The number of people living with dementia is rising globally as life expectancy increases. Dementia is a multifactorial disease. Due to the ubiquity of radiation exposure in medical and occupational settings, the potential association between radiation and dementia, and its subtypes (Alzheimer's and Parkinson's disease), is of particular importance. There has also been an increased interest in studying dementia risks in connection with the long-term manned space travel proposed by The National Aeronautics and Space Administration (NASA). To our knowledge, the findings from epidemiological studies of ionizing radiation and dementia have not been previously synthesized using a meta-analytic approach. Our aim was to systematically review the literature on this topic, and use meta-analysis to generate a summary measure of association, assess publication bias and explore sources of heterogeneity across previous studies. We identified five types of exposed populations for this review: 1. survivors of atomic bombings in Japan; 2. patients treated with radiation therapy for cancer or other diseases; 3. occupationally exposed workers; 4. those exposed to environmental radiation; and 5. patients exposed to radiation from diagnostic radiation imaging procedures. We included studies that considered incident or mortality outcomes for dementia and its subtypes. Following PRISMA guidelines, we systematically searched the published literature indexed in PubMed between 2001 and 2022. We then abstracted the relevant articles, conducted a risk-of-bias assessment, and fit random effects models using the published risk estimates. After we applied our eligibility criteria, 18 studies were identified for review and retained for meta-analysis. For dementia (all subtypes), the summary relative risk was 1.11 (95% CI: 1.04, 1.18; P = 0.001) comparing individuals receiving 100 mSv of radiation to those with no exposure. The corresponding summary relative risk for Parkinson's disease incidence and mortality was 1.12 (95% CI 1.07, 1.17; P <0.001). Our results provide evidence that exposure to ionizing radiation increases the risk of dementia. However, our findings should be interpreted with caution due to the small number of included studies. Longitudinal studies with improved exposure characterization, incident outcomes, larger sample size, and the ability to adjust for effects of potential confounders are needed to better assess the possible causal link between ionizing radiation and dementia.

Changes to water conditions due to eutrophication and climate change have resulted in the proliferation of harmful algal blooms in freshwater and marine environments globally, including in Canadian lakes. We developed and administered an online survey to evaluate the awareness of these blooms and the accompanying health risks in a sample of New Brunswick waterfront cottage and homeowners. The survey was distributed to lake and cottage associations in New Brunswick and was completed by 186 eligible respondents. Participants were asked to about information about the water quality of their lake, awareness about algae blooms, sociodemographic and cottage characteristics, and complete a self-rated measure of physical and mental health. While approximately 75% of participants reported that the quality of their lake water was good or very good, 40% indicated that algae blooms were a concern. We found no statistically significant differences in self-reported physical or mental health between those who were aware of algae blooms at their cottage and those who weren’t (p > 0.05). Participants expressed concern about the impacts of algal blooms on the health of their pets, and wildlife. While climate change was the most identified cause of algal blooms, there was substantial heterogeneity in the responses. Taken together, the findings from our survey suggest that cottage owners in New Brunswick are aware and concerned about the impacts of algae blooms, however, there is a need to provide additional information to lake associations about the causes of these blooms.

Changes to water conditions due to eutrophication and climate change have resulted in the proliferation of algae blooms in freshwater and marine environments globally, including in Canadian lakes. We developed and administered an online survey to evaluate the awareness of these blooms and the perceptions of health risks in a sample of New Brunswick waterfront cottage and homeowners. The survey was distributed to lake and cottage associations in New Brunswick and was completed by 186 eligible respondents (18 years of age or older). Participants were asked about the water quality of their lake, awareness about algae blooms, sociodemographic and cottage characteristics, and to complete a self-rated measure of physical and mental health. While approximately 73% of participants reported that the quality of their lake water was good or very good, 41% indicated a concern about algae blooms. We found no differences in self-reported physical or mental health between those who were aware of algae blooms at their cottage and those who were not ( p > 0.05). Participants expressed concerns about the impacts of algae blooms on the health of their pets, and wildlife. While climate change was the most frequently identified cause of algae blooms, there was substantial heterogeneity in the responses. In addition, the reporting of the presence and frequency of algae bloom varied between respondents who lived on the same lake. Taken together, the findings from our survey suggest that cottage owners in New Brunswick are aware and concerned about the impacts of algae blooms, however, there is a need to provide additional information to them about the occurrence and causes of these blooms.