Understanding an Alzheimer's Diagnosis: What the Process Actually Involves

An Alzheimer's diagnosis is rarely a single test or a single visit; it's a process, and understanding it can ease some of the fear that comes with it.

Carol brought her husband, Frank, to see me because she couldn't tell whether what she was seeing was normal aging or something more. He'd always been the one who remembered birthdays and paid the bills without fail. Lately, he was forgetting conversations they'd had that same morning, and he'd stood at the stove one evening, staring at a pot of rice as if he'd never made it before in his life.

"Is this just getting older?" Carol asked me. "Or is this something I should be worried about?"

It's one of the most common questions I hear in my practice, and it deserves more than a quick answer. So this month, I want to walk you through something that too few families understand well: how an Alzheimer's diagnosis is actually made, why it's more complicated than most people assume, and what the process can and can't tell you.

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The Brain Is Like a Computer — But It Isn't

I often explain it this way to families. The brain is like a computer, though it's far from an ordinary one. A brand-new computer, just like a child's brain, absorbs information rapidly and returns it just as quickly. Over time, a computer stores more information, and it takes longer to sort through it all. That's a decent explanation of an aging brain. It holds decades of stored information, so retrieval takes more time. That's why a name will finally surface after a long search.

But the brain isn't a computer. It's alive, and it improves with exercise. Even in advanced age, the brain keeps learning and keeps growing.

The brain performs three essential functions that dementia can affect. It feels and expresses emotion. It learns and remembers, storing a lifetime of experience. And it governs our physical abilities, letting us move, speak, and carry out an ordinary day.

An aging brain and an injured brain are not the same thing. Age slows how we process information, but it doesn't damage the systems that let us feel, remember, and function. Dementia works differently. It injures the brain over time, disrupting these functions well beyond the ordinary pace of aging. That distinction is the starting point for understanding an Alzheimer's diagnosis.

The Cognitive Gray Zone

Certain changes fall well within normal aging. Taking a bit longer to recall a name, only for it to surface later. Misplacing keys or glasses in the shuffle of a busy day. Needing more time to process new information. These reflect a natural slowing of cognitive processing. The brain keeps functioning well; it just asks for more patience.

Other changes warrant a conversation with a healthcare provider. Memory loss that disrupts daily life. New difficulty with tasks that were once second nature, like preparing a familiar meal. Confusion about time or place that goes beyond an occasional lapse. Trouble following a conversation. Struggling to find words. Judgment that seems compromised. A withdrawal from work or social life that seems driven by more than preference. These findings, especially if persistent, suggest Alzheimer's disease or another form of dementia.

If something feels different from the normal slower pace of an aging brain, that observation deserves attention, not because every case leads to a diagnosis, but because clarity, whatever it reveals, gives a family a foundation to move forward from.

How an Alzheimer's Diagnosis Is Actually Made

For many decades, and to some degree even now, an Alzheimer's diagnosis has rested primarily on a physician's clinical impression. That approach is imperfect in both directions. There have been cases where people were diagnosed with Alzheimer's when more thorough evaluation was warranted, and — more commonly — cases where the diagnosis was missed. Part of the difficulty lies in how subtle the disease can be in its milder stages.

In practice, clinicians diagnose based on several converging features: a progressive decline in cognition and memory, a decline that meaningfully interferes with independence in everyday activities, and the careful exclusion of other medical, neurological, or psychiatric conditions that might explain what's being observed.

The evaluation draws on several tools. Standardized cognitive testing, including memory assessments like the clock drawing test, in which a patient draws a clock face and places the hands at a specified time. Laboratory testing to rule out treatable contributors like thyroid disorders or vitamin B-12 deficiency, both of which can mimic cognitive decline. Neuroimaging, whether CT or MRI, to identify a prior stroke or other structural cause.

The picture grows more complicated still. Some patients live with both Alzheimer's disease and coexisting conditions, like depression or a history of stroke, that cloud the clinical picture further. I once cared for a woman who was a scientist and also lived with depression. Her standardized cognitive testing came back entirely within normal range. By every conventional measure, nothing appeared amiss. Yet she was having growing difficulty using instruments and methods that had once been second nature in her professional life. Over the following months, it became clear that what we were witnessing was Alzheimer's disease, quietly progressing beneath results that told us otherwise.

