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A number of characteristic ageing symptoms are experienced by a majority or by a significant proportion of humans during their lifetimes.


 * Teenagers lose the young child's ability to hear high-frequency sounds above 20 kHz.
 * Wrinkles develop mainly due to photoageing, particularly affecting sun-exposed areas (face).
 * After peaking from the late teens to the late 20s, female fertility declines.
 * After age 30 the mass of human body is decreased until 70 years and then shows damping oscillations.
 * People over 35 years of age are at increasing risk for losing strength in the ciliary muscle of the eyes which leads to difficulty focusing on close objects, or presbyopia. Most people experience presbyopia by age 45–50. The cause is lens hardening by decreasing levels of alpha-crystallin, a process which may be sped up by higher temperatures.
 * Around age 50, hair turns grey. Pattern hair loss by the age of 50 affects about 30–50% of males and a quarter of females.
 * Menopause typically occurs between 44 and 58 years of age.
 * In the 60–64 age cohort, the incidence of osteoarthritis rises to 53%. Only 20% however report disabling osteoarthritis at this age.
 * Almost half of people older than 75 have hearing loss (presbycusis) inhibiting spoken communication. Many vertebrates such as fish, birds and amphibians do not develop presbycusis in old age as they are able to regenerate their cochlear sensory cells, whereas mammals including humans have genetically lost this ability.
 * By age 80, more than half of all Americans either have a cataract or have had cataract surgery.
 * Frailty, a syndrome of decreased strength, physical activity, physical performance and energy, affects 25% of those over 85. Muscles have a reduced capacity of responding to exercise or injury and loss of muscle mass and strength (sarcopenia) is common. Maximum oxygen utilization and maximum heart rate decline. Hand strength and mobility decrease.
 * Atherosclerosis is classified as an ageing disease. It leads to cardiovascular disease (for example stroke and heart attack) which globally is the most common cause of death. Vessel ageing causes vascular remodeling and loss of arterial elasticity and as a result causes the stiffness of the vasculature.
 * Recent evidence suggests that age-related risk of death plateaus after age 105. The maximum human lifespan is suggested to be 115 years. The oldest reliably recorded human was Jeanne Calment who died in 1997 at 122.

Dementia becomes more common with age. About 3% of people between the ages of 65 and 74, 19% between 75 and 84, and nearly half of those over 85 years of age have dementia. The spectrum ranges from mild cognitive impairment to the neurodegenerative diseases of Alzheimer's disease, cerebrovascular disease, Parkinson's disease and Lou Gehrig's disease. Furthermore, many types of memory decline with ageing, but not semantic memory or general knowledge such as vocabulary definitions, which typically increases or remains steady until late adulthood (see Ageing brain). Intelligence declines with age, though the rate varies depending on the type and may in fact remain steady throughout most of the lifespan, dropping suddenly only as people near the end of their lives. Individual variations in the rate of cognitive decline may therefore be explained in terms of people having different lengths of life. There are changes to the brain: after 20 years of age there is a 10% reduction each decade in the total length of the brain's myelinated axons.

Age can result in visual impairment, whereby non-verbal communication is reduced, which can lead to isolation and possible depression. Older adults, however, may not experience depression as much as younger adults, and were paradoxically found to have improved mood despite declining physical health. Macular degeneration causes vision loss and increases with age, affecting nearly 12% of those above the age of 80. This degeneration is caused by systemic changes in the circulation of waste products and by growth of abnormal vessels around the retina. Other visual diseases that often appear with age would be cataracts and glaucoma. A cataract occurs when the lens of the eye becomes cloudy making vision blurry and eventually causing blindness if untreated. They develop over time and are seen most often with those that are older. Cataracts can be treated through surgery. Glaucoma is another common visual disease that appears in older adults. Glaucoma is caused by damage to the optic nerve causing vision loss. Glaucoma usually develops over time but there are variations to glaucoma, and some have sudden onset. There are a few procedures for glaucoma but there is no cure or fix for the damage once it has happened. Prevention is the best measure in the case of glaucoma.

A distinction can be made between "proximal ageing" (age-based effects that come about because of factors in the recent past) and "distal ageing" (age-based differences that can be traced to a cause in a person's early life, such as childhood poliomyelitis).

Ageing is among the greatest known risk factors for most human diseases. Of the roughly 150,000 people who die each day across the globe, about two-thirds—100,000 per day—die from age-related causes. In industrialized nations, the proportion is higher, reaching 90%.