Correlates of biological age in postmenopausal life

Przegląd Antropologiczny – Anthropological Review • Vol. 69, 15-26 (2006)
Correlates of biological age in postmenopausal life
Maria Kaczmarek, Edyta Lasik
Institute of Anthropology, Adam Mickiewicz University, Umultowska 89,
61-614 Poznań, Poland; E-mail: [email protected]
ABSTRACT
This study provides an evaluation of selected socio-demographic
and lifestyle factors associated with biological age (BA) of 461 women who
have experienced natural menopause. Data were drawn from a cross-sectional
survey carried out in Poland, between 2000-2004 in a middle-aged cohort of
women. For purposes of the present study, demographic, social, health and wellbeing, and lifestyle behavior aspects were conducted by means of a questionnaire. Anthropometric and physiological parameters were included in analyses.
BA was computed as a composite z-score of 23 biomarkers according to the
method proposed by Borkan and Norris [1980a, 1986]. Profiles of BA were
plotted against the study factors. The findings revealed that urban women with
high educational attainment and normal BMI were more likely to be biologically
younger than their peers from rural areas with poor educational attainment,
overweight and obesity (p < 0.01). Women who self-rated their health as “good”,
were physically active and current or former HRT users who were likely to be
biologically younger than their counterparts (p < 0.01). Lifestyle behavior characteristics such as smoking cigarettes and alcohol consumption appeared to be
weakly associated with the BA of the postmenopausal women. This study demonstrates that a knowledge of the biological status of postmenopausal women
and evaluation of factors associated with younger biological age might be of help
in extending their healthy life span.
KEY WORDS women, health, biomarkers, social background, lifestyle behaviors
Prz. Antropol.–Anthropol. Rev. (2006), vol. 69, pp. 15-26, Fig. 1, Tables 3. ISBN 83922875-2-5, ISSN 0033-2003
The concept of biological age (BA),
successfully used in assessing the rate of
maturation in physical growth of children and adolescents, has also been recommended for use in the later stages of
life [BORKAN et al. 1982]. Physiological
aging, unlike clearly defined variants
of growing patterns, includes all timedependent changes in structure and
function of the organism that eventually
contribute to diminished efficiency and
increased vulnerability to disease and
16
M. Kaczmarek, E. Lasik
death. The meaning of BA is therefore
often explained as “a quantity expressing the ‘true global state’ of the aging
organism better than the corresponding
chronological age” or as “age corresponding better to ‘true life expectancy’
of the individual than his or her chronological age” [KLEMERA and DOUBAL
2006: 240]. Much of the controversy
regarding the determination of BA stems
from the methodological problems associated with the definition of BA. The
most common determinations of BA
include a set (battery) of age-dependent
variables (biomarkers), and either the
multiple linear regression model, factor
analysis (FA) or principle component
analysis (PCA) as the statistical method
for computing the outcome age [HEIKKINEN et al. 1974, FURUKAWA et al.
1975, WEBSTER and LOGIE 1976, BROWN
and FORBES 1976, BORKAN and NORRIS
1980a].
The long-term pattern of demographic change in Poland, the decrease in
mortality and increase in life expectancy, has resulted in an increased number of women in middle and later life1.
By the year 2030 a projected 10.3 million women of 45 years and older will
be living in Poland, nearly double the
current number. Women’s life expectancy this year will be 83.3 years2. The
dramatic increase in life expectancy has
led to women expecting to live more
than a third of their lives after menopause. For women in the post-reproductive life stage, social background,
socioeconomic status and lifestyle be1
Population Census 2002, www.stat.gov.pl
Population Projection of Poland until 2030, Central
Statistical Office in Warsaw, www.stat.gov.pl/dane
2
havior are critical factors in health and
well-being [Commission of the European Communities 1997]. The permissive social background is claimed
to warrant easier access to resources,
health and medical care. Positive lifestyle behaviors are considered to favor
“good old age” [UTTLEY and CRAWFORD
1994].
