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A Woman's Guide to Increasing Healthspan, Brainspan, and Lifespan · Maddy Dychtwald · 2024
Women outlive men by roughly five years, and they spend most of those extra years sick, disabled, or in need of care — women live longer and they live worse. This book does one thing: it pulls apart two ideas that get lazily fused — living longer and living well — and then shows that what determines the second is mostly not genes and not hospitals, but what you do from your forties onward about muscle, bone, sleep, menopause, and the story you tell yourself about getting old.
Maddy Dychtwald co-founded Age Wave, a think tank that has spent four decades on a single question: how population aging rewrites economies, medicine, and families. She is not a physician, and this 2024 book (written with the journalist Kate Hanley) is not original research. It is a synthesis — she interviewed something on the order of a hundred researchers and clinicians and rearranged the evidence scattered across geriatrics, menopause medicine, exercise physiology, neuroscience and behavioural science along the arc of a woman's life. Its shelf position is clear. Peter Attia's Outlive gave the general longevity framework; Stacy Sims's ROAR gave women the training and nutrition prescription. What this book adds is the case that women's longevity is a separate problem in its own right — and it extends that case from the body to the brain, the social world, and money.
Three words, kept apart. Lifespan is how many years you get. Healthspan is how many of those you spend independent, undisabled, still able to do what you care about. Brainspan — the book's term — is how many years your cognition holds up well enough to recognise people and make your own decisions. The three lines diverge, and they diverge further for women than for men.
| Span | What it measures | Where women stand |
|---|---|---|
| Lifespan | Years lived | About five more than men on average, in nearly every country |
| Healthspan | Years lived without disability | A much smaller lead than the lifespan gap; more late years in disability and care |
| Brainspan | Years of usable cognition | Roughly two-thirds of people with Alzheimer's are women |
There is a widely cited quantification of the gap: the 2024 McKinsey Health Institute and World Economic Forum analysis estimated that women spend roughly 25% more of their lives in states of poor health than men. (A caveat worth stating: that is a modelled estimate built on global burden-of-disease data, not a direct measurement, and the number shifts with the definitions used. The direction — women accumulate more years of impaired health — holds up robustly across countries.)
Why? Because what kills men tends to be fast — heart attacks, liver disease, accidents, suicide — while what traps women tends to be slow: osteoporosis, arthritis, autoimmune disease, dementia. These are rarely immediately fatal and are very good at confining a person for years. Put bluntly, much of the time women win is saved from death, and lost again to disability.
How this changes what you look at: every number on a standard physical answers the question "am I going to die?" Almost none of them answers "at seventy-five, will I be able to get off the toilet by myself, or leave the house alone?" That second question is healthspan, and it has extremely concrete proxies — grip strength, how long you can stand on one leg, whether you can get up off the floor without using your hands, how winded two flights of stairs make you. All of them can be measured today. All of them can be trained today.
"My mother made it to ninety." "Cancer runs in my family." Most people treat lifespan as a hand dealt at birth. The estimate the book leans on is that heredity explains something like 20–30% of lifespan variation, with the remaining majority coming from behaviour, environment, access to care, and social connection. The figure traces back to Danish twin studies comparing how similarly identical and fraternal twins die.
One honest amendment: that 25% has been revised downward. A 2018 analysis built on very large genealogical datasets argued that older estimates overstated heredity because people marry people like themselves — assortative mating. Spouses die at similar ages not because of shared genes but because of shared conditions, and the older models were quietly booking that as heritability. That analysis put the true figure below 10%. The direction doesn't change; it strengthens. More of this is movable than you assume.
Why this has to come first: it is the book's licence to operate. If lifespan were mostly genetic, everything that follows — training, sleep, hormones, mindset — would be consolation. Only if the bulk really is modifiable does "start doing something at forty-five" stop being self-flattery. It also marks a boundary: this is not a claim that you control everything. Luck, birth circumstances and access to care are real variables. The claim is narrower and sturdier: within the part you do control, there is far more room than intuition suggests.
This is the book's strongest section and the fundamental reason it exists alongside general longevity books. A great deal of modern medical evidence was generated in male bodies and then extrapolated to female ones by default.
The timeline is specific. A 1977 FDA guidance excluded women of childbearing potential from early-phase clinical trials — the intent was to protect foetuses, the effect was that an entire generation of drugs was dosed and its side effects characterised without women in the data. Not until the NIH Revitalization Act of 1993 was the inclusion of women in federally funded clinical research mandated. Further upstream, in the laboratory, even the animals were male by default — female animals were said to introduce noise because of their oestrous cycles — and the NIH only began requiring sex as a biological variable in preclinical study design in 2016.
