Aging in the context of "Social environment"

Developmental psychology is the scientific study of how and why humans grow, change, and adapt across the course of their lives. Originally concerned with infants and children, the field has expanded to include adolescence, adult development, aging, and the entire lifespan. Developmental psychologists aim to explain how thinking, feeling, and behaviors change throughout life. This field examines change across three major dimensions, which are physical development, cognitive development, and social emotional development. Within these three dimensions are a broad range of topics including motor skills, executive functions, moral understanding, language acquisition, social change, personality, emotional development, self-concept, and identity formation.

Developmental psychology explores the influence of both nature and nurture on human development, as well as the processes of change that occur across different contexts over time. Many researchers are interested in the interactions among personal characteristics, the individual's behavior, and environmental factors, including the social context and the built environment. Ongoing debates in regards to developmental psychology include biological essentialism vs. neuroplasticity and stages of development vs. dynamic systems of development. While research in developmental psychology has certain limitations, ongoing studies aim to understand how life stage transitions and biological factors influence human behavior and development.

Death is the end of life, the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose shortly after death. Some organisms, such as Turritopsis dohrnii, are biologically immortal; however, they can still die from means other than aging. Death is generally applied to whole organisms; the equivalent for individual components of an organism, such as cells or tissues, is necrosis. Something that is not considered an organism can be physically destroyed but is not said to die, as it is not considered alive in the first place.

As of the early 21st century, 56 million people die per year. The most common reason is aging, followed by cardiovascular disease, which is a disease that affects the heart or blood vessels. As of 2022, an estimated total of almost 110 billion humans have died, or roughly 94% of all humans to have ever lived. A substudy of gerontology known as biogerontology seeks to eliminate death by natural aging in humans, often through the application of natural processes found in certain organisms. However, as humans do not have the means to apply this to themselves, they have to use other ways to reach the maximum lifespan for a human, often through lifestyle changes, such as calorie reduction, dieting, and exercise. The idea of lifespan extension is considered and studied as a way for people to live longer.

Old age is the range of ages for people nearing and surpassing life expectancy. People of old age are called old people, the elderly, elders, senior citizens, seniors, or older adults. Old age is not a definite biological stage: the chronological age denoted as "old age" varies culturally and historically. Some disciplines and domains focus on the aging and the aged, such as the organic processes of aging (senescence), medical studies of the aging process (gerontology), diseases that afflict older adults (geriatrics), technology to support the aging society (gerontechnology), and leisure and sport activities adapted to older people (such as senior sport).

Old people often have limited regenerative abilities and are more susceptible to illness and injury than younger adults. They face social problems related to retirement, loneliness, and ageism.

Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform everyday activities. This typically involves problems with memory, thinking, behavior, and motor control. Aside from memory impairment and a disruption in thought patterns, the most common symptoms of dementia include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia is a life-limiting condition, having a significant effect on the individual, their caregivers, and their social relationships in general. A diagnosis of dementia requires the observation of a change from a person's usual mental functioning and a greater cognitive decline than might be caused by the normal aging process.

Several diseases and injuries to the brain, such as a stroke, can give rise to dementia. However, the most common cause is Alzheimer's disease, a neurodegenerative disorder. Dementia is a neurocognitive disorder with varying degrees of severity (mild to major) and many forms or subtypes. Dementia is an acquired brain syndrome, marked by a decline in cognitive function, and is contrasted with neurodevelopmental disorders. It has also been described as a spectrum of disorders with subtypes of dementia based on which known disorder caused its development, such as Parkinson's disease for Parkinson's disease dementia, Huntington's disease for Huntington's disease dementia, vascular disease for vascular dementia, HIV infection causing HIV dementia, frontotemporal lobar degeneration for frontotemporal dementia, Lewy body disease for dementia with Lewy bodies, and prion diseases. Subtypes of neurodegenerative dementias may also be based on the underlying pathology of misfolded proteins, such as synucleinopathies and tauopathies. The coexistence of more than one type of dementia is known as mixed dementia.

Geriatrics, or geriatric medicine, is a medical specialty focused on addressing the unique health needs of older adults. The term geriatrics originates from the Greek γέρων geron meaning "old man", and ιατρός iatros meaning "healer". It aims to promote health by preventing, diagnosing and treating disease in older adults. Older adults may be healthy, but they're more likely to have chronic health concerns and require more medical care. There is no defined age at which patients may be under the care of a geriatrician, or geriatric physician, a physician who specializes in the care of older people. Rather, this decision is guided by individual patient needs and the caregiving structures available to them. This care may benefit those who are managing multiple chronic conditions or experiencing significant age-related complications that threaten quality of daily life. Geriatric care may be indicated if caregiving responsibilities become increasingly stressful or medically complex for family and caregivers to manage independently.

There is a distinction between geriatrics and gerontology. Gerontology is the multidisciplinary study of the aging process, defined as the decline in organ function over time in the absence of injury, illness, environmental risks or behavioral risk factors. However, geriatrics is sometimes called medical gerontology.

Senescence (/ˌsɪˈnɛsəns/) or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle. However, the effects of senescence can be delayed. The 1934 discovery that calorie restriction can extend lifespans by 50% in rats, the existence of species having negligible senescence, and the existence of potentially immortal organisms such as members of the genus Hydra have motivated research into delaying senescence and thus age-related diseases. Rare human mutations can cause accelerated aging diseases.

Environmental factors may affect aging – for example, overexposure to ultraviolet radiation accelerates skin aging. Different parts of the body may age at different rates and distinctly, including the brain, the cardiovascular system, and muscle. Similarly, functions may distinctly decline with aging, including movement control and memory. Two organisms of the same species can also age at different rates, making biological aging and chronological aging distinct concepts.

Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", "immortalists", or "longevists" (those who wish to achieve longer lives themselves), postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.

The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry that promotes the use of hormones as a treatment for consumers to slow or reverse the aging process in the US market generated about $50 billion of revenue a year in 2009. The use of such hormone products has not been proven to be effective or safe. Similarly, a variety of apps make claims to assist in extending the life of their users, or predicting their lifespans.