Aiming to meet women’s efforts
to cope successfully with unpleasant
symptoms, diseases and disability in
later life, many attempts have been
made to determine factors associated
with aging. The purpose of this study is
to evaluate social and lifestyle factors
associated with younger biological age
in post-reproductive life stage.
Materials and Methods
This study was part of a cross-sectional survey conducted in Poland between
2000 and 2004. Data for this study were
obtained from a sub-sample of 461
postmenopausal women. Only women
with natural menopause were included
in the sample. The natural menopause
was defined as spontaneous cessation
of menstruation recognized as the last
menstrual period (LMP) determined
after 12 months of amenorrhea [World
Health Organization 1996].
The investigation included a menopause-specific questionnaire3, with anthropometric, physiological and biochemical parameters. For purposes of
the present study, demographic, social,
health and well-being, and lifestyle be3
Kaczmarek M., 2000, Polish version of Menopause-Specific Questionnaire, its validity and reliability, Unpublished manuscript
Correlates of biological age in postmenopausal life
havior aspects of the questionnaire were
considered. 23 biomarkers, known to
have a positive or negative linear correlation with chronological age were included in the battery. They were as follows:
- Cardiovascular: systolic (SBP) and
diastolic (DBP) blood pressure
(mmHg), mean arterial pressure,
MAP = ((2 x diastolic) + systolic)/ 3
(mmHg).
- Biochemical: total cholesterol (TCH;
mmol/l), glucose (G; mmol/l), total
protein (TP; g/dl) and electrolytes,
potassium (K; mmol/l) and sodium
(Na; mmol/l).
- Hematological: haemoglobin (HGB;
mmol/l), red blood cells (RBC;
mln/mm3) and erythrocyte sedimentation rate (ESR; OB) (mm/h).
- Anthropometric: weight (W; kg),
height (H; cm), waist (WS; cm), hip
(HS; cm), forearm (FS; cm) and
breast (BS; cm) circumferences, waist
hip ratio (WHR; cm) calculated by
dividing the waist measurement by
the hip measurement, and body mass
index (BMI; kg/m2) calculated as
body weight in kg divided by the
square of standing height.
- Quality of life: the overall level of
respondents’ satisfaction with life and
particular life domains as evaluated
using Campbell’s subjective wellbeing scale [CAMPBELL 1976].
- Menopausal symptoms: 37 meno-
pausal symptoms classified in psychological/emotional (ESM), physical
(PSM) and sexual (SSM) categories
[HILDITCH and LEWIS 1996].
17
Biological age (BA) was defined and
computed using the procedure proposed
by BORKAN and NORRIS [1980a, 1986].
According to this approach, BA was
computed as a composite z-score. First,
the z-score was computed for a single
variable using formulas: either [(observed value – expected mean)/standard deviation] or [(observed value – expected
median)/the 1st-3rd quartile range] for
variables which were not distributed
normally in the population. The individual scores were converted to BA scores
by the three-step procedure: (1) simple
linear regression of each parameter on
age, (2) subtraction of the predicted score
from the individual scores, (3) standardization of the residual scores using
z-transformation. Profiles of BA were
then plotted on graphs whose abscissa
were in either positive or negative values of biological age and whose ordinates were the 23 study biomarkers units.
Negative values of the z-score referred
to biologically younger and positive
values of the z-score to biologically
older women compared to their peers.
To further evaluate significant differences between z-scores for sub-groups
based on study variables, the MannWhitney U-test was performed. All
computations were run using SPSS for
Windows, Version 12.0.
Results
Socio-demographic, health and lifestyle behavior characteristics are shown
in Table 1.
