They’re two words you might never think to put together, but the sad truth is that childhood dementia affects an estimated 700,000 young people across the world. In many ways, the condition mirrors the various types of dementia that we’re familiar with in adults; but the unusual causes, not to mention the age of the patients affected, make this a very different medical mountain to climb.
What causes childhood dementia?
For most types of dementia, such as Alzheimer’s disease, the symptoms only begin to arise in adulthood. Apart from a few exceptional cases, these conditions tend more to be the preserve of geriatric medicine. So how is it that children can also be affected?
Unlike with adult dementia, the causes of which remain a very active area of research, scientists know of at least 70 different genetic conditions that can lead to childhood dementia. According to the Childhood Dementia Initiative, one in 2,800 babies are born with one of these conditions.
These genetic disorders fall into a multitude of different categories. They may all be associated with different combinations of symptoms, but the thing they have in common is the ability to cause a dementia-like progressive illness. Here’s a deeper dive into just a few of these disorders.
Mucopolysaccharidosis, or MPS, arises when the body is missing enzymes that break down certain carbohydrates called glycosaminoglycans, or when these enzymes don’t work properly. Four different MPS subtypes have been associated with childhood dementia. As the glycosaminoglycans are not broken down correctly, they can build up in cells and tissues over time, causing damage.
Canavan disease is a rare example of a broader group of conditions known as leukodystrophies. These abnormalities affect the white matter, the tissue in the brain that’s made up of all the nerve fibers. In children with Canavan disease, the white matter starts to break down and takes on a sponge-like appearance.
Tay-Sachs disease made headlines last year when two children became the first ever to receive gene therapy for the condition. People with Tay-Sachs do not make enough of an enzyme called beta-hexosaminidase A, which is needed to break down GM2 ganglioside, a substance that otherwise builds up in the brain and spinal cord. Tay-Sachs most commonly occurs in young children, and some of the symptoms that appear can be categorized as childhood dementia.
Menkes disease affects how levels of copper are controlled within the body. Copper is essential for the function of lots of systems and organs, but only a tiny amount is required. Mutation of the ATP7A gene in people with Menkes disease means that copper is not distributed correctly, with too much in some tissues and not enough in others. It mostly affects male children and is nicknamed “kinky hair disease”, due to the coarse, curly hair pattern these children tend to have.
This is just a snapshot of the dozens of genetic diseases that are known to cause dementia in children, and research will probably uncover more in years to come.
What are the symptoms of childhood dementia?
The causes might be quite different, but many of the symptoms of childhood dementia are the same ones we would recognize from adult dementia.
Children can experience memory loss, confusion, and difficulties with learning, communicating, and concentrating. The symptoms can start at different ages, depending on the specific genetic cause, but in all cases they are progressive. Over time, affected children start to lose skills they’ve learned, such as reading, walking, and playing. Eventually, the brain is unable to keep the body functioning properly.
Speaking to the Childhood Dementia Initiative for their white paper, one mother described her daughter’s worsening symptoms:
“We’ve had to watch our beautiful 7-year-old daughter lose the ability to run, to walk, to dance. She’s lost cognitive skills so she can no longer count or sing her favourite nursery rhymes. She’s lost the ability to speak. She’s going blind, she’s finding it harder and harder to recognise family and friends. We also have the challenges of her behaviour and personality changes that all come along with childhood dementia.”
As well as the cognitive symptoms, children can also experience a raft of other effects, including seizures, and problems with their bones and joints.
Because some of the early symptoms can be hard to distinguish from other disorders, it can take some time for children to receive an accurate diagnosis.
Can childhood dementia be treated or cured?
Of the over 70 disorders that are known to cause childhood dementia, fewer than 5 percent have any kind of available treatment. For the majority of children, there is currently no hope of a cure for their disease.
The Childhood Dementia Initiative estimates that there are 48,300 premature deaths from the condition annually across the globe. Overall collective life expectancy is 28 years, but in reality, three-quarters of children with dementia will be expected to die by age 18.
Campaigners are working to raise awareness of childhood dementia, which currently remains unrecognized as a standalone disease; this is despite the fact that in Australia, where the Childhood Dementia Initiative is based, its mortality rate is comparable to that of pediatric cancer.
“The figures show that childhood dementia carries a significant burden and needs are overwhelmingly unmet,” CEO Megan Donnell wrote in the white paper. “Children […] are relying on us to build greater awareness of childhood dementia and critically, the research and collaborations that will lead to the development of effective treatments that will save them from harrowing physical and mental decline.”
But, there is some cause for hope. For a small number of the conditions that cause childhood dementia, treatments are available, and notable recent advances have produced promising results.
What does the future hold?
Earlier this year, scientists from the University of Manchester in the UK reported the results of an early trial of a new gene therapy for Sanfilippo disease.
Sanfilippo disease, also known as Sanfilippo syndrome or MPS III, is the most common subtype of mucopolysaccharidosis. It’s caused by a recessive gene; if both parents are carriers, there is a one in four chance that their child will be born with the disease.
Symptoms typically appear after the age of one and include many of the hallmarks of childhood dementia that we've discussed, as well as joint stiffness, difficulty walking, diarrhea, and some facial differences. Like most causes of childhood dementia, there is currently no approved treatment for Sanfilippo disease, so the new gene therapy trial is especially welcome.
The study included children aged between six and 24 months, which the researchers caution is before the worst symptoms of Sanfilippo disease are normally seen. They were given the experimental treatment, called OTL-201, and will continue to be followed up for a minimum of three years.
The preliminary results were revealed at a conference in February 2023. The treatment was found to be safe and well-tolerated, and four out of five children taking part have gained cognitive skills that would be expected in healthy children of the same age.
“These are encouraging results for children living with [Sanfilippo disease] and their families, who currently have no effective treatment options,” said chief investigator Professor Robert Wynn in a statement.
“Importantly, the safety of the therapy is looking very good in these patients so far,” added Professor Brian Bigger, who performed the preclinical work leading up to the trial.
The researchers celebrated these positive early results but highlighted that there is still much work to be done. And, as we have seen, Sanfilippo disease is just one of a myriad causes of childhood dementia. In many ways, research into these conditions is still in its infancy; but, for the thousands of children affected by childhood dementia, more awareness and better treatments cannot come soon enough.
As Professor Bigger said of the OTL-201 trial: “We have been hopeful this therapy will be transformative for patients – and these early results are very positive – but there’s still a long way to go.”
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