Sammendrag
Background: The worldwide demographic pattern indicates a significant growth in the elderly population, resulting in a simultaneous increase in the prevalence of dementia. As per the World Health Organisation (WHO), the current global prevalence of dementia is about 50 million individuals. Although there is no approved treatment for the most common types of dementia. Scientists are now conducting research on modifiable risk factors that could potentially decrease the probability of having the illness. Recent studies suggest that cardiorespiratory fitness (CRF), a cardiovascular measure highly influenced by physical activity level, plays a vital role in cognitive function and sleep. Few studies have suggested a possible link between the usage of sleep medicines and an increased likelihood of developing dementia, but there is a lack of studies on the dose-response relationship between use of sleep medication and dementia risk. The primary objective of this study is to examine if there is a dose-response relationship between purchase of sleep medication and dementia, and the secondary aim is to assess if cardiorespiratory fitness modifies the association between use of hypnotics and occurrence of dementia. Methodology: This study is a prospective, cohort study including 5,223 adults who participated in the third Trøndelag Health Study (HUNT3) in 2006-08 and in the sub study HUNT4 70+ in 2017-19. Data on purchase of hypnotics was retrieved from the Norwegian Prescribed Drug Registry (NorPD) two years prior to participation in HUNT3 (2006-08). The exposure variable was Defined Daily Doses (DDDs) categorized into quartiles with participants that have not purchased prescribed hypnotics two years prior to HUNT3 (2008-08). Dementia was diagnosed according to DSM-5 criteria at participation in HUNT4 70+ (2017-19). This data is derived from the Nord-Trøndelag Health Study (HUNT). Additionally, we incorporated data related to the acquisition of hypnotics from the Norwegian Prescribed Drug Registry (NorPD), while dementia incidence was diagnosed according to DSM-5 criteria through biannual health assessments. The calculation of cardiorespiratory fitness (CRF) expressed in ml/kg/min, is obtained using a previously confirmed algorithm validated in HUNT. Binary logistic regression models with odd ratio (OR) and 95% confidence interval (CI) with adjustment for confounding factors such as age, sex, ApoE-status, education, marital status, alcohol, smoking, depressive symptoms and insomnia were employed to assess the relationship between hypnotic drugs usage, CRF and dementia risk. Results: In the fully adjusted analyses and compared to those who did not purchase hypnotics (n=4393), those in the lowest quartile of DDDs had an OR of 1.28 (95 CI; 0.87-1.86) while those in the highest quartile had an OR of 0.84 (95%CI; 0.46-1.26). The additional adjustment of insomnia made no attenuation of the association. Conclusion: Although wide confidence intervals the results indicate that there exists an inverse dose-response relationship with total use of hypnotic drugs and odds of dementia in the current sample, meaning that those purchasing most hypnotic drugs had lower dementia risk. CRF did not modify this association. These findings underscore the necessity for additional investigation, either using larger sample sizes, information on specific drug classes or more refined measuring techniques, to comprehensively investigate and fully understand these associations.