The studied women were between 46
and 73 years of age. The mean age was
57.4 years (SD 8.4 yrs). All women were
post natural menopause (postmenopausal
18
M. Kaczmarek, E. Lasik
Table 1. Selected characteristics of studied women (N = 461)
Characteristic
Mean
SD
Age (years)
BMI (kg/m2)
WHR (waist to hip ratio) (cm)
Weight (kg)
Height (cm)
Systolic Blood Pressure (mmHg)
Diastolic Blood Pressure (mmHg)
Mean Arterial Pressure (mmHg)
Haemoglobin (mmol/l)
Glucose (mol/l)
Erythrocyte Sedimentation Rate (mm/h)
Red Blood Cells (mln/mm3)
Total cholesterol (mmol/l)
Electrolytes: sodium (Na) (mmol/l)
Electrolytes: potassium (K) (mmol/l)
Total protein (g/dl)
Circumference: waist (cm)
Circumference: hip (cm)
Circumference: forearm (cm)
Circumference: breast (cm)
Emotional Menopausal Symptoms
Physical Menopausal Symptoms
Sexual Menopausal Symptoms
57.4
27.1
0.83
71.7
162.6
133.0
84.6
100.7
8.3
5.5
19.5
4.6
5.6
139.8
4.3
7.4
89.3
106.5
32.0
107.0
13.1
26.5
6.2
8.4
4.4
0.9
11.9
6.1
22.9
14.4
14.3
0.9
1.7
23.2
0.6
1.2
5.4
0.5
0.7
15.2
10.7
5.3
11.6
2.3
4.2
1.8
N
%
319
25
92
25
98
244
119
233
163
65
122
213
126
142
110
395
35
31
320
141
15.5
69.3
5.4
19.9
5.4
21.3
52.9
25.8
50.5
35.3
14.2
26.5
46.2
27.3
30.8
23.8
85.7
7.6
6.7
69.4
30.6
7.2
Marital status
Residence
Education
Self-rated health status
– married/partnered
– never married
– widowed
– divorced/separated
– village
– towns (pop. 20-500 thous)
– cities (pop. > 500 thous)
– primary/vocational
– secondary
– high (with academic degree)
– poor
– fair
– good
Alcohol consumption (yes)
Physical activity (yes)
HRT use
– never
– past
– current
Smoking status
– never smoked
– current smoker
– no of cigarettes per day (mean, SD)
Correlates of biological age in postmenopausal life
status). The mean recalled age at LMP
was 49.0 years (SD 4.5 yrs). The majority of studied women were from an urban
population (78.7%), married/partnered
(69.3%) or widowed (19.9%) at the time
of the survey, and had low level of educational attainment (50.5%). The reproductive history characteristics in the
study sample were as follows: mean
recalled age at menarche was 14.1 years
(SD 1.7 yrs) and age at first childbirth
23.3 years (SD 4.0 yrs). Among study
women, 42.6% had two children, 30.6%
were current smokers, 85.7% had never
used hormones, 30.8% preferred alcoholic drinks during social meetings,
27.3% self-rated their health status as
“good”, 23.8% reported physical activity of at least 1 hour/week. Among the
studied women, 41.7% were overweight
and 25.5% obese.
The biological age profiles by marital status, residence and educational
attainment are presented in Fig. 1. Generally, married/partnered women were
likely to be biologically younger than
their non-partnered (including never
married, separated and divorced) peers.
The z-score values of almost all study
variables were lower in married/partnered women compared to their single
peers. Statistically significant differences between married and single women
were found in potassium (p < 0.05),
emotional (p < 0.05), physical (p < 0.05),
and sexual menopausal symptoms
(p < 0.01), and quality of life (p < 0.01).
Married women were significantly older
than their single peers in relation to
menopausal symptoms.
Considering their living environment,
it was found that urban women were
likely to be biologically younger than
19
their rural peers. Of 23 variables studied, 7 revealed statistically significant
differences: systolic (p < 0.01) and diastolic blood pressure (p < 0.05), mean
arterial pressure (p < 0.01), weight
(p < 0.01), BMI (p < 0.01), quality of
life (p < 0.01), and physical menopausal
symptoms (p < 0.05). Women with high
educational attainment were likely to be
biologically younger than their poorly
educated counterparts. They also revealed higher satisfaction with quality of
life (p < 0.01).
The biological age profiles, in relation to health are presented in Fig. 2.
