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Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study.

Abstract Objective To test the hypotheses that physical activity in midlife is not associated with a reduced risk of dementia and that the preclinical phase of dementia is characterised by a decline in physical activity.Design Prospective cohort study with a mean follow-up of 27 years.Setting Civil service departments in London (Whitehall II study).Participants 10 308 participants aged 35-55 years at study inception (1985-88). Exposures included time spent in mild, moderate to vigorous, and total physical activity assessed seven times between 1985 and 2013 and categorised as "recommended" if duration of moderate to vigorous physical activity was 2.5 hours/week or more.Main outcome measures A battery of cognitive tests was administered up to four times from 1997 to 2013, and incident dementia cases (n=329) were identified through linkage to hospital, mental health services, and mortality registers until 2015.Results Mixed effects models showed no association between physical activity and subsequent 15 year cognitive decline. Similarly, Cox regression showed no association between physical activity and risk of dementia over an average 27 year follow-up (hazard ratio in the "recommended" physical activity category 1.00, 95% confidence interval 0.80 to 1.24). For trajectories of hours/week of total, mild, and moderate to vigorous physical activity in people with dementia compared with those without dementia (all others), no differences were observed between 28 and 10 years before diagnosis of dementia. However, physical activity in people with dementia began to decline up to nine years before diagnosis (difference in moderate to vigorous physical activity -0.39 hours/week; P=0.05), and the difference became more pronounced (-1.03 hours/week; P=0.005) at diagnosis.Conclusion This study found no evidence of a neuroprotective effect of physical activity. Previous findings showing a lower risk of dementia in physically active people may be attributable to reverse causation-that is, due to a decline in physical activity levels in the preclinical phase of dementia.
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Journal Title bmj (clinical research ed.)
Publication Year Start




PMID- 28642251
OWN - NLM
STAT- MEDLINE
DA  - 20170623
DCOM- 20170707
LR  - 20170707
IS  - 1756-1833 (Electronic)
IS  - 0959-535X (Linking)
VI  - 357
DP  - 2017 Jun 22
TI  - Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of 
      Whitehall II cohort study.
PG  - j2709
LID - 10.1136/bmj.j2709 [doi]
AB  - Objective To test the hypotheses that physical activity in midlife is not
      associated with a reduced risk of dementia and that the preclinical phase of
      dementia is characterised by a decline in physical activity.Design Prospective
      cohort study with a mean follow-up of 27 years.Setting Civil service departments 
      in London (Whitehall II study).Participants 10 308 participants aged 35-55 years 
      at study inception (1985-88). Exposures included time spent in mild, moderate to 
      vigorous, and total physical activity assessed seven times between 1985 and 2013 
      and categorised as "recommended" if duration of moderate to vigorous physical
      activity was 2.5 hours/week or more.Main outcome measures A battery of cognitive 
      tests was administered up to four times from 1997 to 2013, and incident dementia 
      cases (n=329) were identified through linkage to hospital, mental health
      services, and mortality registers until 2015.Results Mixed effects models showed 
      no association between physical activity and subsequent 15 year cognitive
      decline. Similarly, Cox regression showed no association between physical
      activity and risk of dementia over an average 27 year follow-up (hazard ratio in 
      the "recommended" physical activity category 1.00, 95% confidence interval 0.80
      to 1.24). For trajectories of hours/week of total, mild, and moderate to vigorous
      physical activity in people with dementia compared with those without dementia
      (all others), no differences were observed between 28 and 10 years before
      diagnosis of dementia. However, physical activity in people with dementia began
      to decline up to nine years before diagnosis (difference in moderate to vigorous 
      physical activity -0.39 hours/week; P=0.05), and the difference became more
      pronounced (-1.03 hours/week; P=0.005) at diagnosis.Conclusion This study found
      no evidence of a neuroprotective effect of physical activity. Previous findings
      showing a lower risk of dementia in physically active people may be attributable 
      to reverse causation-that is, due to a decline in physical activity levels in the
      preclinical phase of dementia.
FAU - Sabia, Severine
AU  - Sabia S
AD  - Centre for Research in Epidemiology and Population Health, INSERM U1018,
      Universite Paris-Saclay, Hopital Paul Brousse, Paris, France.
AD  - Department of Epidemiology and Public Health, University College London, London, 
      UK.
FAU - Dugravot, Aline
AU  - Dugravot A
AD  - Centre for Research in Epidemiology and Population Health, INSERM U1018,
      Universite Paris-Saclay, Hopital Paul Brousse, Paris, France.
FAU - Dartigues, Jean-Francois
AU  - Dartigues JF
AD  - INSERM U1219, University of Bordeaux, Bordeaux, France.
FAU - Abell, Jessica
AU  - Abell J
AD  - Centre for Research in Epidemiology and Population Health, INSERM U1018,
      Universite Paris-Saclay, Hopital Paul Brousse, Paris, France.
AD  - Department of Epidemiology and Public Health, University College London, London, 
      UK.
FAU - Elbaz, Alexis
AU  - Elbaz A
AD  - Centre for Research in Epidemiology and Population Health, INSERM U1018,
      Universite Paris-Saclay, Hopital Paul Brousse, Paris, France.
FAU - Kivimaki, Mika
AU  - Kivimaki M
AD  - Department of Epidemiology and Public Health, University College London, London, 
      UK.
FAU - Singh-Manoux, Archana
AU  - Singh-Manoux A
AD  - Centre for Research in Epidemiology and Population Health, INSERM U1018,
      Universite Paris-Saclay, Hopital Paul Brousse, Paris, France.
AD  - Department of Epidemiology and Public Health, University College London, London, 
      UK.
LA  - eng
PT  - Journal Article
DEP - 20170622
PL  - England
TA  - BMJ
JT  - BMJ (Clinical research ed.)
JID - 8900488
SB  - AIM
SB  - IM
MH  - Adult
MH  - Aged
MH  - Aged, 80 and over
MH  - Cognitive Dysfunction/etiology/*physiopathology/prevention & control
MH  - Dementia/etiology/*physiopathology/prevention & control
MH  - England/epidemiology
MH  - *Exercise
MH  - Female
MH  - Follow-Up Studies
MH  - Health Behavior
MH  - Humans
MH  - Life Style
MH  - Male
MH  - Middle Aged
MH  - Neuroprotection
MH  - Neuropsychological Tests
MH  - Proportional Hazards Models
MH  - Prospective Studies
MH  - Risk Factors
COI - Competing interests: All authors have completed the ICMJE uniform disclosure form
      at http://www.icmje.org/coi_disclosure.pdf (available on request from the
      corresponding author) and declare: no support from any organisation for the
      submitted work; no financial relationships with any organisations that might have
      an interest in the submitted work in the previous three years; no other
      relationships or activities that could appear to have influenced the submitted
      work.
EDAT- 2017/06/24 06:00
MHDA- 2017/07/08 06:00
CRDT- 2017/06/24 06:00
PST - epublish
SO  - BMJ. 2017 Jun 22;357:j2709. doi: 10.1136/bmj.j2709.