Three and a Half Years: Why Dementia Takes So Long to Diagnose — and What That's Costing Us

Age Brightly Blog | Dementia Series, Part 4 of 5 Featuring Dr. Cheryl Johnson, Lead Geriatrician at Age Brightly

The average time between a person first experiencing symptoms and receiving a dementia diagnosis in New Zealand is three and a half years.

That's a long time to be scared and uncertain. A long time for a family to be managing something they can't name. And with treatments like lecanemab emerging that only work in the early stages, it's a window that can quietly close while people wait.

So what's behind the delay — and what can be done?

The attitude problem

Part of the issue is cultural. Dr. Johnson is direct about it: "I think we need to change the narrative. We say 'oh, you're just getting old, so it must just be part of getting old.' But maybe it isn't. Maybe this is actually a problem we need to address."

Memory changes in older people get normalised in a way that other symptoms don't. A patient comes in worried about their recall, and they're told it's just aging. They come back again. Same answer. The niggle remains, but the clock keeps ticking.

The masking problem

Dementia — Alzheimer's in particular — has a way of hiding itself. People become skilled at talking around gaps, keeping up appearances, staying on familiar social ground. Partners and carers may notice something is wrong at home, but in a clinical appointment, everything looks fine.

"Lots of people do mask their cognitive problems," Dr. Johnson says. "They'll just sort of talk over it. 'You know, there's nothing to see here. Everything's fine.' And the carer in the background is just going..." She doesn't need to finish the sentence.

Some people don't even know they're masking. A particular subset of people with Alzheimer's lose what clinicians call insight — the ability to recognise that something is wrong. They genuinely believe they're fine. This isn't deception; it's a feature of the disease itself.

It makes the carer's account essential — and makes the diagnostic conversation considerably more complex.

What diagnosis actually involves

Getting a diagnosis requires getting in front of the right person: a geriatrician, psycho-geriatrician, or specialist in geriatric medicine. The process involves:

A detailed history — covering functional changes like managing money, medications, cooking, driving, self-care. The specialist needs to hear from both the person and, where possible, the people around them.

A cognitive assessment — tests that look at which areas of brain function are working well and which aren't, helping to narrow down the subtype of dementia.

Brain scanning — either MRI or CT, looking for atrophy (shrinkage), strokes, and which regions of the brain are most affected.

Then comes the conversation — which Dr. Johnson believes should be honest and direct, regardless of how hard the word "dementia" is to say. "I'm a very strong believer in honesty. I think we do a disservice when we don't use the right terms."

What the delay is actually costing

People sometimes reason that there's no point knowing — so why rush? Dr. Johnson identifies several reasons why this logic backfires.

Opportunity cost. With new treatments emerging that are most effective in the earliest stages, every year of delay shrinks what's available. "We've got a window, and that window is closing."

Treatable conditions being missed. Not everything that looks like dementia is dementia. Vitamin B12 deficiency impairs nerve function and can mimic cognitive decline — treat the deficiency, and the symptoms resolve. Thyroid disorders can do the same. Without a proper assessment, these go unaddressed.

The toll on carers. Families managing an undiagnosed situation have no framework, no strategies, and no specialist support. They're managing behaviour changes they can't explain, fielding well-meaning relatives who say everything looks fine, and running on empty.

"There's a huge cost on the carer and the family," Dr. Johnson says. "They're having to manage all these issues and all the stress without really understanding what's going on, or having someone who can walk alongside them."

What early looks like

A confident early diagnosis — done well — is not a sentence. It's information. It's a roadmap. It's the thing that unlocks treatment, support, and planning.

"As awful as it is for some people to be diagnosed," Dr. Johnson says, "there's a group for whom it's almost a relief. They've had this sense that something isn't right, and having the diagnosis means they know what they're dealing with. Now they can make a roadmap."

That's what Age Brightly is working toward: not just helping people get diagnosed, but walking alongside them through everything that comes after.

Next in the series: What you can actually do to protect your brain — the lifestyle factors with real evidence behind them.

Most of it is preventable. But not the week before. Now.