Obese women were likely to be biologically older than their normal peers. The
two groups differed significantly in relation to systolic (p < 0.01) and diastolic
(p < 0.05) blood pressure, mean arterial
pressure (p < 0.01) and anthropometric
measurements (p < 0.01).
Past and current HRT users were
likely to be biologically younger than
their counterparts, although a significant
difference was found only in relation to
quality of life (p < 0.05). Women who
rated their health as good/excellent were
biologically younger than their counterparts in all but anthropometric measurements.
Profiles of BA in relation to lifestyle
behavior characteristics are presented in
Fig. 3. Physical activity, nonsmoking
and non-drinking of alcohol were not
markedly associated with a younger BA
profile. Physically active women significantly differ from their physically
passive peers only in subjective perception of satisfaction with life. Women
who had never smoked were significantly heavier and had a higher BMI
than their currently smoking peers.
-1,5
Systolic pressure *
poorly educated
Hip size
0,5
-0,5
0
-1
Hip size
PSMW
Waist Hip Ratio
QoL **
QoL **
*
Body Mass Index **
Breast size
Forearm size
SSMW
*
1
SSMW
1,5
ESMW
urban environment (above 500 thous.)
ESMW
PSMW
Waist Hip Ratio
Body Mass Index **
Breast size
Forearm size *
Waist size
Height
Weight **
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
single
Waist size *
Height
Weight **
rural environment
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin *
Sodium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure **
Systolic pressure
*
*
*
QoL **
SSMW **
ESMW
PSMW
Waist Hip Ratio
Body Mass Index
Breast size
Forearm size
Hip size
Waist size
Height
Weight
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
Diastolic pressure
-2,5
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
Diastolic pressure *
Systolic pressure **
1
0,8
0,6
0,4
0,2
0
-0,2
-0,4
-0,6
-0,8
-1
Diastolic pressure
20
M. Kaczmarek, E. Lasik
0,5
1
-0,5
0
-1,5
-1
-2
married
w ell-educated
Fig. 1. Profiles of biological age in postmenopausal women by marital status, residence and educational attainment (statistically significant differences, U Mann-Whitney test, indicated by asterisks)
Systolic pressure
poor health
Hip size
-2
0
-1,5
-1
Systolic pressure **
Forearm size
Hip size **
Waist size **
Height
Weight **
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure **
Diastolic pressure *
QoL **
SSMW
Body Mass Index
Breast size
QoL *
QoL
PSMW
SSMW
-0,5
ESMW
1
SSMW
0,5
ESMW
1,5
ESMW
Hrt (past/current users)
Waist Hip Ratio **
-2
PSMW
-1
Waist Hip Ratio
-1,5
PSMW
0
Waist Hip Ratio
-0,5
Breast size *
1
Body Mass Index **
0,5
Breast size
*
Hip size
Forearm size
obesity I-III
Body Mass Index
Forearm size
Waist size
Height
Weight
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
normal w eight
Waist size
Hrt (never users)
Height
Weight
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
Systolic pressure
Diastolic pressure
-1,5
Diastolic pressure
Correlates of biological age in postmenopausal life
21
1,5
2
0,5
1
-0,5
0
-1
excellent health
Fig. 2. Profiles of biological age in postmenopausal women by BMI, use of HRT, self-rated health
status (statistically significant differences, U Mann-Whitney test, indicated by asterisks)
Systolic pressure
*
no alcohol
Hip size
Hip size
PSMW
ESMW
SSMW
Waist Hip Ratio
PSMW
ESMW
SSMW
QoL
Waist Hip Ratio
PSMW
ESMW
SSMW
QoL
2,5
2
1,5
1
0,5
0
-0,5
-1
-1,5
-2
-2,5
QoL **
Waist Hip Ratio
Body Mass Index
Breast size
Forearm size
Hip size
Waist size
Height
Weight
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
Breast size
**
Systolic pressure
Diastolic pressure
Body Mass Index
nonsmokers
Breast size
Forearm size
high physical activity
Body Mass Index
Forearm size
smokers
Waist size
Height
Weight **
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin
Sodium
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
passive physical activity
Waist size
Height
Systolic pressure
Diastolic pressure
1
0,8
0,6
0,4
0,2
0
-0,2
-0,4
-0,6
-0,8
-1
Weight
Erythrocyte sedimentation rate
Erythrocytes
Haemoglobin *
Sodium
0,8
0,6
0,4
0,2
0
-0,2
-0,4
-0,6
-0,8
-1
-1,2
Potassium
Total protein
Glucose
Total cholesterol
Mean Arterial pressure
Diastolic pressure
22