The consequences are not abstract. Heart disease is the standard example: the textbook symptoms — crushing chest pain radiating down the left arm — come largely from male samples, while women having heart attacks more often present with nausea, extreme fatigue, jaw or back discomfort, breathlessness. The result is more misclassification and more delay. Drug metabolism differs systematically too; the famous case is the sleep drug zolpidem, whose recommended dose for women the FDA cut in 2013 — nearly two decades after approval — after it emerged that women had substantially higher next-morning blood levels and greater driving impairment.
How this changes what you do: when you meet any health recommendation, add one question — whose bodies produced this conclusion? That is not conspiracy thinking, it is the documented history of the field. And because of the gap, the evidence base in menopause, bone density, and women's cardiovascular risk is thinner than people assume; plenty of questions still have no high-quality answer. The real cost of the data gap isn't that women get wrong advice; it's that they get advice nobody has actually tested.
This is the section that most needs careful handling and carries the most practical value.
In 2002, the oestrogen-plus-progestin arm of the large randomised Women's Health Initiative (WHI) trial was stopped early, and the coverage said it raised breast cancer and cardiovascular risk. The effect was a cliff: hormone therapy prescriptions fell by something like 80% over the following years, and a generation of women and a generation of doctors were frightened off at the same time.
Later reanalysis rewrote the conclusion on two points: the magnitude of the absolute risk, and when in life the therapy is started.
| The 2002 public impression | The reappraisal | |
|---|---|---|
| Size of risk | Hormone therapy causes cancer and harms the heart | The relative risk increases corresponded to small absolute increments |
| Who was studied | Assumed to stand for all menopausal women | Average enrolment age around 63; most were more than a decade past menopause |
| Timing | Not considered | The timing hypothesis: starting before 60, or within ten years of menopause, changes the risk-benefit picture substantially |
| Position today | Avoid unless desperate | For symptomatic women in that window without contraindications, most professional bodies hold that benefits generally outweigh risks — individually assessed |
The boundary has to be drawn just as firmly, or this becomes a different kind of overcorrection. Hormone therapy is not a longevity drug. Major guidelines — including the US Preventive Services Task Force — explicitly do not recommend it for the primary prevention of chronic disease; it has not been shown to prevent dementia or extend life; and it is not for women with contraindications such as a history of breast cancer or blood clots. What has been re-evaluated is its value as treatment for women with symptoms — not its value as an anti-aging intervention for everyone.
Why this section matters beyond medicine: it is the most vivid real-world consequence of the data gap. A trial designed to answer "can hormones prevent chronic disease in older women?" had its answer transplanted onto "should a fifty-year-old with hot flushes and broken sleep take anything?", and the price was twenty years of untreated symptoms. The transferable lesson: the boundary of a study's applicability deserves to be remembered better than its headline.
If only one action item survived from this book, it would be this one. Oestrogen protects both bone and muscle; when it withdraws, both curves steepen at once.
Bone. In the first five to seven years after menopause a woman can lose up to 20% of her bone density. Osteoporosis produces essentially no symptoms until the first fracture — and roughly one in two women over fifty will sustain an osteoporosis-related fracture in her remaining lifetime. Hip fractures are especially brutal: they are frequently the event that ends independent living.
Muscle. Sarcopenia is the age-related loss of muscle mass and strength — on the order of 3–8% per decade after thirty, accelerating after sixty. Muscle is not just strength: it is the body's largest glucose sink (and therefore tied to insulin sensitivity and diabetes risk), it is your shock absorber in a fall, and it is the thing that stands you up out of a chair, off the floor, out of the bath.
The prescription is counterintuitive — not walking, loading. Bone responds to pull and impact: muscle tugging on bone, and the shock of a heel striking the ground, are the signals that tell bone to reinforce itself. So what works is resistance training, jumping and impact work, stairs; swimming and cycling are excellent for other reasons but do little for bone density, because the body isn't bearing weight. Muscle responds to progressive overload: the load has to keep climbing, not stay forever at two-pound dumbbells for many repetitions. Protein intake has to go up too — with age, the same amount of protein triggers less muscle synthesis (anabolic resistance), so the move is not toward eating lighter but toward eating sturdier.
How this changes what you see: most people file "exercise" under cardiovascular fitness and weight management, and file strength training under bodybuilding. On the longevity ledger, muscle and bone are not cosmetic — they are the infrastructure of independent old age, and they are among the very few systems guaranteed to decline with age that can also demonstrably be partly reversed by training. Every load you lift today is buying whether you can get yourself off the floor at eighty.
About two-thirds of people living with Alzheimer's are women. The easy explanation — women live longer and age is the dominant risk factor — covers part of it, but is broadly considered insufficient on its own. Other lines under investigation: the oestrogen withdrawal of menopause may affect the brain's energy metabolism; the APOE4 gene, the main genetic risk factor, appears to amplify risk more in women; and historical differences in education and occupation shaped cognitive reserve. Honestly stated: all of these mechanisms remain contested and none is settled.
