TOPLINE:

Current smoking was linked to a higher risk for all-cause dementia, especially vascular dementia, with the strongest effects seen in those younger than 85 years and women. It was not significantly associated with the risk for Alzheimer's dementia. Former smoking was associated with an increased risk for vascular dementia only in men, particularly those younger than 85 years.

METHODOLOGY:

• Researchers in Norway conducted a longitudinal closed cohort study using data from the Trøndelag Health Study (HUNT) to evaluate the association between smoking status and the risk for all-cause dementia, including its subtypes (vascular and Alzheimer's dementia).
• They included 8532 participants (mean age, 56.3 years) with self-reported smoking status at baseline (HUNT2, 1995-1997) and a mean follow-up duration of 21.8 years prior to cognitive assessment at HUNT4 70+ (2017-2019).
• Pack-years (20 cigarettes each day for 1 year) were calculated on the basis of the number of cigarettes smoked per day and years of smoking.

TAKEAWAY:

• At baseline, 1775 participants (21%) were current smokers, 2934 (34.4%) were former smokers, and 3823 (44.8%) were never smokers. At follow-up, 1305 participants (15%) were diagnosed with dementia.
• Current smokers had a 31% higher risk for all-cause dementia than never smokers (relative risk [RR], 1.31). Among participants younger than 85 years, women and men showed a 54% (RR, 1.54) and 36% (RR, 1.36) higher risk, respectively (P < .05 for all).
• Current smoking was significantly associated with an increased risk for vascular dementia (RR, 2.09), with a higher risk seen in participants younger than 85 years (RR, 2.62), especially men younger than 85 years (RR, 3.61). However, no significant association was observed between smoking and Alzheimer's dementia.
• Former smoking was not linked to the risk for all-cause dementia. Among former smokers, men younger than 85 years had an elevated risk for vascular dementia (RR, 2.43). Pack-years were not significantly associated with the risk for dementia.

IN PRACTICE:

"Our findings add to the literature arguing for the importance of early preventive measures and targeted public health initiatives to reduce smoking-related cognitive performance," the authors wrote.

SOURCE:

This study was led by Christian Myrstad, Norwegian National Centre for Ageing and Health, Vestfold Hospital Trust, Tønsberg, Norway. It was published online on December 16, 2025, in BMC Public Health.

LIMITATIONS:

Data on smoking exposure and most covariates were self-reported and subjected to recall bias, potentially affecting the magnitude of the association with the risk for dementia. Potential changes in smoking status over a long period between baseline and follow-up were not accounted for, leading to the possible misclassification of smoking exposure. Additionally, dementia was not assessed at baseline.

DISCLOSURES:

This study was funded by the Norwegian National Centre for Ageing and Health. One author reported participating in advisory boards of Biogen, Eisai, and Roche concerning antidementia drugs.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.