We review research findings on the oldest old that demonstrate that the fourth age entails a level of biocultural incompleteness, vulnerability and unpredictability that is distinct from the positive views of the third age (young old). The oldest old are at the limits of their functional capacity and science and social policy are constrained in terms of intervention. New theoretical and practical endeavors are required to deal with the challenges of increased numbers of the oldest old and the associated prevalence of frailty and forms of psychological mortality (e.g., loss of identity, psychological autonomy and a sense of control). Investigation of the fourth age is a new and challenging interdisciplinary research territory. Future study and discussion should focus on the critical question of whether the continuing major investments into extending the life span into the fourth age actually reduce the opportunities of an increasing number of people to live and die in dignity.

Subjective well-being is thought to remain relatively stable into old age despite health-related losses. Age and functional health constraints were examined as predictors of individual differences and intraindividual change in subjective well-being, as indicated by positive and negative affect, using cross-sectional (N = 516) and longitudinal (N = 203) samples from the Berlin Aging Study (age range 70-103 years). In cross-sectional and longitudinal analyses, age and functional health constraints were negatively related to positive affect but unrelated to negative affect. Cross-sectionally, controlling for functional health constraints reversed the direction of the relationship between age and positive affect and produced a negative association between age and negative affect. Findings suggest two qualifications to the average stability of overall subjective well-being: Only some dimensions of subjective well-being remain stable, while others decline; age per se is not a cause of decline in subjective well-being but health constraints are.

Theories of social relations suggest that individuals' personal networks reflect multiple aspects of relationships, and that different constellations are more or less supportive of well-being. Using data from the Berlin Aging Study (N = 516; age, M = 85 years), we derived network types that reflect information about structure, function, and quality, and we examined their association with well-being. A cluster analysis revealed six network types: diverse-supported, family focused, friend focused-supported, friend focused-unsupported, restricted-nonfriends-unsatisfied, and restricted-nonfamily-unsupported. Well-being was predicted differentially by the six types. Although the oldest-old individuals (85 years of age or older) were overrepresented in the friend-focused-supported and restricted types, age did not moderate the association of types with well-being. A holistic consideration of structure, function, and quality of social networks in old age offers unique insights.

Adult age differences in cognitive plasticity have been studied less often in working memory than in episodic memory. The authors investigated the effects of extensive working memory practice on performance improvement, transfer, and short-term maintenance of practice gains and transfer effects. Adults age 20 -30 years and 70 -80 years practiced a spatial working memory task with 2 levels of processing demands across 45 days for about 15 min per day. In both age groups and relative to age-matched, no-contact control groups, we found (a) substantial performance gains on the practiced task, (b) near transfer to a more demanding spatial n-back task and to numerical n-back tasks, and (c) 3-month maintenance of practice gains and near transfer effects, with decrements relative to postpractice performance among older but not younger adults. No evidence was found for far transfer to complex span tasks. The authors discuss neuronal mechanisms underlying adult age differences and similarities in patterns of plasticity and conclude that the potential of deliberate working memory practice as a tool for improving cognition in old age merits further exploration.