Air pollution linked to increased use of psychiatric services in people with dementia

Exposure to air pollution is associated with increased use of psychiatric services in people with dementia, researchers at King’s College London (KCL) have suggested.

A new study showed that people with dementia living in areas with the highest exposure to nitrogen dioxide (NO₂) were 27% more likely to use community mental health services than those living in areas with the lowest exposure levels.

Higher pollution levels were shown to negatively affect physical health and social function resulting in dementia patients accessing mental health services for depression and psychosis, as well as behavioural problems linked to dementia.

The study was published in the journal BMJ Mental Health, and the authors suggest that reducing levels of air pollution could reduce the use of community mental health services by people with dementia.

Air quality analysis

The researchers examined data from 5,024 people who had a primary diagnosis of dementia. Some 54% of participants had been diagnosed with Alzheimer’s disease, which is caused by plaque deposits and tangles in the brain; 20% had vascular dementia, which is caused by damage to blood vessels in the brain; and 26.5% had other or unspecified dementia.

Pollution levels at patient addresses across the London boroughs of Southwark, Lambeth, Lewisham and Croydon were estimated using an air quality model based on data from 2008 to 2012. The researchers linked concentrations of two major air pollutants – NO₂ and particulate matter (PM_2.5 and PM₁₀) – with anonymised electronic mental health records of community mental health service use.

Cognitive function was determined using the Mini Mental State Exam, and the Health of the Nation Outcomes Scale (HONOS65+) was used to measure physical health and social activity over the study period.

The researchers found that the higher the level of exposure, the greater the use of these services for people with dementia, particularly for exposure to NO₂ and for people with vascular dementia.

‘Strong associations‘ between dementia and air pollution

Dr Amy Ronaldson, research fellow at KCL and first author, said: ‘Our study showed that there were stronger associations for patients with vascular dementia, which is caused by reduced blood flow to the brain, and implies that air pollution might impact the development of vascular dementia more than other dementia types.’

The researchers found that those living in areas with the highest exposure to NO₂ were nearly a third more likely to access community mental health services than those with the lowest exposure to NO₂.

Dementia patients exposed to the highest level of tiny particulate matter (PM_2.5) were 33% more likely to use community mental health services. The associations were still evident nine years from the start of the study.

Air pollution was shown to negatively impact physical health and social functioning, which may partially explain how air pollution leads to more use of community mental health teams in people with dementia, the researchers suggested.

Dr Ioannis Bakolis, from KCL and the study’s senior author, said the team estimated that if the particulate matter exposure in London fell in line with recommendations by the World Health Organization, ‘the number of community mental health service contacts by people with dementia could be reduced by 13% a year’.

The researchers say that more work is needed to understand how air pollution impacts other aspects of dementia-related care.

This article was originally published by our sister publication Nursing in Practice.