Physical activity, cognitive decline, and risk of dementia: follow-up of Whitehall II study
The authors of the 28 year follow-up of Whitehall II cohort study [1] conclude that there is no evidence of neuroprotective effects of physical activity. This conclusion is of utmost public health importance. The authors should take care in using the term “dementia”. De facto it`s a post mortem diagnosis. Dementia according to DSM-5, is a general term that encompasses different types of distinct symptoms and brain abnormalities. The authors acknowledge the ascertainment of dementia status as a limitation of the study, but It is of outstanding relevance for investigation of the role of physical activity on different subtypes of dementia such Alzheimer's disease or vascular dementia [2].
According to the latest revised diagnostic criteria for Alzheimer's disease (Alzheimer's Disease and Related Disorders Association), the confidence in diagnosing mild cognitive impairment (MCI) due to Alzheimer's disease is raised with the use of neuro imaging (MRI, PET) and application of biomarkers based on measures in the cerebrospinal fluid (CSF) -- for example, CSF amyloid beta (Aß) [3], CSF tau and the CSF tau/ABeta ratio [4]. These tests, added to core clinical criteria, might increase the sensitivity or specificity of a testing strategy but the heterogeneity of research leads to a state of uncertainty regarding the value in current clinical practice. In the study of Sabia and colleagues [1] there is no information about the dementia subtypes, diagnostic criteria, their complex difficulties and the possible influence on the results. The conclusion about the length of the prodromal phase and its potential impact is incomplete without this information, respectively. There are significant differences between Alzheimer's disease and vascular dementia from the appearance of the first cognitive symptoms and rate of accelerated decline for different cognitive functions before dementia diagnosis [5].
REFERENCES
1. Sabia S et al. Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study. BMJ. 2017;357:j2709
2. Guure CB et al. Impact of Physical Activity on Cognitive Decline, Dementia, and Its Subtypes: Meta-Analysis of Prospective Studies. Biomed Res Int 2017;9016924. doi: 10.1155/2017/9016924. Epub 2017 Feb 7.
3. Ritchie C et al. Plasma and cerebrospinal fluid amyloid beta for the diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI). Cochrane Database Syst Rev. 2014 Jun 10;(6):CD008782. doi: 10.1002/14651858.CD008782.pub4.
4. Ritchie C et al. CSF tau and the CSF tau/ABeta ratio for the diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI). Cochrane Database Syst Rev. 2017 Mar 22;3:CD010803. doi: 10.1002/14651858.CD010803.pub2.
5. Laukka EJ et al. Preclinical cognitive trajectories differ for Alzheimer's disease and vascular dementia. J Int Neuropsychol Soc. 2012 Mar;18(2):191-9. doi: 10.1017/S1355617711001718. Epub 2012 Jan 23.
Competing interests:
No competing interests
21 August 2017
Detlef Degner
Associate Professor of Psychiatry, assistant medical director
Department of Psychiatry, Medical School of Georg-August University, Goettingen
Rapid Response:
Physical activity, cognitive decline, and risk of dementia: follow-up of Whitehall II study
The authors of the 28 year follow-up of Whitehall II cohort study [1] conclude that there is no evidence of neuroprotective effects of physical activity. This conclusion is of utmost public health importance. The authors should take care in using the term “dementia”. De facto it`s a post mortem diagnosis. Dementia according to DSM-5, is a general term that encompasses different types of distinct symptoms and brain abnormalities. The authors acknowledge the ascertainment of dementia status as a limitation of the study, but It is of outstanding relevance for investigation of the role of physical activity on different subtypes of dementia such Alzheimer's disease or vascular dementia [2].
According to the latest revised diagnostic criteria for Alzheimer's disease (Alzheimer's Disease and Related Disorders Association), the confidence in diagnosing mild cognitive impairment (MCI) due to Alzheimer's disease is raised with the use of neuro imaging (MRI, PET) and application of biomarkers based on measures in the cerebrospinal fluid (CSF) -- for example, CSF amyloid beta (Aß) [3], CSF tau and the CSF tau/ABeta ratio [4]. These tests, added to core clinical criteria, might increase the sensitivity or specificity of a testing strategy but the heterogeneity of research leads to a state of uncertainty regarding the value in current clinical practice. In the study of Sabia and colleagues [1] there is no information about the dementia subtypes, diagnostic criteria, their complex difficulties and the possible influence on the results. The conclusion about the length of the prodromal phase and its potential impact is incomplete without this information, respectively. There are significant differences between Alzheimer's disease and vascular dementia from the appearance of the first cognitive symptoms and rate of accelerated decline for different cognitive functions before dementia diagnosis [5].
REFERENCES
1. Sabia S et al. Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study. BMJ. 2017;357:j2709
2. Guure CB et al. Impact of Physical Activity on Cognitive Decline, Dementia, and Its Subtypes: Meta-Analysis of Prospective Studies. Biomed Res Int 2017;9016924. doi: 10.1155/2017/9016924. Epub 2017 Feb 7.
3. Ritchie C et al. Plasma and cerebrospinal fluid amyloid beta for the diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI). Cochrane Database Syst Rev. 2014 Jun 10;(6):CD008782. doi: 10.1002/14651858.CD008782.pub4.
4. Ritchie C et al. CSF tau and the CSF tau/ABeta ratio for the diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI). Cochrane Database Syst Rev. 2017 Mar 22;3:CD010803. doi: 10.1002/14651858.CD010803.pub2.
5. Laukka EJ et al. Preclinical cognitive trajectories differ for Alzheimer's disease and vascular dementia. J Int Neuropsychol Soc. 2012 Mar;18(2):191-9. doi: 10.1017/S1355617711001718. Epub 2012 Jan 23.
Competing interests: No competing interests