A 30-year study by the Erasmus Medical Centre among some 9,000 Rotterdammers has found that nine out of 10 people over 45 will develop one or more non-communicable diseases such as stroke, diabetes, COPD, cancer or dementia. Key risk factors are high blood pressure, being overweight and smoking.

Instead of using computer models to assess probability, this study looked at the life and habits of the inhabitants of Ommoord, an area of Rotterdam, over a period of 30 years to see when the diseases struck and which factors might have contributed.

The findings show that people with a healthy lifestyle live on average six years longer than people who smoke, are overweight and have hypertension, and that the onset of a life threatening illness is delayed by nine.

The life threatening diseases that will hit people with the three risk factors first are heart disease, cancer, COPD and diabetes. Of those who live healthily, almost 20% develop dementia as the first major disease.

The study also shows a correlation in the combination of diseases that occur. A third of the 9 out of 10 people who develop a serious illness will have a combination of various diseases. Heart disease and dementia most often occur in tandem.

‘People do not become ill at random and neither does the occurrence of these combinations. Data about this are slowly becoming available. The medical world did not pay much attention to this because doctors usually specialise in one single disease,’ research leader and neurologist Arfan Ikram told the NRC.

The small percentage of people who do not develop any of the main life-threatening diseases will die of infectious disease or a trauma such as a broken hip, Ikram said. ‘And some people who grow old healthily become so fragile that they just stop living,’ the paper quotes him as saying.

The findings underscore the importance of reducing premature deaths through smoking, hypertension and overweight, the researchers conclude.