Authors: Elizabeth Blackburn and Elissa Epel
The singular importance of this book on telomeres lies in the critically influential role these ‘repeating segments of non-coding DNA‘ perform in maintaining health and warding off the ravages of ageing. The authors set out to share what they believe is crucial information which will enable people to ‘cultivate’ their telomeres so that they can optimise their chances of living longer and better lives. The authors also outline how people can turn back the clock on ‘telomere attrition‘ and thereby counteract the devastation wrought by the diseases of ageing. Whilst the book advocates such lifestyle changes as diet and exercise to promote telomere health and delay ageing, it nevertheless also advocates the benefits of developing healthy attitudes towards growing old – a process it depicts as consisting of ‘richer and more complex’ positive emotional experiences. The book’s strength lies in the refreshing way it balances, on one hand, the benefits of maintaining health, and on the other hand, the value of adopting positive stereotypes of old age. This is a finely tuned antidote to what the authors portrayed as the fruitless yearning for lost youth which leads to dissatisfaction and unhappiness (pages 7-8, xvii, 14 and 36-39).
In their eloquent characterisation of telomeres, the authors compared them to aglets, the protective plastic tips found at the end of shoelaces, an analogy which captures their function as ‘physical buffers‘ which protect chromosomes during cell division. The authors also explained how the rate at which telomeres shorten with each cell division determines how fast the cells will age, and how soon they will die. Referring to the Hayflick limit – ‘the natural limit that human cells have for dividing’ – the authors noted that ‘critically short‘ telomeres are the ‘stop switches‘ which terminate cell division and bring the lives of cells to an end. The book however emphasised that the speed of telomere shortening, maximum at about the age of 75 years, is reversible, an indication that telomere shortening and ageing are both ‘dynamic‘ processes that can be accelerated, slowed, or reversed. And at the heart of preventing telomere shortening is telomerase, the enzyme that lengthens telomeres and promotes tissue regeneration. The authors asserted that telomerase is effectively a way of getting around the Hayflick limit, and they supported this by pointing out that stem cells, by possessing an abundance of telomerase, are not constrained by the normal restrictions to perpetual cell division. Beyond accelerating the process of ageing, the book explored several other downsides of short telomeres, many of which are negative thought patterns such as cynical hostility, mind-wandering, pessimism, rumination, and thought suppression (pages 6-22, 48-49, 57 and 101-109).
Perhaps the most revealing feature of the book is its discussion of the factors that promote telomere shortening, a theme dominated by the overwhelming role of chronic stress. In this exposition, the authors portrayed how the intensity and duration of stress correlates with telomere length, the effect setting in as early as three weeks after the stress begins. It was however particularly interesting that the authors attributed telomere shortening to the anticipated threat, rather than to the actual experience, of stress. In explaining the mechanism whereby chronic stress shortens telomeres, the authors noted the role played by cortisol and epinephrine, the stress hormones which entrench ‘a state of physiological vigilance‘ and which accelerate ageing. The major causes of chronic stress the book highlighted were chronic diseases – sources of ‘tremendous psychological strain‘; caregiving – ‘one of the most profound stresses a person can experience’; physical, sexual, and emotional trauma; and burnout from work. Beyond stress, other telomere-shortening triggers the book discussed included mental health problems; for example, it refers to how depression shortens telomeres in the hippocampus (page pages 62-67, 75-83 and 139-141).
In depicting the wider health implications of telomeres, far beyond their effect on ageing, the book addressed the contribution of short telomeres to the development of chronic diseases such as diabetes. In this narration, the authors focused on the inability of cells with short telomeres to attract other cells to help them regenerate when they are damaged. The book also pointed out that this limitation is mediated by high levels of senescence associated secretory phenotype (SASP); this molecule accumulates in cells with short telomeres and promotes chronic inflammation – a process the authors termed ‘inflammaging‘. Another mechanism by which short telomeres cause disease is symbolised by Alzheimer’s disease, a dementia that may arise because short telomeres impair the regeneration of the memory mediating hippocampal cells. In this regard, it is pertinent that the authors referred to the increased risk of Alzheimer’s disease from mutations in genes which maintain telomeres length, for example TERT and OBFC1. It is also relevant that the book reviewed how short telomeres trigger cancer by exposing chromosomes to damage, and by impairing the ability of immune cells to inhibit excessive cellular proliferation. An interesting complement to this theme is the book’s exploration of inherited telomere syndromes – disorders which are associated with mutations in 11 genes, and which manifest with accelerated ageing, scarred lungs, low blood counts, weak immunity, and cancer (pages 24-31, 34-45, 42-44 and 61).
