New research suggests that human ageing is not a gradual process but happens in two accelerated bursts, around the ages of 44 and 60. The findings, published by US scientists, could explain sudden spikes in health issues such as musculoskeletal problems and cardiovascular disease at certain ages.
The study, led by Prof Michael Snyder at Stanford University, tracked 108 volunteers aged 25 to 75 over several years. Researchers analysed 135,000 different molecules and microbes from blood, stool, skin, oral and nasal samples. They found that most molecules did not change gradually but showed two major waves of transformation.
The mid-40s spike was initially thought to be linked to perimenopause in women, but similar changes were observed in men. Dr Xiaotao Shen, first author of the study, said this suggests other significant factors are at play. The first wave involved molecules related to cardiovascular disease and metabolism of caffeine, alcohol and lipids.
The second wave, around age 60, included changes in molecules linked to immune regulation, carbohydrate metabolism and kidney function. Molecules associated with skin and muscle ageing changed at both time points. The pattern aligns with evidence that risks for Alzheimer's and cardiovascular disease increase sharply after 60.
Some changes may be linked to lifestyle factors, such as increased alcohol consumption in the mid-40s. The authors suggest interventions like increasing exercise during periods of rapid muscle loss. “I’m a big believer that we should try to adjust our lifestyles while we’re still healthy,” Snyder said.
