Bad habits such as smoking, heavy drinking and lack of exercise must be tackled as early as possible to boost the odds of a happy and healthy old age.

That is the message of a new peer-reviewed study, published in the Annals of Medicine (Elevate), that found smoking and other vices are associated with declines in health in people as young as 36.

The impact is even greater when these bad habits are indulged in over the long-term, state experts whose study tracked the mental and physical health of hundreds of people for more than 30 years.

Previous research has followed people from middle-age, typically for around 20 years. Studies to-date have shown that smoking and other aspects of a healthy lifestyle are adapted before the age of 30. However, in this new study a research team from Finland wanted to track people from a younger age – and to unpick, at the same time, the effect of unhealthy habits on mental health.

Using a long-running longitudinal study, in which hundreds of children who were born in the Finnish city of Jyväskylä in 1959 were followed from childhood until their early 60s, the team analyzed participants’ mental and physical health via data that was collected from surveys and medicals when they were 27 years old (326 participants) and again at age 36, 42, 50 and 61 (206 participants).

Mental health was assessed via surveys on symptoms of depression and on psychological wellbeing. Physical health was assessed by creating a metabolic risk score based on blood pressure, waist size and levels of blood sugar, cholesterol and other blood fats.

Self-health was assessed by asking the participants to rate the state of their health over the past year.

Three risky behaviours were also assessed at each point in time: smoking, heavy drinking (defined as consuming at least 7,000g/875 units of alcohol a year for women and 10,000g/1,250 units a year for men) and physical inactivity (exercising less than once a week).

Analysis of the results showed that if an individual had all three unhealthy habits – they smoked, drank heavily and were inactive – at a given point in time, their mental and physical health were poorer than if they didn’t have any of these risky behaviours. 

Depressive symptoms rose by 0.1 points, metabolic risk score rose by 0.53 points, psychological wellbeing fell by 0.1 point and self-rated health fell by 0.45 points. Depressive symptoms and psychological wellbeing was measured on a scale of 1-4; self-rated health was measured on a scale of 1-5; and metabolic risk was scored from 0-5.

Having all three unhealthy behaviours long-term was even more strongly associated with poor health. Depressive symptoms rose by 0.38 points, metabolic risk score rose by 1.49 points, psychological wellbeing fell by 0.14 points and self-rated health fell by 0.45 points.

Lack of exercise was particularly linked to poor physical health, smoking was mainly linked to poor mental health and heavy alcohol consumption was associated with declines in both mental and physical health.

Crucially, the effects were apparent by the time the participants were in their mid-30s.

“Non-communicable diseases such as heart disease and cancer cause almost three-quarters of deaths worldwide,” says lead author Dr Tiia Kekäläinen, a health scientist who has a particular interest in aging. “But by following a healthy lifestyle, an individual can cut their risk of developing these illnesses and reduce their odds of an early death.

“Our findings highlight the importance of tackling risky health behaviours, such as smoking, heavy drinking and physical inactivity, as early as possible to prevent the damage they do to from building up over the years, culminating in poor mental and physical health later in later life.

“However, it is never too late to change to healthier habits. Adopting healthier habits in midlife also has benefits for older age.”

The authors note that the study was observational and so couldn’t establish that the risky behaviours were fuelling ill health, rather than vice versa.

They say that the relationship is likely two-way. For example, someone who is stressed may drink heavily to help them cope. This could then cause problems with family and friends that lead to poorer mental well-being.

They add that the results are likely to apply to people born in Finland and other Western countries in late 1950s and in the 1960s. However, they may not be as relevant to younger generations, owing to cultural and societal changes, and partly different risky behaviors occurring nowadays.

The study’s limitations include rating each of the three habits as being equally damaging to health, instead of weighting them.

The authors also acknowledge that they only looked at three types of behavior and say that other factors, such as diet, should be included in future studies.