M. Kaczmarek, E. Lasik
alcohol
Fig. 3. Profiles of biological age in postmenopausal women by physical activity, smoking habit and
alcohol consumption (statistically significant differences, U Mann-Whitney test, indicated by asterisks)
Correlates of biological age in postmenopausal life
Discussion
This study has evaluated socio-demographic and lifestyle factors associated
with younger biological age in postreproductive life. Living environment,
educational attainment and marital status
appeared to be negatively associated
with biological age. The higher the urbanization category, educational level,
and married/partnered status, the younger
the biological age. Women who positively rated their health, used HRT, and
had a normal BMI were likely to be
biologically younger than their counterparts. Lifestyle behavior characteristics
such as physical activity, smoking of
cigarettes and alcohol consumption appeared to be weakly associated with BA
profiles of postmenopausal women.
The finding for Polish women that
indicates higher educational attainment
to be associated with younger biological
age is consistent with the results of
BORKAN and NORRIS [1980b, 1986].
They have also claimed that better educated male participants in their studies
are biologically younger than their
poorly educated peers. The education
factor is of arguable etiologic significance as it is rather a surrogate for other
exposures which may have direct physiological effects on aging women, such
as reproductive health. Women with
higher levels of education are likely to
have fewer children and later menopause than their poorly educated peers.
A low level of education is found to be a
risk factor for early menopause [LUOTO
et al. 1994, KACZMAREK in press].
It is claimed that educational attainment is associated with urbanization
category. Urban women are likely to reach
23
a higher level of education than their
rural counterparts. It has been suggested
that the joint effect of education and
urbanization is related to health through
health-related behaviors, or access to
health and medical care [SZKLARSKA
and ROGUCKA 2001]. In addition, a
selection mechanism has been hypothesized whereby poor health depresses
upward social mobility [VAN DE MHEEN
1999, BROESE VAN GROENOU 2003,
CARDANO et al. 2004]. The association
of positively perceived health with
younger biological age, as found in the
present study, is consistent with results
obtained by FURUKAWA et al. [1975]
and WEBSTER and LOGIE [1976]. However, in Poland, perceived health status
seems to be a weaker predictor of biological age than social class based on
education [SZKLARSKA and ROGUCKA
2001, and present data].
In the present study, past and/or current users of HRT appeared to be biologically younger than their counterparts. This finding corroborates well
with another study indicating the beneficial effect of HRT use on younger biological age and higher perceived health
status [DINGER et al. 2006]. This study
has demonstrated that women with normal BMI are likely to be biologically
younger, perhaps through protection
against the metabolic syndrome risk profile. The metabolic syndrome comprises
cardiovascular disease, hypertension, diabetes mellitus, hypercholesterinemia and
hyperinsulinemia [MATTHEWS et al. 2001].
Another finding of the present study
is that physical activity, smoking cigarettes and drinking of alcohol do not
clearly differentiate BA profiles. Further
research is needed to verify this finding
24
M. Kaczmarek, E. Lasik
as it is contrary to IGUCHI et al. [1996]
who found that managers nonsmoking
and drinking a moderate amount of
alcohol appeared to be biologically
younger than their counterparts. BULPITT et al. [1994] have observed that the
biological age of women who had
ceased smoking is 1-4 months younger
than their counterparts. Smoking has
been the most consistently noted influence on age at menopause in numerous
studies. KINNEY et al. [2006] has demonstrated that menopause occurs about
two years later among women who had
previously drunk alcohol 5-7 days per
week and two years earlier among those
who smoke 15 cigarettes per day. Considering that smoking may increase the
risk for earlier menopause and thereby
to various chronic diseases, further research is urgently needed.
