When you hear the word “dementia,” you may think of older adults. The risk for dementia increases with age, but it can occasionally affect younger people. In very rare cases, children and teenagers can experience the condition.

Read on to find out how symptoms of dementia, including memory loss, can affect teens.

What Is Dementia?

Dementia isn’t a single disease — it’s a general term for symptoms that affect memory, thinking, and daily functioning. These symptoms can range from mild to severe and get worse over time. Some of the most common kinds of dementia include:

• Alzheimer’s disease
• Frontotemporal dementia
• Lewy body dementia (dementia with Lewy bodies)
• Vascular dementia
• Mixed dementia

The risk of developing these types of dementia increases later in life, but in rare cases, symptoms of dementia may appear in children and teens.

Childhood Dementia and Teenagers

Childhood dementia refers to a group of inherited disorders that damage brain cells and cause the loss of skills such as learning, memory, and movement. These conditions usually begin early in childhood, though some children may not show symptoms until their early teenage years.

Conditions that cause childhood dementia include:

• Batten disease (neuronal ceroid lipofuscinosis)
• Sanfilippo syndrome (mucopolysaccharidosis type 3)
• Niemann-Pick disease type C
• Mitochondrial disorders

Just like Alzheimer’s, these conditions damage nerve cells in the brain over time. As brain cells die, children with these conditions gradually lose their ability to communicate, problem solve, and perform basic functions. Unfortunately, these rare diseases often shorten life expectancy, and most children live only into their teenage years.

Early-Onset Dementia vs. Childhood Dementia

Sometimes, people confuse early-onset dementia or young-onset dementia with childhood dementia, but these conditions are distinct. Early-onset dementias affect adults under the age of 65, most often beginning in a person’s 30s, 40s, or 50s. These types of dementia rarely occur in teens.

Your risk for early-onset dementia may be increased by damage to the brain, including having a history of a stroke, traumatic brain injury, or heavy alcohol use. One specific population at risk is people with Down syndrome, who usually have changes in the brain by age 40 that lead to Alzheimer’s.

The risk may also be increased with genetic syndromes, such as familial Alzheimer’s disease (FAD). If you have a history of early-onset Alzheimer’s disease in the family, it is worth discussing the possible benefits of genetic testing with your doctor.

It’s nearly unheard of for a teen to develop an aging-related dementia, although cases of aging-related dementia have been noted in young people. In 2023, one journal reported a case of probable Alzheimer’s in a 19-year-old from China. Generally, dementia that appears in the teenage years is nearly always caused by a genetic condition that began earlier in life.

Could Sudden Confusion in a Teen Be Dementia?

If a teen suddenly becomes confused, forgetful, or disoriented, dementia is almost never the cause. One major explanation could be delirium, also known as acute confusional state. Delirium is a sudden, reversible change in mental status caused by other health conditions. There are many root causes of delirium. In a teen, potential causes include things like intoxication, dehydration, prolonged hospitalization, fever, or infection.

Delirium is a serious medical condition that needs to be checked by a doctor right away. It can show up in three different ways:

• Hyperactive delirium may include hallucinations, rapid mood changes, and restlessness.
• Hypoactive delirium can look like sluggishness, drowsiness, or a dazed state.
• Mixed delirium includes symptoms of both other types.

Other reasons why a teen may be suddenly confused or have memory changes may include:

• Lack of sleep
• Anxiety or depression
• Head injury
• Seizures
• Drug or alcohol use
• Trauma
• Anesthesia

If your teen shows sudden confusion or memory problems, it’s important to see a doctor. They can find the cause and decide if treatment is needed.

When To See a Doctor

If you notice signs of dementia in your teen, talk to your doctor. If they’re concerned about childhood dementia, they may refer you to a neurologist (a doctor who’s an expert in brain and nerve disorders) or a geneticist (a doctor who diagnoses and treats inherited diseases).

If you’ve been diagnosed with early-onset dementia, ask your doctor about genetic counselling and testing for other members of your family, including your teens.

Join the Conversation

On myALZteam, people share their experiences with Alzheimer’s, get advice, and find support from others who understand.

Has anyone in your family talked with a doctor about genetic risks for dementia? Let others know in the comments below.

References

1. What Is Dementia? Symptoms, Types, and Diagnosis — National Institute on Aging
2. What Causes Young-Onset Dementia? — Alzheimer’s Society
3. What Is Childhood Dementia? — Childhood Dementia Initiative
4. A 19-Year-Old Adolescent With Probable Alzheimer's Disease — Journal of Alzheimer’s Disease
5. Delirium in Children and Adolescents — American Academy of Child and Adolescent Psychiatry
6. Delirium — Nationwide Children’s Hospital
7. What Causes Memory Problems in Children? — Think Neurology for Kids