Cognitive reserve is the concept worth taking from this section. It names the brain's buffer — its ability to keep functioning despite pathology. Given the same burden of plaques and damage, one person is demented and another is still running her own life; the difference is reserve. The analogy: reserve is a bank balance, pathology is a standing debit. You don't fully control the debit rate, but the balance can be built up over decades — and the things that build it are known: education and continued learning, work that is complex rather than repetitive, socialising that requires thought, additional languages, instruments.
The most underrated item is sleep. During sleep the brain's glymphatic system — a clearance pathway that becomes markedly more active in sleep and flushes metabolic waste — removes far more debris, including the beta-amyloid associated with Alzheimer's. And menopause is precisely when women's sleep quality falls off a cliff: hot flushes, night sweats, insomnia become brain-health risks in their own right. That reframes "I slept badly, I feel rough" into "I slept badly, and the brain is running a debt." (The mechanism is well supported in animal work; the causal chain in humans is still being established.)
The book spends real space on two things that don't look like medicine: how you regard getting old, and whether there are people around you.
Age beliefs. In a well-known study, Becca Levy at Yale found that people with positive perceptions of aging outlived those with negative ones by about 7.5 years. The proposed mechanism is that negative age stereotypes shape health-seeking behaviour, willingness to exercise, and stress response — "that's just age, nothing to be done," and so a treatable problem goes untreated. Honestly: discount that number. It comes from an observational study of a few hundred people; reverse causation is hard to rule out (healthier people naturally feel better about aging); an effect of 7.5 years is suspiciously large by epidemiological standards; and replication has been mixed. Plausible in direction, doubtful in magnitude — which is how every "attitude adds N years" claim should be read.
Social connection. The evidence here is harder than for mindset. Meta-analyses have repeatedly found strong social ties associated with substantially better survival, with an effect size often compared to quitting smoking, and the US Surgeon General issued a public health advisory on loneliness and isolation in 2023. The part specific to women: women are more likely to live alone in later life — they live longer and are often younger than their partners — and they are more often the family caregiver, which is itself an intense, prolonged and routinely ignored health risk.
The book files one more item here: sense of purpose. People with a clear sense of purpose show lower mortality across multiple cohort studies. The mechanism may well be indirect — purposeful people keep better hours and take better care of themselves — but treating "what am I adding twenty years for?" as a question that requires a serious answer is exactly this book's posture: healthspan is not a medical target, it's a design problem for a life.
This is Age Wave's home territory and the piece most health books skip. The logic is blunt: women live longer while earning less and taking more career interruptions for childbirth and caregiving, which leaves them with smaller retirement savings — and the three stack into a significantly higher chance of outliving their money.
The book doesn't treat this as a finance lesson but loops it back into health: late-life medical and long-term care costs are the least predictable and most portfolio-destroying category of spending there is, so closing the healthspan gap is itself the most effective form of financial risk management. Said another way: the strength you build starting at forty-five is bone density and it is also care costs you may never have to pay. In longevity, health and money are not two ledgers. They are one.
This isn't a theory so much as a chain of argument. Taken apart, it runs in five steps:
1. Women outlive men by about five years, and a large share of those years is spent in disability — the question was never "can I get more time," it's "what kind of days are the extra ones?"
2. Count three lines separately: lifespan, healthspan, brainspan. A standard physical answers only the first, and the other two decide what your old age is actually like.
3. Heredity explains maybe a quarter of lifespan, possibly less — this is the book's licence: most of it is in your hands.
4. From 1977 to 1993 women of childbearing age were systematically excluded from trials; lab animals weren't required to include females until 2016. Much of the health advice you've been given was extrapolated from male data.
5. Twenty years of untreated menopause followed from transplanting a chronic-disease finding about 63-year-olds onto fifty-year-olds with hot flushes — a study's boundary of applicability deserves to be remembered better than its headline.
6. Up to a fifth of bone density can go in the five to seven years after menopause, and about half of women over fifty will fracture because of it. Osteoporosis has no symptoms until the first break.
7. What works for bone and muscle is load, impact and progressive overload — not walking and two-pound dumbbells. Swimming and cycling are fine for the heart and do little for bone.
8. Muscle is not a cosmetic project; it is the infrastructure of independent old age — the weight you lift today buys whether you can get off the floor at eighty.
9. Cognitive reserve is a bank balance and pathology is a standing debit: you don't set the debit rate, but the balance is built over decades — learning, complex work, demanding conversation, and badly underrated sleep.
10. In longevity, health and money are one ledger: closing the healthspan gap is the most effective financial risk management available to you.