boost cognitive wellness at any age, check out my colleague’s book High Octane Brain