Ageing is arguably the single most important risk factor for many of the leading causes of death and disability in the developed world. As humans age, molecular and cellular changes accumulate that substantially increase susceptibility to diseases like cancer, heart disease, diabetes, osteoporosis, and neurodegenerative diseases. Understanding how ageing drives disease is key to developing preventive and therapeutic strategies.
The incidence of common cancers including lung, breast, colon, prostate, and skin cancer skyrockets in older populations compared to younger demographics. Ageing causes genomic instability from accumulated DNA damage, epigenetic alterations, and telomere shortening that allow malignant transformation. Cellular senescence and impaired apoptosis further enable cancerous cells to proliferate. Adults over age 65 have a 10-20 fold greater risk of developing cancer compared to young adults.
For example, colorectal cancer is over 90% more likely to occur in 60-79-year-olds versus 40-59-year-olds. Accumulated mutations in oncogenes like KRAS and tumour suppressor genes like TP53 allow colon cells to become cancerous. Cellular senescence and chronic inflammation promote an environment ripe for cancer growth.
Ageing drastically increases the risk of cardiovascular diseases like coronary artery disease, heart failure, atrial fibrillation, and stroke. Ageing blood vessels stiffen and plaques accumulate, which can lead to heart attacks and strokes. One study found ageing accounted for a 20-fold increase in cardiovascular death risk from age 35 to 85. Lifestyle changes can reduce some age-related cardiovascular changes.
Alzheimer’s, Parkinson’s, and other neurodegenerative diseases become exponentially more common with advanced age. Ageing brain cells accumulate damaged proteins, have altered intercellular communication, and reduced regenerative capacity. For example, ageing is the strongest risk factor for Alzheimer’s disease, with incidence doubling every 5 years after age 65. Delaying or reversing aspects of ageing may help prevent disease initiation.
Progressive bone loss occurs with ageing, dramatically increasing fracture risk in older adults. Bone regeneration slows as stem cells age. Women are especially at risk due to accelerated bone loss after menopause. Exercise and nutrition can help maintain bone health during ageing.
Both type 1 and type 2 diabetes risk increases substantially with ageing. Pancreatic cell function declines over time, and ageing also promotes insulin resistance in tissues like fat, liver, and muscle. One study found individuals over age 60 have triple the risk of developing diabetes compared to those ages 45-54. Weight control and activity can offset some ageing effects of diabetes.
In conclusion, the ageing risk factor underlies the exponential increase in disease incidence seen with age. Therapies targeting root causes of ageing hold promise to delay disease and promote healthy longevity.