RESEARCH ARTICLE Open Access
P e alence and incidence o cogni i e
impai men in an elde Po uguese
popula ion (65–85 yea s old)
Rica do Pais
1,2,3*
, Luís Ruano
1,2,4
, Ca la Mo ei a
1,2
, O élia P. Ca alho
1,2
and Hen ique Ba os
1,2
Abs ac
Backg ound: The inc ease in a e age li e expec ancy inc eases he isk o illness and ail y in he elde ly, especially
in he cogni i e a ena. This s udy has he objec i e o es ima e he p e alence and incidence o cogni i e
impai men , in a ep esen a i e sample o 65 o 85 yea s old ollowed o a mean pe iod o 6-yea s.
Me hods: Subjec s aged 65–85 yea s (n= 586) we e sc eened a baseline (1999–2004) o es ima e he p e alence o
cogni i e impai men using he Mini-Men al S a e Examina ion. A o al o 287 indi iduals wi h a no mal MMSE a
baseline we e eassessed a e 6.2 mean yea s (± 4.30 yea s) o e alua e he incidence o cogni i e impai men ,
de ined as sco ing below he age and educa ion-adjus ed MMSE cu -o poin s adap ed o he Po uguese
popula ion. We did no exclude Demen ia.
Resul s: The baseline p e alence o cogni i e impai men was 15.5% (95% CI: 12.7–18.7). Highe in women (18.9%;
95% CI: 14.9–23.3), ha in men (10.4%; 95% CI: 6.7–15.1). Inc eased wi h age and was highes o pa icipan s wi hou any
schooling. The o e all incidence a e was 26.97 pe 1000 pe son-yea s; highe in women (33.8 pe 1000 pe son-yea s) han
in men (18.0 pe 1000 pe son-yea s). Highe o he oldes pa icipan s and hose wi h no schooling. Taking he s anda d
Eu opean popula ion, we es ima ed a p e alence o 16.5% and an incidence o 34.4 pe 1000 pe son-yea s.
Conclusion: The p e alence o cogni i e impai men in Po ugal is wi hin he es ima ed in e al o he Eu opean
popula ion, and he incidence is lowe han o he majo i y o he Eu opean coun ies. Women, senio and elde s
wi hou educa ion ha e a highe isk o cogni i e impai men . In ou sample, nei he employmen no ma i al s a us has a
signi ican e ec on cogni i e impai men .
Keywo ds: Cogni i e impai men , P e alence, Incidence, Popula ion-based coho , EPIPo o
Backg ound
The ageing o he wo ld popula ion is a demog aphic end
ha will in ensi y in he coming decades. Eu os a p ojec s
ha by 2050 Po ugal will be he Eu opean coun y wi h
he highes pe cen age o people aged 55 yea s o mo e
(47%) [1]. The g owing numbe o olde people poses
heal h challenges such as inc easing he p e alence o dis-
ease and disabili y in he elde s, especially he bu den o
cogni i e dys unc ions [2]. Cogni i e impai men inc eases
he isko demen iaandmo ali yin heelde s[3,4]. I is
cha ac e ised by indi iduals ha ing mo e di icul ies wi h
memo y, lea ning, and he abili y o ocus on a ask, han
wouldbeno mallyexpec ed o heindi idual’sageand
educa ional le el [5]. I anges om mild de ici s ha a e
no clinically de ec able o demen ia [5]. I has a social im-
pac and is associa ed wi h o he pa hologies, such as
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* Co espondence: pais. ica [email protected]
1
EPIUni - Ins i u o de Saúde Pública, Uni e sidade do Po o, Rua das Taipas,
n° 135, 4050-600 Po o, Po ugal
2
Depa amen o de Epidemiologia Clínica, Medicina P edi i a e Saúde Pública,
Faculdade de Medicina da Uni e sidade do Po o, Alameda P o . He nâni
Mon ei o, 4200-319 Po o, Po ugal
Full lis o au ho in o ma ion is a ailable a he end o he a icle
Pais e al. BMC Ge ia ics (2020) 20:470
h ps://doi.o g/10.1186/s12877-020-01863-7
Alzheime o Demen ia [6,7]. Age, sex and le el o educa-
ion a e conside ed isk ac o s o cogni i e impai men
[4]. Con inued p o essional ac i i ies may be p o ec i e
agains cogni i e decline [8] howe e he e is a lack o in-
o ma ion abou he impac on cogni i e unc ion o pos -
ponemen o e i emen age. Also, changing demog aphics
cha ac e is ics added o a highe di o ce a e inc eases he
numbe o olde people li ing alone, especially women,
which adi ionally al eady p esen ed wi h an inc eased isk
o cogni i e decline [1,9,10].