A most insightful aspect of the book is the first author’s description of the groundbreaking and Nobel Prize winning research she carried out to reveal the nature of telomeres. It was her discerning experiments on Tetrahymena, the pond scum, which convincingly demonstrated that telomeres are made of repeating DNA sequences of TTAGGG bases located at the ends of chromosomes. Significantly, it was her observation that the length of telomeres varied across the organism’s chromosomes that demonstrated that telomeres, under certain conditions, can increase in length – an attribute not shared by other parts of the DNA. The author went further to isolate telomerase, the enzyme which restores the length of telomeres by serving as a template for creating new DNA. Her work therefore demonstrated the link between telomerase and cell longevity, and with the way the body defends itself from chronic diseases. Conversely, her work also highlighted ‘the dark side‘ of telomerase – the tendency for the enzyme to trigger the ‘uncontrolled cell growth that is the hallmark of cancer‘. Reinforcing this association, the book referred to the research finding that telomerase is overactive in up to 90% of cancers (pages 45-60).
The most practical theme of the book is undoubtedly the helpful recommendations it makes to enable the maintenance of telomere length. Amongst the suggestions the authors advocated are omega-3-rich foods such as seaweed, fish, and algae, and diets low in processed meats and carbonated drinks. They particularly stressed the importance of reducing dietary sugar, a measure which they argued ‘may be the single most beneficial change you can make to your diet’. Encouraging regular moderate aerobic endurance exercises and high intensity interval training, the book pointed out that these not only lengthen telomeres, but they also reduce cortisol levels and improve the immune system. To reduce the impact of chronic stress, the book urged people to develop stress resilience such as by positively reappraising stressful situations, by avoiding rumination, and by eschewing excessively self-critical thoughts. The authors also encouraged the habit of converting stressful situations into challenges – a practice they justified by noting that people who ‘face stress with a rousing sense of challenge’ have longer telomeres. Other telomere restoring behaviours the book endorsed are good sleep hygiene, mindfulness practices, cultivating a conscientious personality, and practicing resilient thinking techniques such as uni-tasking, thought awareness, reflection, meditation, and self-compassion (pages 72-74, 84, 90, 106-128, 169-178, 189-202, 211-220 and 231-237).
This is a unique book which finely blends hard science with self-help, drawing its recommendations directly from what is known about telomeres. Intended for the lay reader, the prose is simple and completely devoid of complicated terms and complex concepts. The book’s use of tables, diagrams, and reflective boxes also go further to entrench the lessons it teaches. The simplification of the text however meant relevant details such as names of the telomere syndromes, were omitted. The details of the author’s award winning work was also very sketchy and not emphasised enough. There was a repetitive emphasis on the health consequences of short telomeres but this is probably because the book is primarily a practical rather than academic text; this may also explain why some of the evidence cited were based on self-reports. The subject is however relevant to healthcare and society as a whole.
This book highlights a relatively new and important feature of chromosomes which have widespread influence on health and longevity. Whilst it discusses the science, the emphasis by the authors was on the application of the knowledge to daily life. The self-help was detailed and practical, and easily adaptable. The book highlights the link between telomere length and health outcomes, and the emphasis is strong enough to encourage beneficial lifestyle changes. This is important in medicine and I recommend the book to all doctors.
Publisher, Place, Year: Orion Spring, London, 2017
Number of chapters: 13
Number of pages: 396
Star rating: 5