Psychology › Development & attachment › Lifespan development
Aging: what declines and what doesn't
· Concept
Well replicatedStrong, repeated evidence.
Getting older brings slower speed and recall but steady or growing knowledge, judgment and emotional balance.
See it on the Psychology map →What it says
Abilities age differently. Processing speed, working memory and quick recall start slipping in early adulthood. Vocabulary, general knowledge and expertise, called crystallized intelligence, hold up or grow into the 60s and 70s. Experience compensates: older typists look further ahead in the text to keep their speed. Emotional life often improves, with fewer negative feelings. Differences between people widen with age, shaped by health, education, hearing, exercise and social ties.
Why it matters
It matters for work, money and family. A 2009 study of loan and credit-card data found financial mistakes were fewest around age 53, then rose, so planning ahead protects older decision-makers.
Think of it like
Speed depreciates like building systems; knowledge accrues like equity.
The evidence
Status: well replicated. Cross-sectional and long-term studies, such as Timothy Salthouse's work and the Seattle Longitudinal Study, plus real-world data like Agarwal, Laibson and colleagues' 2009 analysis of financial errors by age.
Open questions
Why people age so differently, and why some 'SuperAgers' in their 80s keep the memory of people decades younger; Northwestern studies find thicker cortex in some regions.
Connections (6)
▸Brain-training games claimed to slow Aging: what declines and what doesn'tWeak or failed to replicate
The connection
Companies such as Lumosity marketed puzzle games as a way to keep the aging brain sharp and stave off decline. Players do get better at the games themselves, but large studies find little transfer to everyday memory, thinking or independence. One older trial, ACTIVE, reported possible long-term benefits from speed training, which remain debated.
Who showed it and when
Lumosity launched in 2007; in 2016 its maker paid $2 million to settle Federal Trade Commission charges of deceptive claims. ACTIVE enrolled about 2,800 older Americans from 1998.
How solid is it?
A 2014 consensus statement from about 70 scientists, organized by the Stanford Center on Longevity, and a 2016 review by Daniel Simons and colleagues found no convincing evidence of broad benefits.
Open questions
Whether ACTIVE's speed-training results, including fewer car crashes and possibly lower dementia rates a decade later, are real or chance findings among many outcomes.
▸Neuroplasticity: the brain rewires with use persists into Aging: what declines and what doesn'tWell replicated
The connection
The brain keeps rewiring through old age, though more slowly. Older adults can learn new skills, such as juggling, a language or a new route, and scans show matching changes in gray matter. Plasticity is why exercise, hearing aids and new learning can help aging brains, and why recovery after a stroke is possible at any age.
Who showed it and when
Arne May's group in Germany showed in 2008 that 60-year-olds learning to juggle grew gray matter; Fred Gage's team reported new neurons in adult human brains in 1998.
The evidence
Brain-scan training studies, plus a 2011 trial in which a year of walking enlarged older adults' hippocampus by about 2%, offsetting one to two years of age-related shrinkage.
Open questions
Whether adult humans make meaningful numbers of new neurons; studies published in 2018 disagree sharply, possibly because of how brain tissue was handled.
▸Aging: what declines and what doesn't is the last chapter of Lifespan developmentWell replicated
The connection
Late adulthood is development too, with gains as well as losses. Processing speed and recall slow, but knowledge, vocabulary and emotional balance often hold or improve. Laura Carstensen's research finds older adults focus on fewer, more meaningful relationships and report fewer negative emotions. With longer lives, this chapter can now last 30 years or more.
Who showed it and when
Paul Baltes in Berlin argued from the 1980s that development continues through old age; Stanford's Laura Carstensen developed socioemotional selectivity theory in the 1990s.
The evidence
Long-term studies such as the Berlin Aging Study (from 1990) and the Seattle Longitudinal Study document gains alongside losses in the same people.
Open questions
Whether added years of life are mostly healthy years or years with illness; data from different countries and periods disagree.
▸Fluid vs crystallized intelligence explains which skills fade in Aging: what declines and what doesn'tWell replicated
The connection
The split explains the mixed picture of aging. Fluid skills, such as quick reasoning on new problems, processing speed and juggling information, decline gradually from early adulthood. Crystallized skills, such as vocabulary, general knowledge and expertise, hold steady or grow into the 60s or 70s, so older adults often do as well in familiar domains.
Who showed it and when
Cattell and John Horn's work in the 1960s; K. Warner Schaie's Seattle Longitudinal Study, begun in 1956; Timothy Salthouse's large age comparisons since the 1990s.
The evidence
Both snapshot and long-term studies show the pattern, and a 2009 study of financial mistakes found them fewest around age 53.
Open questions
When declines start is disputed: snapshot studies suggest the 20s or 30s, while long-term studies tracking the same people suggest after 60.
▸Personality changes with age (maturity principle) continue into Aging: what declines and what doesn'tWell replicated
The connection
Personality keeps changing past midlife. People tend to grow more agreeable and emotionally stable into their 60s and 70s, while openness, sociability and later conscientiousness dip in very old age. Older adults also focus more on positive experiences. A sudden, marked late-life personality shift, however, can be an early sign of brain disease.
Who showed it and when
Long-term studies in the US, Germany, Australia and elsewhere; a 2020 coordinated analysis by Eileen Graham and colleagues pooled 16 longitudinal samples.
The evidence
Multiple panel studies show the late-life pattern, though measuring very old adults is harder because frail participants drop out.
Open questions
Whether late-life declines reflect normal aging, illness or retirement's changed demands, and how best to tell normal change from early dementia.
▸Dementia and Alzheimer's disease are not a normal part of Aging: what declines and what doesn'tWell replicated
The connection
Age is the biggest risk factor, but dementia is disease, not normal aging. Normal aging means slower recall, like misplacing keys or reaching for names. Dementia means losing the ability to manage daily life: getting lost on familiar routes, struggling with bills, repeating questions. About a third of Americans over 85 have Alzheimer's; most do not.
Who showed it and when
The distinction hardened after neurologist Robert Katzman's 1976 editorial argued that much 'senility' was Alzheimer's disease, reshaping research and funding.
The evidence
Long-term studies show many people reach their 90s and 100s mentally intact, and autopsies tie dementia to specific diseases rather than age itself.
Open questions
Whether everyone would eventually develop dementia if they lived long enough; rates keep rising into the late 90s, and the answer is unknown.