What actually kills people, by decade

Health anxiety is usually pointed at the wrong targets.

People worry about the rare disease they read about in a news article. They do not think much about the risks that are actually proportional to their decade. Too much attention goes on the unlikely. Not enough goes on the probable.

This is not medical advice. It is a way of thinking about where action is most likely to matter.

The data is from Australian mortality statistics. I use it as a reference point for a general pattern. It is not a universal fact. The pattern holds across most rich countries, though the exact numbers vary.

The starting point

Take a fit, non-smoking man in his late 20s in a developed country. This is the baseline.

All-cause mortality runs at roughly 1 in 1,200 per year. The risk of a life-threatening event is closer to 1 in 600 to 800. Many are survived, which brings the actual death rate down further.

These are estimates, not precise measurements. The actual number depends on lifestyle, location, and specific demographics. The point is not the exact figure. The absolute risk is low. The composition of that risk changes completely as you age.

Under 40: external causes dominate

For most people under 40, the dominant causes of death and serious harm are external.

Accidents and injury account for roughly 30 to 35 percent. Road accidents, workplace incidents, and falls account for most of that.

Suicide and mental health-related causes account for roughly 25 to 30 percent.

Together, those two categories make up more than half of all deaths in this age group.

That is worth sitting with. The biggest health risks for someone in their 20s and 30s are not cardiovascular disease or cancer. They are driving, mental health, and physical risk-taking.

Why external causes dominate: behaviour, not biology

The reason external causes dominate is not random bad luck. It is that the body in your 20s and 30s is extremely resistant to internal failure. The cardiovascular system, the immune system, and the metabolic system are all functioning well unless they have been severely abused. Biological failure at this age is rare. The vulnerabilities are behavioural.

Road risk is the clearest case. Young men die on the road at far higher rates than anyone else. This is my estimate of a known pattern in high-income country mortality data. The overrepresentation is not biology. It is speed, alcohol, fatigue, and phone use. These are all addressable. A consistent defensive driving posture removes a large fraction of the biggest single risk in this age group. No phone in hand. Never impaired. Rest before long drives. No speeding.

Mental health risk is harder to measure but just as large. Social isolation, poor sleep quality, and unmanaged stress are the leading behavioural contributors. The window for acting early is wide. Most clinical depression and anxiety disorders respond well to early treatment. The outcomes degrade sharply when people wait.

Physical injury tracks with risk tolerance and substance use. It is the category with the most variance. Some people in this age group have near-zero risk from this bucket. Others have very high risk. The behaviour, not the age, drives it.

The implication is practical. If you want to lower your risk in this decade, focus on the levers that actually move the number. Driving behaviour, sleep quality, alcohol management, and mental health monitoring.

After 50: internal degeneration takes over

The picture flips around age 50.

Cardiovascular disease rises to around 30 to 35 percent of deaths. Cancers rise to around 30 percent. Together they account for roughly two-thirds of deaths.

Lifestyle inputs from your 30s and 40s start expressing themselves. Blood pressure ignored for ten years. Chronic inflammation from poor diet. Fitness left to decline. These show up in the data as cardiovascular events and cancer diagnoses.

The lifetime risk of a major condition is over 70 percent by age 80. This covers cardiovascular events, cancer diagnoses, and type 2 diabetes. The risk is heavily back-loaded. Most of it is concentrated in the 60s and 70s.

The window between your 30s and your late 50s is when the inputs are laid down. The bill arrives later.

The 80/20 framework

Ignore ultra-rare disease. It is real and largely unactionable for most people at most ages. Reading about it does not change your risk. Worrying about it is just anxiety with a medical gloss on top.

Build around the buckets that actually move the number.

Right now — the things that matter in your 20s and 30s, with the reasoning:

• Driving safety. Road accidents are the number one external cause of death for young men in high-income countries. A consistent safe-driving posture reduces this risk by a large fraction. No alcohol, no phone, no speeding, rest before long drives. This is not complicated.
• Sleep quality. A person sleeping six hours or less consistently is operating with degraded judgment, elevated cortisol, and compromised immune function. Sleep is the simplest single lever in the under-40 risk basket. It requires no equipment and no spending.
• Mental health monitoring. Early identification of clinical depression or anxiety produces dramatically better outcomes than crisis intervention. If something has felt wrong for more than a few weeks, that is information worth acting on.
• Alcohol and substance management. Alcohol is involved in a significant proportion of road deaths, suicide attempts, and serious injury events. The interaction effects between alcohol and other risk categories are severe. It is not about abstinence. It is about understanding that alcohol raises risk in multiple categories at once.
• Regular skin checks. Skin cancer is the most common cancer in high-income countries. The under-40 risk is lower than for older age groups, but early detection at any age produces much better outcomes. One skin check a year is the whole job.

Future-proofing — the things that matter from your mid-30s onwards, with the reasoning:

• Blood pressure, tracked and managed early. Elevated blood pressure causes no symptoms for years while damaging arterial walls. The earlier it is identified, the more options there are. A standard doctor visit is the whole fix. Most people who have elevated blood pressure have not checked recently.
• ApoB. Most people know LDL cholesterol. ApoB is a more direct measure of cardiovascular risk. It counts the actual particles that can penetrate arterial walls. Normal LDL with high particle count (measured by ApoB) still represents significant risk. It is the metric most preventive cardiologists would track for themselves. A standard blood panel does not include it by default. Ask for it.
• Fasting glucose. Type 2 diabetes does not appear suddenly. It is the endpoint of a decade of metabolic resistance. Fasting glucose is measurable via a standard blood test. Elevated fasting glucose at 35 is a signal worth acting on. By 45 it is often already a problem.
• Lean muscle mass. Maintained through strength training, not just cardio. Muscle mass is a metabolic reserve that protects against insulin resistance, falls, and recovery from illness. It is easier to maintain than to rebuild after a long gap.
• VO2 max. A more accurate predictor of longevity than body weight or BMI. It is trainable. Zone 2 cardio — low intensity, sustained — is the most efficient way to improve it. Most people who do "cardio" are not doing Zone 2. Zone 2 is the effort level where you can hold a conversation but would not want to.
• Screening on schedule. Colonoscopy, skin checks, age-appropriate cancer screening. These are not optional extras. They are the point at which the "inputs laid down in your 30s" conversation becomes a clinical reality. Starting on schedule is when screening works. Waiting until there are symptoms is often too late.

Most items require action well before the problem appears. Ten to 20 years is typical. That is the whole point. The best time to affect your cardiovascular health at 60 is when you are 40.

The reframe on health anxiety

Here is what the data says about health anxiety.

The person reading a news article about a rare condition at midnight and worrying about it is not wrong to care about their health. They are wrong about how the odds are spread. The odds that rare condition harms them in the next decade are very low. The odds that their driving, their sleep, or unmanaged mental health harms them are much higher.

Anxiety pointed at a 0.1 percent risk while ignoring a 5 percent risk is a calibration failure. It is not a moral failure. It is a result of how health information gets distributed. News articles about rare diseases get clicks. Articles about driving safely and sleeping eight hours do not.

The reframe is not "do not worry about your health." It is "point the worry at the right targets."

The useful frame

The risks before 40 are mostly external. Most are preventable through behaviour.

The risks after 50 are mostly internal. Most are preventable through habits built before damage accumulates.

The overlap is striking. Almost none of it is what you read about in medical articles at midnight.

Attention is a finite resource. Pointing it at the right buckets, in the right decade, is most of the game.

Same principle applies to a business. The boring maintenance is what moves the number. Book a 30-min AI discovery call and we'll map it out.