Chronic effects of shift work on cognition: findings from the VISAT longitudinal study.
Level 3 - non-randomized controlled study
Prospective longitudinal cohort study with 10-year follow-up.
PubMed 25367246 · doi:10.1136/oemed-2013-101993
What was done
A prospective cohort study (the VISAT study) followed 3,232 employed and retired workers aged 32, 42, 52, and 62 years at baseline (1996, 76% participation rate). Participants were assessed at baseline (t1), 5 years (t2), and 10 years (t3). Cognitive performance was evaluated across time points using tests of processing speed and memory, comparing 1,484 participants with current or past shift work experience to 1,635 participants without shift work experience.
What was found
Shift work was associated with lower cognitive test performance. The effect showed a dose-response relationship, with exposure durations exceeding 10 years associated with cognitive loss equivalent to 6.5 years of age-related decline within the cohort. Cognitive recovery after leaving shift work required at least 5 years. The abstract does not report raw scores, test-specific point estimates, or confidence intervals.
Why it matters
This study provides longitudinal evidence that long-term shift work causes chronic cognitive deficits that persist for years after shift work ceases.
Limits
As an observational cohort, residual confounding from lifestyle, sleep quality, and socioeconomic factors cannot be excluded. Exact quantitative scores, effect sizes, and confidence intervals are omitted from the abstract, and cognition was assessed only via speed and memory measures across three discrete time points.
Cited by
- supports Working shift work for 10 years is associated with cognitive aging equivalent to 6.5 years of accelerated decline compared to age-matched controls.