In conclusion, it should be emphasized
that knowledge about the biological
status of postmenopausal women and
evaluation of factors associated with
younger biological age may help women
to succeed in dealing with diseases and
disability in the later stages of life. Further investigations are needed to determine the possible role of reproductive
lifespan characteristics on the individual’s rate of aging and to clarify some
inconclusive points in the present study.
Acknowledgements
We are grateful to Professor Anthony
Warnes, Sheffield Institute for Studies
on Ageing, University of Sheffield, UK
for stimulating discussion on various
aspects of human ageing and providing
access to the package of statistical
programs, SPSS for Windows, Version
12.0. We would also like to thank the
referees for valuable comments.
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Series No. 866
Streszczenie
Celem pracy była ocena czynników powiązanych z wiekiem biologicznym kobiet w fazie
życia po menopauzie naturalnej. Posłużono się koncepcją wieku biologicznego zaproponowaną przez Borkana i Morrisa w 1980 roku. Wiek biologiczny wyznaczono na podstawie 23
biomarkerów obejmujących charakterystyki układu krążenia, biochemiczne, hematologiczne,
pomiary antropometryczne, jakości życia i symptomów menopauzalnych. Posługując się
formułą [(wartość obserwowana – średnia artmetyczna) / odchylenie standardowe] lub
[(wartość obserwowana – mediana) / odległość kwartylowa] dokonano z przekształcenia,
najpierw dla każdej charakterystyki oddzielnie, następnie dla wszystkich 23 biomarkerów
łącznie. Wykreślono profile wieku biologicznego dla wybranych kategorii czynników społeczno-demograficznych. Wyznaczono dwie kategorie wieku biologicznego: młodszy (ujemne wartości) i starszy (dodatnie wartości) od przeciętnego charakterystycznego dla kobiet po
menopauzie.
Oceny dokonano w próbie liczącej 461 kobiet po menopauzie naturalnej, wybranej z bazy danych projektu badań kobiet w średnim wieku, prowadzonych w Polsce, w latach 20002004. Wiek badanych kobiet wynosił od 46 do 73 lat (średnia wieku 57,4; s = 8,4 lat). Charakterystykę próby przedstawiono w tabeli 1. Na ryc. 1 przedstawiono profile wieku biologicznego w zależności od czynników demograficznych i społecznych. Z obliczeń wieku
biologicznego wynika, że kobiety posiadające aktualnie partnera (zamężne lub w kohabitacji), zamieszkujące środowisko miejskie i wykształcone w stopniu wyższym były biologicz-
26
M. Kaczmarek, E. Lasik
nie młodsze od kobiet samotnych (nigdy niezamężne, wdowy, rozwiedzione, w separacji),
mieszkających na wsi i słabo wykształconych.
Na ryc. 2 przedstawiono profile wieku biologicznego wyznaczone dla kobiet o różnym
stanie zdrowia. Kobiety z BMI w normie, pozytywnie oceniające własne zdrowie oraz stosujące hormonalną terapię, były biologicznie młodsze od kobiet otyłych, źle oceniających
własne zdrowie i nigdy nie stosujących wspomagania hormonalnego. Na ryc. 3 przedstawiono profile wieku biologicznego w zależności od stylu życia: palenia papierosów, picia alkoholu i aktywności fizycznej. Trudno wskazać jednoznacznie, które kategorie zmiennych
stylu życia są powiązane z młodszym wiekiem biologicznym kobiet. W podsumowaniu należy stwierdzić, że wiedza o czynnikach powiązanych ze stanem biologicznym starzejących się
kobiet jest ważna dla podejmowania działań zmierzających do zapewnienia odpowiedniej
jakości życia w późnej i schyłkowej fazie.