When most of us think about dementia, we picture an older person struggling to remember names or where they put their keys.
That’s part of it, for sure, but dementia is actually an umbrella term for over 100 different conditions, and a large chunk of them have nothing to do with memory at first. Some affect vision, and some change how a person speaks. Others change personality so dramatically that families don’t recognise the person they’re living with.
Around 15% of dementia cases don’t follow the typical pattern most people expect, and many of them impact people in their 30s, 40s and 50s. Because the symptoms look so different, they often get put down to stress, depression, or in women, menopause. It can take three and a half years on average to get a proper diagnosis, sometimes much longer. That’s a long time to be struggling without answers, and it matters that more people know these conditions exist.
Frontotemporal dementia changes who a person seems to be.
Frontotemporal dementia, usually called FTD, affects the front and sides of the brain rather than the parts associated with memory. What it changes first is personality and behaviour, which means the early signs can look like a midlife crisis, relationship problems, or just someone “acting differently.” Families describe a person losing their empathy, laughing at inappropriate times, or becoming almost unrecognisable in how they treat people around them.
Some people with FTD develop what feels like an absence of brakes on their behaviour. They often start saying things they’d never normally say, shoplifting, touching strangers, or becoming fixated on sweet foods. Because the person themselves often has no insight into what’s happening, it’s usually family members who piece things together and push for a diagnosis. It can start in someone’s 30s and is sometimes inherited, which brings its own painful layer of complexity for families who’ve already watched a parent go through it.
Some types of dementia take away language instead of memory.
Primary progressive aphasia, known as PPA, is a group of conditions where language is the first thing to go. The actor Bruce Willis was diagnosed with it in 2022, which brought it a lot of public attention. People with PPA might start struggling to find words, pausing mid-sentence while they search for something that feels just out of reach. In other cases, speech becomes slow and physically difficult, or words come out in the wrong order.
There’s another type called semantic dementia, where the meaning of words starts to disappear. Someone might ask “what’s breakfast?” when you mention it, not because they’ve forgotten eating that morning, but because the concept itself has become unclear to them. They can often still speak quite fluently, using vague filler words because the specific ones are gone. It’s a strange and heartbreaking thing to witness, and because memory can seem relatively intact, it often gets missed for a long time.
Posterior cortical atrophy affects vision without anything being wrong with the eyes.
This one is particularly likely to get missed because the person’s first symptom is often trouble seeing, so they end up at an optician rather than a neurologist. Glasses don’t help because the problem isn’t with the eyes themselves. The brain is receiving the visual information but not processing it correctly, so things like judging distances, reading, or finding a stationary object in a room become really difficult.
There was a case of a man in his 50s who first noticed something was wrong because he couldn’t track a shuttlecock when it stopped moving during a badminton game. He could see it mid-flight but lost it completely when it landed. Others describe struggles with driving, parking, or reading. The average age of diagnosis is 58, but it’s been seen in people as young as 25. In more than 90% of cases, the underlying cause is Alzheimer’s disease, just presenting in an unexpected way.
Lewy body dementia is more common than most people realise
Lewy body dementia accounts for up to 10% of all dementia cases, which makes it far from rare, but it’s still one of the less talked about types. It’s caused by protein deposits called Lewy bodies building up in the brain, and the symptoms are a mix that can make it confusing to diagnose. Memory and thinking are affected, but so is movement, in ways that look similar to Parkinson’s disease, with slowness, stiffness, and tremors.
One of the more striking features is vivid visual hallucinations. People see things that aren’t there, often children or small animals, with complete clarity. There are also cognitive fluctuations where someone might seem quite sharp one hour and extremely confused the next, sometimes within the same day. Some existing dementia and Parkinson’s medications can help manage the symptoms, and trials are underway looking for ways to slow its progression.
Familial Alzheimer’s is the inherited form that can strike young.
Less than 1% of Alzheimer’s cases are directly inherited, but for those families it’s an enormous weight to carry. A parent with the gene mutation has a 50/50 chance of passing it on, and if it’s inherited, the person will almost certainly develop the condition. Symptoms can begin in someone’s 30s, 40s or 50s, which means people may be raising children or in the middle of their working life when things start to change.
The particular difficulty for people living with this risk is that they might be caring for a parent with the condition while simultaneously wondering whether it’ll happen to them. Research involving these families is important because scientists can study what happens in the brain before symptoms even appear, which opens up the possibility of one day slowing or preventing the disease before it takes hold.
Getting diagnosed with a rarer dementia is a long road.
Around 30% of people with a rarer form of dementia initially get the wrong diagnosis. That’s not a small number, and it means years of being told it’s anxiety, burnout, hormones, or depression, while the actual cause goes unaddressed. Part of the problem is that these conditions are still not well known enough even within medicine, and part of it is that the symptoms can look like other things, especially in someone who seems too young for dementia.
If something feels consistently wrong and the explanations you’re being given don’t quite fit, it’s worth pushing for specialist assessment. Conditions like these are diagnosed through a combination of neurological exams, cognitive testing, brain imaging and sometimes spinal fluid tests. The right diagnosis doesn’t cure anything, but it changes everything in terms of understanding what’s happening, finding the right support, and accessing the right information for the future.
There are things that genuinely help reduce the overall risk.
While a lot of the rarer dementias have genetic or biological causes that are outside anyone’s control, dementia risk overall is influenced by lifestyle in meaningful ways. Regular physical activity, even just aiming for around 7,000 steps a day, supports brain health through its effect on the heart and circulation. Stopping smoking makes a real difference, it’s one of the most clearly identified modifiable risk factors. Cutting back on alcohol matters too, and recent research suggests there isn’t really a safe level when it comes to brain health.
Eating well, keeping weight in a healthy range and managing conditions like diabetes all reduce risk. And one that surprises people: untreated hearing loss is a major risk factor for dementia, with some evidence that using a hearing aid where it’s needed may actually slow cognitive decline. None of these are guarantees either way, but they’re worth taking seriously, particularly given how much the earlier stages of dementia can go unnoticed.