Her case illuminates something I think about often. Standardized tests carry real value, but they were never designed to capture everything that matters. How a person actually functions in the fullness of their life sometimes reveals changes long before a test administered in a clinical office ever will. If you notice a change in someone you love that the testing doesn't seem to reflect, trust what you're seeing. You understand this person's baseline in a way no examination room ever will. Bring specifics to their physician. Diagnosis unfolds over time and conversation, not in a single visit.

Blood Tests Are Changing an Alzheimer's Diagnosis

This year brought genuinely encouraging news: reliable blood tests are now approved and available in clinical laboratories. For a long time, the field lacked a truly accessible way to diagnose Alzheimer's disease with confidence. Sophisticated brain imaging and spinal fluid analysis have served research and specialized clinical settings well, but both remain invasive, costly, or difficult to access for most families.

The Lumipulse test, cleared in 2025, measures specific proteins associated with amyloid plaques in the brain and is used in specialized settings such as memory clinics. The Elecsys pTau181 test is cleared for primary care settings and functions as an initial rule-out tool, helping determine when amyloid pathology is absent and sparing many patients from unnecessary specialized follow-up testing. For the first time, a family physician, not only a neurologist, can incorporate blood work meaningfully into an Alzheimer's diagnosis.

One caveat deserves emphasis. Neither test is approved for routine screening in people without symptoms. Both are meant to accompany standard cognitive evaluation, medical history, and clinical judgment, not replace them. Still, they offer a far less invasive alternative to spinal taps or PET imaging.

That raises a real question I sit with in the exam room: should we simply test everyone, the way we routinely check blood pressure? For now, the consensus among experts is no. A borderline result can trigger genuine distress without offering much clarity, and unlike hypertension, we don't yet have a treatment that reliably reverses or substantially slows the underlying disease once it's found. Some patients would want to know years in advance. Others would say living with that knowledge, absent any ability to change the outcome, isn't worth the weight it adds. Both responses make complete sense to me.

Mild Cognitive Impairment: The Middle Ground

Mild cognitive impairment, or MCI, is a term doctors reach for when the evidence points toward some cognitive change without yet crossing into a full Alzheimer's diagnosis or another form of dementia. Memory or thinking declines measurably, but it doesn't yet interfere with everyday independence.

Roughly ten to fifteen percent of people with MCI progress to Alzheimer's disease each year. Many others never develop the disease at all, and in some cases, cognition even improves, particularly when an underlying cause proves treatable, a medication side effect, an untreated sleep disorder, or significant stress. The new blood tests are making a real difference here too. A positive result makes it very likely a person has evidence of Alzheimer's disease, though a person can still have dementia without a positive result; vascular dementia, most commonly, isn't diagnosed by these tests.

The GOLD Approach to Diagnosis

When families are moving through this process, I recommend the GOLD approach:

Gather a thorough evaluation. Don't settle for a quick clinical impression alone. Cognitive testing, lab work, and imaging each tell part of the story.

Observe and trust your own instincts. You know this person's baseline better than any examination room ever will. Bring specifics, not just impressions, to the physician.

Lean on new tools when they help. Blood tests are reshaping what's possible, but they're meant to accompany judgment, not replace it.

Dignity and hope, regardless of what the diagnosis reveals. A diagnosis is information that opens a path forward, not a verdict.

Diagnosis as a Path Forward

When Carol brought Frank back for his follow-up, the blood test alongside his cognitive evaluation confirmed what we suspected. She cried in my office, but not entirely from grief. "At least now I know what we're dealing with," she told me. "I can stop wondering if I'm imagining things."

That's really the heart of an Alzheimer's diagnosis. It isn't a verdict. It's information that opens a path forward — toward understanding, toward planning, and toward living with as much love and dignity as the circumstances allow, whatever the diagnosis ultimately reveals.

Warmest Aloha,

Dr. Warren Wong

PS: I say it over and over again: There's no one more important than the caregiver in the daily life of a frail person.