Outdoor artificial light at night and risk of early-onset dementia: A case-control study in the Modena population, Northern Italy

Elena Mazzoleni; Marco Vinceti; Sofia Costanzini; Caterina Garuti; Giorgia Adani; Giulia Vinceti; Giovanna Zamboni; Manuela Tondelli; Chiara Galli; Simone Salemme; Sergio Teggi; Annalisa Chiari; Tommaso Filippini

doi:10.1016/j.heliyon.2023.e17837

Outdoor artificial light at night and risk of early-onset dementia: A case-control study in the Modena population, Northern Italy

Heliyon. 2023 Jun 29;9(7):e17837. doi: 10.1016/j.heliyon.2023.e17837. eCollection 2023 Jul.

Authors

Elena Mazzoleni¹, Marco Vinceti^{1

2}, Sofia Costanzini³, Caterina Garuti^{1

4}, Giorgia Adani¹, Giulia Vinceti^{5

6}, Giovanna Zamboni^{5

6}, Manuela Tondelli^{6

7}, Chiara Galli^{6

7

8}, Simone Salemme^{5

6}, Sergio Teggi³, Annalisa Chiari⁶, Tommaso Filippini^{1

9}

Affiliations

¹ Environmental, Genetic and Nutritional Epidemiology Research Center (CREAGEN), Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
² Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
³ DIEF Department of Engineering "Enzo Ferrari", University of Modena and Reggio Emilia, Modena, Italy.
⁴ Department of Medical and Surgical Sciences for Mothers, Children and Adults, Post Graduate School of Pediatrics, University of Modena and Reggio Emilia, Modena, Italy.
⁵ Department Center for Neurosciences and Neurotechnology, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
⁶ Neurology Unit, Modena Policlinico-University Hospital, Modena, Italy.
⁷ Primary Care Department, Modena Local Health Authority, Modena, Italy.
⁸ Department of Neuroscience, Psychology, Pharmacology and Child Health (NeuroFARBA), University of Florence, Florence, Italy.
⁹ School of Public Health, University of California Berkeley, Berkeley, CA, USA.

Abstract

Background: Dementia is a neurological syndrome characterized by severe cognitive impairment with functional impact on everyday life. It can be classified as young onset dementia (EOD) in case of symptom onset before 65, and late onset dementia (LOD). The purpose of this study is to assess the risk of dementia due to light pollution, and specifically outdoor artificial light at night (LAN).

Methods: Using a case-control design, we enrolled dementia patients newly-diagnosed in the province of Modena in the period 2017-2019 and a referent population from their caregivers. We geo-referenced the address of residence on the date of recruitment, provided it was stable for the previous five years. We assessed LAN exposure through 2015 nighttime luminance satellite images from the Visible Infrared Imaging Radiometer Suite (VIIRS). Using a logistic regression model adjusted for age, sex, and education, we calculated the risk of dementia associated with increasing LAN exposure, namely using <10 nW/cm²/sr as reference and considering ≥10-<40 nW/cm²/sr intermediate and ≥40 nW/cm²/sr high exposure, respectively We also implemented non-linear assessment using a spline regression model.

Results: We recruited 58 EOD cases, 34 LOD cases and 54 controls. Average LAN exposure levels overlapped for EOD cases and controls, while LOD cases showed higher levels. Compared with the lowest exposure, the risk of EOD associated with LAN was higher in the intermediate exposure (OR = 1.36, 95% CI 0.54-3.39), but not in the high exposure category (OR = 1.04, 95% CI 0.32-3.34). In contrast, the risk of LOD was positively associated with LAN exposure, with ORs of 2.58 (95% CI 0.26-25.97) and 3.50 (95% CI 0.32-38.87) in the intermediate and high exposure categories, respectively. The spline regression analysis showed substantial lack of association between LAN and EOD, while almost linear although highly imprecise association emerged for LOD.

Conclusions: Although the precision of the estimates was affected by the limited sample size and the study design did not allow us to exclude the presence of residual confounding, these results suggest a possible role of LAN in the etiology of dementia, particularly of its late-onset form.

Keywords: Case-control study; Early-onset dementia; Late-onset dementia; Light at night; Light pollution; Risk.