Lung Function: Evolution from Childhood to Early Adulthood Decline

Emerging evidence in pulmonary medicine is reshaping our understanding of lung development and aging. For decades, it was widely accepted that lung function plateaus after peaking in late adolescence or early adulthood, maintaining stability into midlife before beginning a gradual decline. However, recent longitudinal data challenge this notion, indicating that the decline in lung capacity may begin as early as the early twenties. This shift has significant implications for how clinicians assess, monitor, and manage respiratory health across the lifespan.

A landmark study published in the New England Journal of Medicine followed participants from childhood into their mid-twenties and found that individuals with persistent asthma exhibited impaired lung growth and experienced an early decline in forced expiratory volume in one second (FEV₁). Some participants had spirometric patterns suggestive of early chronic obstructive pulmonary disease (COPD) by young adulthood, highlighting how early-life respiratory health can influence long-term outcomes.

Complementing these findings, a systematic review published in BMJ Open examined over 31,000 adults without known respiratory disease and found that FEV₁ begins to decline in early adulthood. Annual declines ranged from 17.7 to 46.4 mL, depending on demographic and clinical variables. While men experienced faster absolute declines in FEV₁, relative changes were similar across genders, reinforcing the importance of gender-specific evaluations when interpreting lung function metrics.

These insights challenge traditional models of lung physiology that presumed a stable plateau in young adulthood. Instead, they support a more dynamic view: lung function peaks in late adolescence or early adulthood, followed swiftly by a gradual but measurable decline. This revised trajectory emphasizes the need for earlier interventions and more vigilant surveillance, especially among individuals with predisposing factors such as asthma, smoking exposure, or occupational hazards.

Clinicians are increasingly encouraged to adopt a more proactive stance by initiating respiratory assessments earlier in life and educating patients about lung health preservation. Interventions may include lifestyle modifications, minimizing exposure to respiratory irritants, and preventive pharmacological strategies where appropriate. Recognizing that the window for peak lung health may close earlier than previously believed allows healthcare providers to better tailor preventive efforts to sustain pulmonary function over time.

As our understanding of lung aging evolves, so too must our clinical strategies. Embracing a life-course perspective that accounts for early decline may enhance long-term respiratory outcomes and offer patients a clearer path to preserving lung vitality well into later decades.