New research reveals how simple lifestyle changes can mitigate the dual threat of cardiometabolic disease and air pollution to cognitive health.
Study: Association between air pollution and lifestyle with the risk of developing mild cognitive impairment and dementia in people with cardiometabolic diseases. Image credit: NDAB Creativity / Shutterstock
In a recent study published in the journal Scientific Reportsresearchers investigated the risk of mild cognitive impairment (MCI) and dementia in patients with cardiometabolic disease (CMD). They found that, compared to healthy “normal” subjects, patients with CMD had a significantly higher risk of MCI and dementia.
Patients with three CMDs had the highest risk, with hazard ratios (HR) of 1.951 for MCI, 1.554 for all-cause dementia, 1.216 for Alzheimer’s disease, and 2.032 for vascular dementia. Higher concurrent CMD scores were associated with greater likelihood of MCI and dementia.
Air pollution exacerbated these effects, with pollutants such as PM2.5, NO2 and NOX having a particular impact. However, a healthy lifestyle moderated the strength of these associations.
Together, the present study suggests that maintaining a healthy lifestyle is critical to preventing the onset of MCI and dementia. Since both of these conditions are lifelong and remain untreated, these findings may help provide clinicians, health care providers, and patients with CMD with the information needed to address the increasing prevalence of these debilitating diseases. .
Background
“Dementia” is the general term for identifying diseases that affect people’s memory, language and other thinking skills necessary for daily activities. It is a severely debilitating condition that is known to alter patients’ personality, moods, and behaviors. Unfortunately, so far, no cure has been discovered for dementia, making prevention a priority of current research against the condition.
Alarmingly, the global prevalence of dementia is increasing at an unprecedented rate, increasing by 117% in just over two decades (1990–2016). Current estimates reveal that more than 57 million people are living with dementia, with projected economic losses exceeding $1.313 billion.
The research hypothesizes that while genetics play an important role in the prevalence of dementia, a global aging population, suboptimal lifestyle choices and increased pollution levels may exacerbate the risk of dementia.
Clinical studies have demonstrated the association between cardiometabolic diseases (CMDs, e.g., type 2 diabetes [T2DM]coronary heart disease [CHD]and stroke) and dementia, with the former almost doubling the risk of developing the latter. Similar associations between CMD and mild cognitive impairment (MCI) have been independently documented.
Specifically, individuals with two or three CMD diagnoses were found to have a significantly higher risk, with HRs for vascular dementia increasing to 6,632 in those with all three CMDs. However, the cumulative effects of multiple CMDs, environmental pollution levels and lifestyles remain unknown.
About the Study
The present study aimed to reveal the simultaneous effects of air pollution and lifestyle scores on the risk of dementia/MCI in patients with CMD. Study data were obtained from the United Kingdom (UK) Biobank, an extensive biomedical database of over 500,000 adults (ages 39–74) based in the United Kingdom. Of the 502,370 participants screened for the study, 63,689 presented incomplete sociodemographic, lifestyle, and medical information and were excluded from subsequent analyses.
UK Biobank medical history data were used to assess the number and severity of CMDs within the study cohort. The same data sets also included diagnoses of MCI and dementia, with follow-up periods of ∼15.12 years. Exposure to air pollutants such as PM2.5, PM10 and NO2 was estimated using land use regression (LUR) models.
Structured baseline questionnaires were used to assess participants’ healthy lifestyle scores. These questionnaires included seven items, including 1. diet, 2. alcohol consumption, 3. smoking status, 4. physical activity levels, 5. sedentary behavior, 6. social relationships, and 7. sleep patterns.
Statistical analyzes included latent class analysis (LCA) to identify ambient air pollutant patterns, Cox proportional regression models for dementia/MCI risk estimates, and sensitivity analyses.
Study Findings
Of the 438,681 participants included in the analyses, 17.11% (n = 75,056) were diagnosed with CMDs. Of these, 15.12% had suffered one CMD, 1.90% had two concurrent CMDs, and 0.09% had three CMDs. Statistical analyzes revealed that air pollution and poor lifestyle contributed independently to the prevalence of dementia/MCI, with dementia/MCI patients generally having poorer lifestyle choices and higher exposure to air pollution than their “normal” counterparts.
“The risk of developing mild cognitive impairment, all-cause dementia, Alzheimer’s disease, and vascular dementia in patients with CMDs was 1,951, 1,554, 1,216, and 2,032 times higher than those without CMDs, respectively.”
CMD was found to significantly increase the risk of dementia and MCI between 121 and 203%. The number of concurrent CMDs was found to compound these results—patients with two or three CMD diagnoses were significantly more likely to develop MCI or dementia than those with only one CMD.
When analyzed together, air pollutants such as PM2.5 and NO2 consistently increased the risk of dementia and MCI. Lifestyle behaviors (easily modifiable) moderate the effects of air pollution, suggesting a protective effect of these behaviors on future incidence of dementia/MCI.
conclusions
The present study is the first to assess the associations between CMD (presence and number of concurrent diagnoses) with MCI and dementia risk, while simultaneously investigating the effects of air pollution and lifestyle choices on MCI/dementia outcomes. It highlights the cumulatively increasing risk of dementia/MCI in patients with CMD directly scaling the number of concurrent CMD diagnoses.
Patients exposed to high levels of pollution but leading healthier lifestyles showed lower risks, emphasizing the modifiable nature of lifestyle factors.
Notably, while ambient air quality scores and lifestyle were found to influence MCI/dementia risk outcomes, the latter is easily modifiable and can be harnessed to protect against the onset of MCI/dementia.
