Gemma Illingworth was only 28 when she was diagnosed with a little-known type of dementia that had silently affected her since childhood. Only three years later, the rare disease had claimed Gemma’s life, leaving her family, who didn’t realize “it was going to be that quick,” completely devastated.
When Gemma Illingworth was growing up in Manchester, her family affectionately described her as “a little ditsy,” quirky, and full of creative energy.
She struggled with telling time, coordination, and visual processing, but no one suspected anything was seriously wrong.
“Maybe we were slightly in denial, I don’t really know, but it was never in our minds that she was actually ill. It was just that she required a bit more support,” Gemma’s sister Jess, 29, told the Mirror. “There weren’t enough tell-tale signs to think that she had such a horrendous disease.”
The tell-tale signs came a little less three decades later and her life took a heartbreaking turn.
Real symptoms appear
During the COVID-19 lockdown in 2020, Gemma’s condition started to appear in a way that no one could ignore.
Isolated and introspective, Gemma noticed her eyesight worsening. At first, doctors attributed her challenges to anxiety and depression, but as her struggles only deepened, the former fashion worker ended up leaving her job in insurance.
Despite wanting to be independent, loved ones watched as the woman became more and more dependent, oftentimes calling her mother Susie up to “20 times a day for support.”
Needed care
“Gemma didn’t fully understand what was going on, and she thought she could live a normal life but she couldn’t… before we knew it, she couldn’t live unassisted,” her brother Ben, 34, said.
Susie would frequently visit her daughter, just to make sure her clothes were on properly and that no appliances were left on.
“This all had to be subtle as I wanted her to have independence for as long as it was safe,” her mom said.
The shattering diagnosis
In April 2021, after increasing concern from her family, Gemma underwent a brain scan. The results revealed there was something “substantially wrong” with her brain.
Initial tests pointed to a possible tumor but after further tests – including more brain scans, cognitive assessments and a spinal tap – doctors delivered a startling diagnosis.
Gemma had posterior cortical atrophy (PCA) a degenerative disease that strikes the back of the brain, “an area responsible for processing visual information.”
PCA
According to the Alzheimer’s Association, there is still no “standard definition” for PCA, nor is there “established diagnostic criteria.” In fact, it is so rare that “It is not known whether posterior cortical atrophy is a unique disease or a possible variant form of Alzheimer’s disease.”
There is also no treatment that’s known to prevent or slow progression.
Gemma was just 28.
‘We can fix it’
While the woman’s family was “devastated” by the shocking diagnosis, Jess recalls that her sister “was ecstatic.”
According to Jess, Gemma thought, “They know what’s wrong with me – we can fix it. She didn’t really understand what it meant, but in a way, that was a blessing in disguise.”
But instead of having it fixed, it gradually stripped away her independence, sense of direction, and eventually, the ability to speak, eat, and move.
Gemma’s condition declined fast.
“Once she had the diagnosis, it was really only going to go one way. We didn’t know it was going to be that quick,” Ben shared.
“It’s the most cruel disease I think in the whole world,” added Jess.
Parts of her remained
Even as the disease gradually stole pieces of Gemma away, the light at her core never fully dimmed – moments of her warmth, humor, and unmistakable spirit continued to shine through, reminding her family of the vibrant woman they loved so deeply.
“Up until the very end, there were parts of her that sort of remained…you could have a lot of difficult hours, but you could still get a laugh out of her,” Ben said. “She had a bit of a wicked sense of humour which definitely didn’t go away.”
Gemma, 31, died on November 27, 2024.
Running for Gemma
But her story didn’t end there.
Her family is determined to turn tragedy into transformation – by raising awareness of young-onset dementia, advocating for early diagnosis, and supporting the organizations that helped them face the unthinkable.
On April 27, 2025 – exactly five months since Gemma died – Jess and Ben, alongside their sister’s best friend Ruth Pollit, ran the London Marathon in her honor – raising more than £20,800 – about $27,800 US – for the National Brain Appeal and Rare Dementia Support (RDS), the organization that helped guide their family.
The team signed up for the marathon while Gemma was still alive and completed other charity fundraisers including a sponsored walk in June 2023, raising £28,000 – about $37,500 US – for the National Brain Appeal.
“We’re trying to raise as much money for RDS so that they can try and prevent stuff like this happening again. They can put their arms around families like ours. They couldn’t cure Gemma, but they helped us navigate it the best way we could,” Ben said.
Jess added that the end goal was to “do it for Gemma, make her proud.”
Please share this story to help spread awareness of PCA and young-onset dementia.
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