Letters to the Editor
Issues concerning sarcopenia in ageing
adults
Sir,
Cruz-Jentoff et al. present a valuable review of the difficult field of clinical measurements of sarcopenia [1]. However, several problems remain that limit full acceptance of their cal-culations. First, all or most of the current methods employed for measurement of muscle mass or fat-free mass (FFM) have associated assumptions and technical issues, and questionable accuracy in assessing small changes [2]. Further, although extensively discussed by the authors, the major current anatom-ical definitions of sarcopenia are clearly error-prone. Given the very wide variations of muscle mass (about half of FFM) within the normal population, the use of the ‘sex-specific lowest 20% of study group’ or of ‘>2 standard deviations below mean of young adults’ seem poor definition criteria. For example, using direct measurement of body fat by inert gas absorption to accurately calculate FFM by difference (±2%), the range of FFM for healthy Americans of similar sex, age and height is very wide (over 40%) [3]. Many (most?) bigger normal persons could lose over 20% of FFM (or muscle mass) without being appreciated as sarcopenic while smaller normals might be labelled sarcopenic with only minor loss [3].
Although the concept of‘primary age-related’ muscle loss has been advanced for over 70 years, most supporting animal studies have been largely misleading due to problems associated with cross-sectional observations, to unappreci-ated disease within animal colonies or to the selectively longer lifespan of smaller mammals [4]. Some years ago, our laboratory carried out longitudinal observations of several colonies of male Sprague-Dawley rats, using serial in vivo measurements for body fat of individuals from early maturity to old age, as well as parallel histochemical studies. No loss of muscle mass or FFM was apparent in healthy rats observed to 900 days (when colonies were terminated) [4,5]. Nine hundred days is thought approximately equivalent to human age 90. Similarly, when direct in vivo measurement of body fat was used to establish individual fat-free masses (±2%) for carefully studied small groups of young men, young women, older men and older women (ages 60–75), no significant reductions of FFM with age were demonstrated [3]. Were the older human subjects still too young to exhibit sarcopenia?
Early, often occult, illnesses are highly prevalent at the advanced years when sarcopenia becomes evident, so the isolation and documentation of‘primary age-related sarcope-nia’ prove increasingly complicated. In view of the inherent broad ranges of muscle mass and muscle function within the normal population, it would appear that establishing valid
changes (and defining the causes) of individual muscle mass and function will require detailed longitudinal observations over periods of time.
Conflict of interest
None declared.To read more Letters or to respond to any Age and Ageing articles, please visithttp://bit.ly/AALetters.
GERSONT. LESSER
New York University School of Medicine, New York, NY, USA gtl1@nyu.edu
References
1. Cruz-Jentoft AJ, Landi F, Schneider SM et al. Prevalence of and interventions for sarcopenia in ageing adults: a systematic review. Report of the International Sarcopenia Initiative (EWGSOP and IWGS). Age Ageing 2014; 43: 748–59. 2. Baracos V, Caserotti P, Earthman CP et al. Advances in the
science and application of body composition measurement.
JPEN J Parenter Enteral Nutr 2012; 36: 96–107.
3. Lesser GT, Deutsch S, Markofsky J. Use of an independent measurement of body fat to evaluate overweight and under-weight. Metabolism 1971; 20: 792–804.
4. Lesser GT, Deutsch S, Markofsky J. Aging in the rat: longitudinal and cross-sectional studies of body composition. Am J Physiol
1973; 225: 1472–8.
5. Lesser GT, Deutsch S, Markofsky J. Fat-free mass, total body water, and intracellular water in the aged rat. Am J Physiol 1980; 238: R82–90.
doi: 10.1093/ageing/afu207 Published electronically 19 January 2015
Re: Issues concerning sarcopenia in ageing
adults
Sir,
We appreciate the comments of Prof. Lesser to our complex systematic review on the prevalence and interventions of sarcopenia.
Our systematic reviewed tried to show the state of the art in this topic, and not to propose new methodologies not pro-posed by the authors of the primary studies, nor to deeply
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discuss methodological issues involved in the design of indi-vidual studies.
We fully agree that many problems persist unsolved in the field of measuring muscle mass. There is a common confu-sion between fat free mass and muscle mass (muscle is below 40% of fat free mass in older adults); a wide discussion on cut-off points that have to be used to define low muscle mass when defining sarcopenia [1,2]; and sensitivity to change of muscle mass measurements using different techniques has not been properly assessed [3]. It is known that body weight masks changes in fat mass and fat free mass in elderly subjects [4], so fat free mass may not consistently reflect changes in muscle mass. This is particularly true in obese ageing indivi-duals, as muscle may decrease together with liver or heart en-largement, resulting in a misleading stability in fat free mass.
