Does high altitude exposure affect developmental growth in children?

Impact of High Altitude on Child Development

High altitude exposure can significantly impair child development, with effects on growth, cognitive function, and cardiovascular health that may have long-term consequences for morbidity and mortality. Children exposed to high altitudes above 3000m are at risk for developmental delays, stunting, and cognitive impairments that require prompt relocation to lower altitudes for resolution.

Physiological Effects of High Altitude on Children

Growth and Physical Development

• Children living at high altitudes (>4000m) show evidence of stunting (28.3%) compared to lowland peers 1
• Growth patterns are altered with delayed body size development but accelerated lung volume growth as an adaptation to hypoxic stress 2
• Children of high socioeconomic status still demonstrate reduced growth at high altitude, though the effect is smaller than in populations with nutritional deficiencies 3

Cardiovascular and Pulmonary Effects

• Infants and young children exposed to moderate altitude (3109m) experience:
  • Increased respiratory rates (from 45 to 51.9 breaths/min)
  • Decreased end-tidal CO₂ (from 31 to 28 mmHg)
  • Reduced arterial oxygen saturation (from 95% to 91%)
  • Decreased cerebral tissue oxygenation (from 78% to 67%) 4
• Younger children appear more susceptible to cerebral tissue oxygen desaturation at altitude 4

Cognitive and Behavioral Development

• Even relatively low altitudes (2500m) can delay reaction time and impair motor function 5
• Children born at high altitude may develop subtle cognitive and behavioral deficits suggesting incomplete adaptation to hypoxia 5
• Extreme altitude exposure (>5000m) can result in more pronounced impairment that may persist after returning to lower altitudes 5

High Altitude-Related Conditions in Children

Symptomatic High-Altitude Pulmonary Hypertension (SHAPH)

• Most commonly affects infants and children, particularly those of Chinese Han ancestry who move from low to high altitude (>3000m) 6
• Presents with symptoms of congestive heart failure
• Physical findings include right ventricular hypertrophy, dilation, and pulmonary hypertension
• Mortality rates range from 4-15% 6
• Doppler studies show significantly higher pulmonary arterial pressures (67±7 mmHg) compared to controls (34±4 mmHg) 6

High-Altitude Pulmonary Edema (HAPE)

• Can affect children with equal sex distribution (unlike adults where it's more common in males) 6
• Risk factors include:
  • Rapid ascent to altitudes above 2500m
  • Previous history of HAPE
  • Congenital heart defects
  • Pulmonary vascular abnormalities
  • Viral illness 6

Prevention and Management

For Children Living at High Altitude

• Proper acclimatization is essential with gradual ascent (300-600m/day above 2500m) 7
• Include rest days for every 600-1200m gained in altitude 7
• For children with SHAPH, prompt relocation to lower altitude is the definitive therapy 6
• No randomized controlled trials exist for SHAPH treatment in children 6

For Children with Pre-existing Conditions

• Children with congenital heart defects, pulmonary vascular abnormalities, or Down syndrome have increased risk of pulmonary hypertension at high altitude 6
• Children with these conditions should avoid high altitude exposure or have careful medical supervision

Long-term Implications

• Exposure to high altitude during growth and development results in enlarged residual lung volume 2
• This developmental adaptation, combined with increased tissue capillarization and moderate increases in red blood cells, contributes to functional adaptation in Andean high-altitude natives 2
• However, these adaptations may be incomplete, as subtle cognitive and behavioral deficits persist in native populations born at altitude 5

Clinical Recommendations

1. For families planning to relocate to high altitude (>2500m):

   • Consider the developmental risks, especially for infants and young children
   • Ensure gradual ascent and proper acclimatization
   • Monitor for signs of SHAPH or HAPE

2. For children already living at high altitude with developmental concerns:

   • Consider relocation to lower altitude as the definitive intervention
   • Monitor growth parameters, cognitive development, and cardiopulmonary function
   • Be particularly vigilant with infants, who appear most susceptible to cerebral tissue oxygen desaturation 4

3. For children with pre-existing conditions:

   • Those with congenital heart defects, Down syndrome, or pulmonary vascular abnormalities should avoid high altitude exposure
   • If exposure is unavoidable, ensure close medical monitoring and have a low threshold for descent

The evidence clearly indicates that high altitude exposure during childhood can significantly impact development, with potential long-term consequences for health and function. While some adaptations occur, they may be insufficient to prevent developmental impairments in susceptible children.