Three unhealthy behaviors linked to a 2.5 fold higher risk
Past research has demonstrated that unhealthy behaviors (physical inactivity, poor diet, smoking, alcohol abstinence or consumption beyond recommended limits) have a negative effect on health such as excessive drinking raise the risk of conditions like lung cancer and liver disease. Few studies have examined the combined effect of unhealthy behaviors on disability.
Researchers from France and the United Kingdom investigated the link between unhealthy behaviors, with each behavior examined separately and in combination and the hazard ratio and the hazard of disability over a 12 year follow-up.
For the study researchers used data from the Three-City (3C) Dijon cohort study (a prospective cohort study that recruited community dwelling older people aged 65 years or over from electoral rolls in three French cities (Bordeaux, Dijon, Montpellier) from 1999 and 2001. Participants were interviewed at that time about their lifestyle, including information on smoking, diet, physical activity, and alcohol drinking. They were then followed for the incidence of disability over 12 years.
Disability status was assessed six times over 12 years, at baseline and waves 1, 2, 4, 5, and 6.
Three levels of disability were assessed: mobility; which assessed the ability to do heavy work around the house, walk half a mile, and climb stairs, instrumental activities of daily living (IADL); IADLs included the ability to use a telephone, manage medications and money, use public or private transport, and do shopping, and, additionally for women, to prepare meals and do housework and laundry, and and basic activities of daily living (ADL); ADLs included bathing, dressing, toileting, transferring from bed to chair and eating. Participants were considered disabled if they could not perform at least one activity without any given level of help.
Data on health behaviors came from the baseline questionnaire. Researchers classified behaviors as healthy/unhealthy.
Physical activity, consumption of fruit and vegetables less than once a day, smoking (current or having quit smoking less than 15 years ago), and no (abstention or former) or heavy consumption of alcohol were all considered as unhealthy behaviors. Characteristics were also identified that may influence the relation between unhealthy behaviors and disability such as cardiovascular disease, diabetes, depression, high BMI and cancer.
At baseline, 488 (9.9%) of 4931 participants were disabled and excluded from the analyses; a further 195 participants dropped out of the study before wave 1 and did not die during the follow-up.
During a total follow-up of 12 years 3982 participants contributed 27 141 person years and 1236 were women developed disability (incidence 45.5/1000 person years). Incidence of disability increased from 3.4/1000 in participants aged 65-70 years to 288.0/1000 in those over 90 years. During the follow-up, 992 participants died, of whom 702 were not disabled at their last examination before death.
Participants reporting low or intermediate physical activity had a 72% increased risk of disability, independently of the presence of other unhealthy behaviors; similarly, the increased risk was 24% for people who consumed fruits and vegetables less than once a day and 26% for current or short-term ex-smokers. Participants with all three unhealthy behaviors were twice as likely to develop disability. There was no association between alcohol drinking and disability. About 30% of the association between unhealthy behaviors and disability was explained by higher body mass index, lower cognitive function, depressive symptoms, traumatisms, chronic conditions, and cardiovascular disease.
Compared with people without unhealthy behaviors, those with three unhealthy behaviors had a 2.5-fold increased hazard of disability. Among several potential mediators, chronic conditions, and, to a lesser extent, depressive symptoms, trauma, and body mass index partially explained this association.
The researchers write “Our findings are in line with studies on mortality, chronic diseases, or cognition showing unhealthy behaviors to have cumulative effects. These findings have important public health implications, as these behaviors are potentially modifiable, and interventions aimed at promoting a healthy lifestyle may help to prevent the onset of disability. In addition, our findings suggest that interventions targeting multiple behaviors may carry greater benefit than simpler interventions.”
This new study appears in the British Medical Journal; BMJ.