Down syndrome natural history, complications and prognosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

3% of fetuses with Down’s syndrome diagnosed in utero at 16 weeks’ gestation would be lost spontaneously if termination of pregnancy was not performed. At birth, 50% of newborns with Down’s syndrome have one or more additional serious congenital abnormalities (in addition to intellectual disability). 96% without and 80% with heart defects survive the first year. At age 21 mean IQ is 42 (range 8–67) and mental age is 5 years (range 1–8 years). 11% develop Alzheimer’s disease by age 50 and 77% by age 70 (mean age of onset age 56). Common complication that may arise in patients suffering from Down syndrome include, congenital heart defects (ASD, VSD, PDA), hearing loss, diabetes, celiac disease, cataracts, endocarditis, atlantoaxial subluxation, hypo and hyperthyroidism, duodenal atresia, Hirschprung disease. Life expectancy is 50–55 years.

The natural history of Down syndrome consists of the following findings:

Inutero

• 3% of fetuses with Down’s syndrome diagnosed in utero at 16 weeks’ gestation would be lost spontaneously if termination of pregnancy was not performed; at 10 weeks’ gestation the figure is 43%

At birth

• 50% of live births with Down’s syndrome have one or more additional serious congenital abnormalities (in addition to intellectual disability)
• 46% have congenital heart defects

Infancy and early childhood

• 96% without and 80% with heart defects survive the first year
• 20% of live borns die before age 5; after age 5 survival to adulthood is likely
• More than 50 % of live borns survive to age 60

Adulthood

• At age 21 mean IQ is 42 (range 8–67) and mental age is 5 years (range 1–8 years)
• 11% develop Alzheimer’s disease by age 50 and 77% by age 70 (mean age of onset age 56)

Common complications that may develop in patients suffering from Down syndrome include the following:

• Airway blockage during sleep
• Compression injury of the spinal cord
• Endocarditis
• Cataracts
• Strabismus
• Frequent ear infections and increased risk of other infections
• Hearing loss
• Atrial septal defects
• Ventricular septal defects
• Patent ductus arteriosus
• Hypo and hyperthyroidism
• Diabetes
• Celiac disease
• Gastrointestinal blockage
• Atlantoaxial subluxation

These factors can contribute to a shorter life expectancy for people with Down syndrome. One study, carried out in the United States in 2002, showed an average lifespan of 49 years, with considerable variations between different ethnic and socio-economic groups. However, in recent decades, the life expectancy among persons with Down syndrome has increased significantly up from 25 years in 1980. The causes of death have also changed, with chronic neurodegenerative diseases becoming more common as the population ages. Most people with Down Syndrome who survive into their 40s and 50s begin to suffer from an Alzheimer’s disease-like dementia.

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