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Benzodiazepine use and risk of dementia: evidence from the Caerphilly Prospective Study (CaPS)
  1. John Gallacher1,
  2. Peter Elwood1,
  3. Janet Pickering1,
  4. Antony Bayer2,
  5. Mark Fish3,
  6. Yoav Ben-Shlomo4
  1. 1Department of Primary Care and Public Health, Cardiff University, Cardiff, UK
  2. 2Department of Geriatric Medicine, Cardiff University, Cardiff, UK
  3. 3Department of Neurology, Musgrove Park Hospital, Taunton, Somerset, UK
  4. 4School of Social and Community Medicine, University of Bristol, UK
  1. Correspondence to Dr John Gallacher, Department of Primary Care and Public Health, Cardiff University, Neuadd Meirionnydd, University Hospital of Wales, Heath Park, Cardiff CF14 4XY, UK; gallacher{at}


Background Benzodiazepine use is widespread in older people, although its benefit is uncertain.

Aim To investigate the long-term effect of benzodiazepine use upon dementia risk.

Methods A prospective cohort of men seen on five occasions over 22 years with full medication histories, repeat measures of cognitive function and a clinical diagnosis of dementia.

Results Of 1134 men with complete data, 103 (9.1%) had been taking benzodiazepines regularly at one or more phases. These men showed a marked increased incidence of dementia (OR=3.50, 95% CI 1.57 to 7.79, p=0.002), which persisted despite adjustment for psychological distress and other covariates. Men exposed in earlier phases showed a greater association than more recent exposure, counter to what one would expect if this was due to reverse causation, though we failed to demonstrate a dose–response effect with drug duration.

Conclusion The taking of benzodiazepines is associated with an increased risk of dementia.

  • Dementia
  • benzodiazepines
  • cognitive function
  • epidemiology
  • ageing
  • psychosocial factors
  • public health

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  • Baseline data were obtained from the Caerphilly Study Archive, Department of Social Medicine, Bristol University, UK.

  • Funding This work was funded by the Alzheimer's Society. The Caerphilly Study was initiated by the former MRC Epidemiology Unit (South Wales) and was funded by the Medical Research Council of the United Kingdom.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval This study was approved by South east Wales Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.