What Is the Life Expectancy of Level 3 Autism?

Understanding Level 3 Autism and Its Challenges

Let’s start with the basics. Level 3 autism, as defined in the DSM-5, refers to "requiring very substantial support." People diagnosed at this level often have limited verbal communication, significant difficulties with daily functioning, and may show severe sensory sensitivities or repetitive behaviors.

This isn’t just “being quirky” or “having social anxiety.” Level 3 is complex — and yes, life-altering.

Why is life expectancy even a question?

Well, honestly? Because studies have shown that autistic people — especially those with higher support needs — often face increased health risks. And that sucks to admit, but we’ve gotta face it to change it.

What the research actually says

The numbers aren’t great (but context matters)

Several studies have examined autism and life expectancy. A major 2017 Swedish study published in The British Journal of Psychiatry found that autistic individuals had a life expectancy around 16 years shorter than neurotypical people.

For individuals with Level 3 autism, the gap can be even wider — some estimates place average life expectancy around 36–54 years, depending on care, comorbid conditions, and access to support.

Shocking? Yeah. But here’s the thing: it’s not autism itself that shortens life. It’s everything around it.

Factors that affect life expectancy in Level 3 autism

1. Co-occurring medical conditions

People with Level 3 autism often have other diagnoses too — epilepsy, gastrointestinal issues, sleep disorders, etc.
Epilepsy alone, which affects about 20–30% of autistic individuals with high support needs, is a major contributor to early mortality.

2. Communication barriers

Trouble expressing pain or discomfort can delay diagnosis of serious health issues. If someone can’t say “my stomach hurts” or “I feel dizzy,” it might go unnoticed until it's a crisis.

3. Mental health & safety concerns

People with severe autism are at higher risk of accidental injury, self-harm, and in some cases, neglect — especially in underfunded or overwhelmed care systems.

I once volunteered in a residential program where a nonverbal young adult had a severe allergic reaction. Staff noticed only because his pacing increased dramatically. That kind of situation? It can be deadly if missed.

4. Social and systemic neglect

Let's be real — the healthcare system isn’t always autism-friendly. Misdiagnosis, dismissal of symptoms, or lack of adapted services make everything harder.

But here’s the nuance — it’s not a fixed sentence

Yes, the stats are scary. But stats don’t equal fate.

With proper medical care, emotional support, stable housing, and daily assistance, people with Level 3 autism can and do live into their 60s or longer. There are even examples of individuals living into their 70s, though that’s not (yet) the norm.

Quality of care makes a HUGE difference

Families who advocate fiercely, caregivers who are trained in autism-specific needs, and communities that include rather than isolate — these all change the game. Drastically.

Improving life expectancy: what actually helps?

• Regular medical checkups with doctors who understand autism

• Consistent routines to reduce stress and anxiety

• Occupational therapy to support daily function

• Nutrition and physical activity, adapted to sensory needs

• Emotional regulation tools, especially non-verbal ones like visual cards or AAC devices

• And maybe most importantly: respect, dignity, and inclusion

Final thoughts: it’s not just about the years — it’s the life lived

So, what is the life expectancy of someone with Level 3 autism?
It depends. On healthcare. On environment. On people who show up and care.

But more than that — the question shouldn't be just how long they live. It should also be how well. Because every life, regardless of support level, deserves to be full, respected, and heard.

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How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).

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Average Height to Weight for Teenage Boys - 13 to 20 Years

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Generally speaking, the average height for 15 year olds girls is 62.9 inches (or 159.7 cm). On the other hand, teen boys at the age of 15 have a much higher average height, which is 67.0 inches (or 170.1 cm).

Can you grow between 16 and 18?

Most girls stop growing taller by age 14 or 15. However, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18. Note that some kids will stop growing earlier and others may keep growing a year or two more.

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Even with a healthy diet, most people's height won't increase after age 18 to 20. The graph below shows the rate of growth from birth to age 20. As you can see, the growth lines fall to zero between ages 18 and 20 ( 7 , 8 ). The reason why your height stops increasing is your bones, specifically your growth plates.