However, we do believe that the concept of ‘primary age-related’ muscle mass loss has been confirmed in different longitudinal studies in aging and old humans using different methods to measure muscle mass, although it seems clear that muscle function and muscle quality impair more signifi-cantly than muscle mass, due to changes in muscle compos-ition [5–8].
These and other problems in measuring muscle mass, to-gether with the low predictive value of muscle mass for most outcomes lead to our groups and others to emphasise the role of muscle function upon the mass in the modern sarco-penia definitions [9,10].
Longitudinal changes found in muscle mass and function in individual subjects would, of course, be relevant for clinical practice, as is true for most biological measures, but may not lead to a better understanding of sarcopenia as a condition.
Conflicts of interest
None declared.
To read more Letters or to respond to any Age and Ageing articles, please visithttp://bit.ly/AALetters.
A. J. CRUZ-JENTOFT, Y. BOIRIE, T. CEDERHOLM, on behalf of the
International Sarcopenia Initiative sarcopenia@eugms.org
References
1. Cawthon PM, Peters KW, Shardell MD et al. Cutpoints for low appendicular lean mass that identify older adults with clinically significant weakness. J Gerontol A Biol Sci Med Sci 2014; 69:
567–75.
2. McLean RR, Shardell MD, Alley DE et al. Criteria for clinically relevant weakness and low lean mass and their longitudinal association with incident mobility impairment and mortality: the foundation for the National Institutes of Health (FNIH) sarcopenia project. J Gerontol A Biol Sci Med Sci 2014; 69:
576–83.
3. Mijnarends DM, Meijers JM, Halfens RJ et al. Validity and reli-ability of tools to measure muscle mass, strength, and physical performance in community-dwelling older people: a systematic
review. J Am Med Dir Assoc 2013; 14: 170–8.
4. Gallagher D, Ruts E, Visser M et al. Weight stability masks sar-copenia in elderly men and women. Am J Physiol Endocrinol
Metab 2000; 279: E366–75.
5. Mitchell WK, Williams J, Atherton P et al. Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front Physiol 2012; 3: 260. 6. Delmonico MJ, Harris TB, Visser M et al. Longitudinal study
of muscle strength, quality, and adipose tissue infiltration. Am
J Clin Nutr 2009; 90: 1579–85.
7. Shimokata H, Ando F, Yuki A, Otsuka R. Age-related changes in skeletal muscle mass among community-dwelling Japanese: a 12-year longitudinal study. Geriatr Gerontol Int 2014; 14
(Suppl 1): 85–92.
8. Frontera WR, Reid KF, Phillips EM et al. Muscle fiber size and function in elderly humans: a longitudinal study. J Appl Physiol (1985) 2008; 105: 637–42.
9. Cruz-Jentoft AJ, Baeyens JP, Bauer JM et al. Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People. Age Ageing 2010; 39: 412–23.
10. Fielding RA, Vellas B, Evans WJ et al. Sarcopenia: an undiag-nosed condition in older adults. Current consensus definition: prevalence, etiology, and consequences. International working group on sarcopenia. J Am Med Dir Assoc 2011; 12: 249–56.
doi: 10.1093/ageing/afu208 Published electronically 19 January 2015
A diagnosis for £55: what is the cost of
government initiatives in dementia case
finding
Sir,
The incentivisation of General Practitioners (GPs) to diagnose dementia began in 2011 with updated dementia strategy. This policy has become more explicit, with the aim to meet the Prime Minister David Cameron’s pledge to in-crease the rates of dementia diagnoses from 48 to 67% by April 2015. The department of health has produced a £55 monetary incentive for GP practices to diagnosis dementia. We do not believe that this strategy will have the desired effect in reducing the dementia gap because of increased referrals of people with cognitive complaints not due to neu-rodegenerative dementia. This creates a risk of false-positive diagnosis [1], which can have a devastating consequence if incorrectly given a label of dementia We have compared the current case mix attending the Sheffield neurology memory clinic from October 2012 to December 2013 to two previous service evaluations in 2004 and 2006 (Figure1). This showed an increase in proportion of patients with psychiatric ( pre-dominantly depression) and also functional memory pro-blems (defined and discussed elsewhere [2, 3], which is in keeping with previous data from Larner et al. [4,5]).
Not only are we concerned about not reducing the memory gap, but the incentivisation of diagnoses of demen-tia has the potendemen-tial to make things worse. The demendemen-tia
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Letters to the Editor
