Analysis Essay

Good news about the ageing brain

BMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d6288 (Published 17 October 2011) Cite this as: BMJ 2011;343:d6288
  1. Marcus Richards, programme leader1,
  2. Stephani L Hatch, lecturer in social epidemiology2
  1. 1MRC Unit for Lifelong Health and Ageing, London WC1B 5JU, UK
  2. 2Institute of Psychiatry, King’s College London
  1. Correspondence to: M Richards m.richards{at}nshd.mrc.ac.uk

Important cognitive skills decline with age, but we retain a considerable mental richness in later life, say Marcus Richards and Stephani Hatch

In 1968 Robert Butler, a gerontologist and the first director of the US National Institute on Aging coined the term “ageism,” highlighting negative stereotypes in later life that emphasise loss and limitation. Subsequently, US president George Bush’s declaration of the 1990s as the “decade of the brain” increased public awareness of Alzheimer’s disease. Perhaps an unintended consequence of these developments is that cognitive decline and dementia have become, for many of us, the most feared aspects of old age. Little wonder that when our ageing minds wander, when we forget a name or the reason we went upstairs, we sometimes worry that these are warnings of a more sinister process. We should guard against the opposite tendency, the shallow false positivity that ageing is just an attitude of mind; this denies the reality that cognitive decline can impair everyday function and quality of life and may indeed be an early sign of dementia for some. Yet despite the myth that “you can’t teach an old dog new tricks,”1 people continue to learn over the life course and continue to develop a rich set of cognitive skills. This is important given the substantial increases in life expectancy in recent years, the pace of which is expected to quicken around the world.2

Cognitive ageing is not all bad

First we must acknowledge that cognitive ageing is not a simple or single entity. The evidence leaves no doubt that the intentional recall of detailed information bound to time and place is sensitive to age related decline.3 So is the kind of information processing necessary for complex multitasking. Yet memory for more abstract information, such as general knowledge or the meaning of words, is relatively well preserved and may actually improve as we age.4 Older people may be less able to remember specific details in a passage of text than younger people but are as good or better at understanding its gist5—important for competence in communication, if vulnerable to distortion. Or turning to everyday practical tasks that draw on cognitive skills, such as driving or adhering to drug treatment, these tend to be preserved when they are based on the development of expertise or supported by routine and familiarity.6 Even skills that seem to epitomise the challenge of ageing in the modern world, such as mastering information technology, can be learnt to a high degree of accuracy by older people, albeit more slowly than by younger adults.7

Mastery and wisdom

But perhaps the most interesting aspect of cognitive ageing is the extent to which cognitive skills are intertwined with mental health.8 Just as cognitive decline and depression often coexist,9 cognitive capability and mental wellbeing can be mutually supportive. We referred to mastering new technology, but mastery is more than just “know how”; it refers to a general self belief in the ability to manage important life circumstances. It develops over the life course from coping with everyday stress as much as it does from achieving success, and so arises from a sense of personal control.10 This binds cognition and emotion into a tool for developing goals, accepting and organising the information we need for these goals, establishing and protecting the right setting for their achievement, and experiencing self esteem when they are achieved.11 It is certainly possible to see the consequences of this going wrong—for example, low attainment and impaired health in adulthood following poor development of self regulation in childhood.12

Of course mastery itself is not infallible. It is vulnerable in people who are socially and economically disadvantaged; it can be undermined by uncontrollable circumstances such as serious illness; and it does decline in old age, perhaps as a result of having to accept the most inevitable health event of all, our own death.10 This acceptance hints at what is usually seen as the most mature aspect of cognitive ageing: wisdom. Wisdom has various definitions, but a common theme is the integration of specific expertise with more subtle skills such as ability to advise and manage others, to see things in context, to tolerate uncertainty (including the limits of our knowledge and capability), and to engage in spiritual reflection.13 Wisdom is, again, a “fine tuned coordination of cognition, motivation, and emotion”14 that, like mastery, evolves out of life experience, although evidence for its growth with age is surprisingly inconclusive.13

Planning for the future

Earlier we cautioned against false positivity. Nowhere is this more troublesome than in the area of planning for later life, including decisions about when to retire and how to organise finances for this transition. Here there are two challenges. Firstly, the brain circuitry that underpins the recall of detailed information also recombines these memories for mental time travel ahead, so that memory decline in ageing is accompanied by increasing difficulties in imagining the future.15 Secondly, and consistent with the intertwining of cognition and mental health, during ageing we increasingly channel our cognitive resources away from goals such as making a living or nurturing a family towards maintaining emotional stability, particularly by dampening emotional responses to negative events.16 In combination this can lead older people to contemplate a future that is “bright but blurry,” where compromised risk assessment can lead to inadequate provision for long years of retirement.15

Clearly this issue is not academic. With a looming pension crisis in the UK and elsewhere, there are recommendations for older people to continue working17 and discussion of how organisations can adapt their working practices to accommodate this change. Continuing employment will not only ease the burden of having to plan for a lengthy period beyond work but may benefit cognitive function itself, with evidence that later age at retirement is associated with delayed onset of Alzheimer’s disease.18 Reasons for this are unclear, but plausibly concern effects of engagement, or more colloquially, “use it or lose it,” which refers to the benefits of social ties as well as occupational activities. In this context it is worth noting that the combined effect of education, occupation, and mental activity was the strongest protective factor (followed by physical activity) in a recent review of modifiable risks for Alzheimer’s disease.19

Implications for practice

We naturally fear the loss of our cognitive skills, and we sometimes over-attend to apparent signs of such loss as we age. This is not to deny the reality of cognitive decline, and certainly not the devastating nature of Alzheimer’s disease, or its prevalence, or the fact that current therapies only alleviate symptoms rather than modify the disease. Intensive research efforts are underway to improve early detection of Alzheimer’s disease, with a view to developing new intervention strategies. This approach is not without its critics, although debates about medicalisation should recognise its converse—that it is not uncommon for general practitioners to dismiss symptoms of dementia as consequences of normal ageing.20 Patients with cognitive decline who are clinically distressed should always be appropriately reviewed and, if appropriate, referred for specialist evaluation.

More controversially, prescription drugs that were developed to improve cognitive function in patients with neurological disorders are increasingly sought as “neuroenhancers” by people with no diagnosed medical condition.21 As suggested, age related slowing of mental speed and decline in certain kinds of memory are virtually inevitable. However, this should not overshadow the richness of mental life in older age, where many complex cognitive skills are preserved or even advanced.

Notes

Cite this as: BMJ 2011;343:d6288

Footnotes

  • Contributors and sources: MR is professor of cognitive epidemiology at the Faculty of Population Health Sciences, School of Life and Medical Sciences, University College London. For the past 15 years he has been developing a life course approach to cognitive ageing, principally on the basis of British birth cohorts. SLH’s research combines training in medical sociology and psychiatric epidemiology, and focuses on life course approaches in social and psychiatric epidemiology, with a strong interest in the inter-relationship between cognitive ability and mental health. MR is guarantor.

  • Both authors have completed the ICJME unified disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare MR has support from the MRC for the submitted work; MR is also funded by the Wellcome Trust. SLH is funded by the NIHR Biomedical Research Centre for Mental Health. They have no non-financial interests that may be relevant to the submitted work.

  • Provenance and peer review: Commissioned; externally peer reviewed.

References