Forskningsartikler

Background: The 2024 Lancet Commission report on dementia identified 14 modifiable dementia risk factors. The Norwegian HUNT study uniquely includes data collection of all 14 risk factors in the same individuals throughout adulthood, as well as a study-specific dementia diagnosis. We aimed to evaluate the potential for dementia prevention associated with these 14 risk factors, along with three additional sociodemographic risk factors in this retrospective cohort.

Methods: This retrospective cohort study included data on participants with study-specific diagnosis from the HUNT4 70+ study (2017-19) and was linked with national administrative registries (1960-2018) and earlier HUNT surveys (1984-2008) with data on dementia risk factors at ages 35-92 years. Inverse probability weighting was applied to account for non-response. Logistic regression estimated dementia risk associated with exposure to less education in early adult life (age <45 years), hearing loss, high LDL cholesterol, depression, traumatic brain injury, physical inactivity, diabetes, smoking, hypertension, obesity, excessive alcohol use in midlife (age 45-65 years), and social isolation, air pollution, and vision loss in late life (age >65 years). Midlife occupational physical activity and marital and employment status were added to the Lancet model. The potential for dementia prevention was assessed using population attributable fraction (PAF).

Findings: Between Sept 1, 2017, and Feb 28, 2019, 19 403 individuals were invited to participate and 9745 participants (1525 with dementia, 8220 without dementia) were included. 4445 (45·6%) of 9745 participants were male and 5300 (54·4%) were female. The total PAF for the 14 Lancet risk factors was 50·9% (95% CI 37·7-61·4). Including family-related and work-related risk factors increased the PAF to 54·9% (42·3-64·7; p<0·0001). When these factors were added for women, the total PAF increased from 48·0% (95% CI 29·4-61·7) to 52·2% (34·2-65·3; p=0·0090), whereas no significant change was observed in men (56·2% [95% CI 35·5-70·2] to 56·7 [95% CI 36·1-70·6]; p=0·71).

Interpretation: Addressing all 14 Lancet risk factors could prevent over half of all dementia cases. Adding factors related to marital and occupational status offers additional preventive potential, particularly among women.

Merete Ellingjord-Dale, Bjørn Heine Strand, Vegard Skirbekk, Bernt Bratsberg, Teferi Mekonnen, Ekaterina Zotcheva, Geir Selbæk, Yaakov Stern, Asta Kristine Håberg, Bo Engdahl

Background
Smoking is considered a risk factor for dementia. Nevertheless, uncertainty regarding the associations with dementia subtypes and the effects of quitting remains. In this large longitudinal population-based cohort study, we investigated smoking as an independent risk factor for all-cause dementia. Second, we investigated the associations with dementia subtypes.

Methods
We included participants from the Trøndelag Health Study (HUNT) and collected their smoking status at baseline (HUNT2, 1995-97). We assessed cognitive status at follow-up two decades later (HUNT4 70+, 2017-19, N = 8,532) and collected pack-years. We handled missing data with multiple imputations and estimated relative risks (RRs) with Poisson regression after adjustment for covariates and stratification by age and sex.

Results
Current smokers had a 31% increased dementia risk (RR 1.31, 95% confidence interval (CI) 1.12–1.52), women <85 at follow-up had a 54% increased risk (RR 1.54, 95% CI 1.20–1.98), and men <85 had a 36% increased risk (RR 1.36, 95% CI 1.01–1.82). We found no associations in persons 85+. Current smokers had an increased risk for vascular dementia but not for Alzheimer’s dementia. Pack-years were not associated with increased dementia risk, and former smoking was only associated with vascular dementia in men.

Conclusions
Current smoking was associated with an increased risk of dementia. Among those 85+ at follow-up, being a smoker 20+ years earlier was not associated with an increased risk of dementia, probably because death was a competing risk. In former smokers, there were no significant associations with dementia. Our results add to the literature an optimism about the effects of changing smoking habits and may encourage smoking cessation.

Christian Myrstad, Marie Larssen, Bo Engdahl & Geir Selbæk

Abstarct:

The prevalence of Alzheimer’s disease neuropathological changes (ADNCs), the leading cause of cognitive impairment, remains uncertain. Recent blood-based biomarkers enable scalable assessment of ADNCs¹. Here we measured phosphorylated tau at threonine 217 in 11,486 plasma samples from a Norwegian population-based cohort of individuals over 57 years of age as a surrogate marker for ADNCs. The estimated prevalence of ADNCs increased with age, from less than 8% in people 58–69.9 years of age to 65.2% in those over 90 years of age. Among participants aged 70 years or older, 10% had preclinical Alzheimer’s disease, 10.4% had prodromal Alzheimer’s disease and 9.8% had Alzheimer’s disease dementia. Furthermore, among those 70 years of age or older, ADNCs were present in 60% of people with dementia, in 32.6% of those with mild cognitive impairment and in 23.5% of the cognitively unimpaired group. Our findings suggest a higher prevalence of Alzheimer’s disease dementia in older individuals and a lower prevalence of preclinical Alzheimer’s disease in younger groups than previously estimated.

Dag Aarsland, Anita Lenora Sunde, Diego A. Tovar-Rios, Antoine Leuzy, Tormod Fladby, Henrik Zetterberg, Kaj Blennow, Kübra Tan, Giovanni De Santis, Yara Yakoub, Burak Arslan, Hanna Huber, Ilaria Pola, Lana Grötschel, Guglielmo Di Molfetta, Håvard K. Skjellegrind, Geir Selbaek & Nicholas J. Ashton