“Childhood Alzheimer’s” is not an actual medical condition. It is a term that some use to describe certain symptoms that resemble dementia in children.

Niemann-Pick disease type C (NPC) and mucopolysaccharidosis type 3 (MPS 3), or Sanfilippo syndrome, are two conditions that cause symptoms in childhood that may seem similar to those of Alzheimer’s disease. Both conditions are lysosomal storage disorders.

Lysosomes are essential components of cells that act as the cell’s digestive system. They contain various enzymes that break down proteins, carbohydrates, and lipids. If they do not work properly, the body cannot transport cellular sugars and fats, such as cholesterol, from the cells.

In individuals with lysosomal storage disorders, nutrients accumulate inside the cells, causing them to fail and die. Over time, this damage to the nervous system causes symptoms that resemble those of Alzheimer’s disease.

Keep reading to learn more about NPC and MPS 3 that some people sometimes call childhood Alzheimer’s, including the causes and symptoms and the outlook for someone with either of the conditions.

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Mutations, or changes, to specific genes cause conditions in children that may resemble Alzheimer’s disease. The genes involved determine the type of the condition a person has.

NPC

In NPC, an individual inherits recessive, mutated NPC1 or NPC2 genes from each of their parents. These genes then create deformed NPC1 or NPC2 proteins. The body needs healthy NPC1 and NPC2 proteins to transport cholesterol and other lipids out of the cells’ lysosomes.

Cholesterol is essential for creating cell membranes, steroids, and vitamins. If cholesterol cannot leave the lysosome, it cannot create these critical components.

Additionally, cholesterol and other lipids can accumulate in the cell, which leads to abnormal function and eventually death of the cell.

MPS 3

There are four sybtypes of MPS 3. The cause of each subtype is an abnormality of a specific gene: the GNS, HGSNAT, NAGLU, and SGSH genes.

In individuals with MPS 3, the genes that typically code for a particular enzyme do not function properly. This leads to an accumulation of partially broken down sugar molecule called heparan sulfate in the cells.

When these sugars build up, they gradually affect healthy cellular function, leading to a decline in nervous system and organ function and eventually cell death.

The symptoms a person will experience depend on the condition they have. However, both NPC and MPS 3 are degenerative diseases, meaning their symptoms worsen over time.

NPC

If a child has NPC, they could have severe, life threatening symptoms at a young age. Conversely, those with mild symptoms may not receive a diagnosis until adulthood. However, symptoms commonly affect school-aged children.

A teacher may raise concerns over a child’s behavior, as they may have trouble learning and retaining new information. Children with NPC may also be clumsy and have difficulty moving their eyes up and down.

Moreover, children with NPC may experience a sudden episode of loss of muscle tone and can fall to the floor. Doctors term this gelastic cataplexy.

Adult individuals with NPC may have symptoms resembling dementia, such as:

  • inflexible thought patterns
  • poor judgment
  • lack of attention and insight
  • mental slowness
  • memory difficulties
  • learning problems

Other symptoms may include:

MPS 3

Children with MPS 3 may not have symptoms at birth, and they may start to show signs of the condition during early childhood.

These children may experience severe neurological symptoms, such as progressive dementia, seizures, and altered behavior.

Around 80–99% of people with MPS 3 have the following symptoms:

Other symptoms include deafness, loss of vision, and a head that is larger than usual and that has coarse facial features.

As the condition progresses, children with MPS 3 lose motor function, and most cannot walk by the age 10.

There is currently no cure for NPC or MPS 3. However, a medication called miglustat may help slow disease progression by limiting lipid production. Children must receive their diagnosis as early as possible for the medication to have an optimal effect.

Treatment and management of these conditions centers around improving an individual’s symptoms and quality of life.

Some management approaches focus on addressing the following symptoms:

  • Difficulty swallowing: If an individual has dysphagia, consuming liquid or soft solid food and working with a speech therapist can improve swallowing function. Doctors may advise a stomach tube to deliver food and medicine.
  • Seizures: Doctors can prescribe anti-seizure medication, central nervous system stimulants, or antidepressants.
  • Sleep disturbances: If a person has sleep apnea, they may need a continuous positive air pressure machine to keep the airways open as they sleep. Doctors may also prescribe melatonin or nocturnal sedatives.
  • Muscle weakness: Occupational and physical therapy focus on building muscle strength, and movement may help individuals improve their muscle function.

A team of healthcare professionals specializing in child care, brain disorders, eye problems, and digestive issues may work together to create a comprehensive plan to manage the child’s symptoms.

Both NPC and MPS 3 are rare conditions. For example, MPS 3 may affect 1 out of 70,000–100,000 births.

Additionally, each of these conditions involves recessive genes, meaning each parent must carry the same mutated gene. If a child receives one normal gene and one mutated gene, they will be carriers as well, but typically, they will not show symptoms.

If both parents have the mutated gene, the risk of passing it on to the child is 25% with each pregnancy. The likelihood of the child being a carrier of the gene like the parents is 50% with each pregnancy.

Moreover, a child has a 25% chance of receiving normal genes from both parents. Both male and female children have the same risk of inheritance.

If parents are close relatives, the risk that they both carry the same mutated gene is higher. This then increases the likelihood of any children inheriting a recessive genetic condition.

Both NPC and MPS 3 are progressive conditions that contribute to a decreased life span.

Children with NPC have a variable life span that depends on the onset of the condition. Their life expectancy ranges from several days to several decades.

Children with MPS 3 also have a varied life expectancy. Most individuals live into their teenage years, and some may reach their 30s.

Childhood Alzheimer’s is not an actual medical condition. It is a name some people use when referring to symptoms that affect children and that resemble symptoms of dementia.

Two conditions that cause such symptoms are NPC and MPS 3, or Sanfilippo syndrome, which are rare genetic disorders.

Children with either of these conditions may show various symptoms that affect their learning, motor skills, brain function, nervous system, sleep patterns, and appearance.

There is currently no cure for NPC or MPS 3, and both conditions lead to a shortened life span. Treatment focuses on improving a person’s symptoms and quality of life.