Repo s on he p e alence and incidence o cogni i e
impai men , as well as i s ela ion wi h como bidi ies
and sociodemog aphic ac o s, a e essen ial o public
heal h and clinical ca e policy. They a e necessa y o
allow p ima y and seconda y p e en ion measu es
wi hin he heal hca e sys em.
In Eu ope, published s udies epo he p e alence o
cogni i e impai men o be be ween 5.1 and 24.5% [11–
16], whe eas in No h Ame ica, he es ima ed cogni i e
impai men p e alence anges om 13.8 o 28.3% [17–
19]. In Eu ope epo s ha used he Mini-Men al S a e
Exam o cogni i e impai men e alua ion in samples
wi h he same age cha ac e is ics as ou s es ima ed cog-
ni i e impai men p e alence be ween 7.7 and 33.1%
[12,16,20]. The incidence o cogni i e impai men
anges om 56.5 o 76.8 pe 1000 pe son-yea s in Eu -
ope [16,20,21] and om 41.8 o 65.4 pe 1000 pe son-
yea s, in No h Ame ica [22–24] In Po ugal, p e iously
published s udies epo a p e alence o cogni i e im-
pai men anging om 9.3 o 12.0% [10,25,26] and as
a as we know, he incidence is unknown.
Me hods
Aim
This s udy aims o es ima e he p e alence and inci-
dence o cogni i e impai men a e 6.2 mean yea ’s
ollow-up assessed using he Mini-Men al S a e Exam
(MMSE) in a coho o ci y dwelle s om Po o,
Po ugal, aged 65 o 85 yea s old, and o e alua e he im-
pac o age, sex, schooling, e i emen and ci il s a us in
cogni i e unc ion. Fo he main a iables o in e es , we
hypo hesize ha cogni i e impai men p e alence and
incidence a e simila o o he Eu opean coun ies.
S udy popula ion
The EPIPo o coho s udy design and me hodology
ha e been published p e iously [27,28]. In b ie , be-
ween 1999 and 2004, we assembled a ep esen a i e
sample o communi y dwelle s o Po o, an u ban cen e
in he no hwes o Po ugal, wi h app oxima ely 300,
000 inhabi an s a he ime. We selec ed Households by
andom digi dialling o landline elephones. Wi hin
each household, selec ed by simple andom sampling a
pe manen esiden aged 18 yea s o mo e and no
eplaced e usals. The p opo ion o pa icipa ion was
70%, and he inal sample size was 2485 indi iduals. O
he 633 pa icipan s wi h age be ween 65 and 85 yea s
old, 586 comple ed he assessmen a baseline. The
ollow-up e alua ion ook place in wo wa es, pa o he
pa icipan s (N= 221) we e e alua ed du ing he i s
ollow-up, be ween 2005 and 2008, and he o he s we e
e alua ed only on he second ollow-up (N= 66), be-
ween 2013 and 2015 (Fig. 1).
Da a collec ion and de ini ion o a iables
T ained in e iewe s pe o med a ace- o- ace ques ion-
nai e which collec ed da a on sociodemog aphic and be-
ha iou al cha ac e is ics [29] and adminis e ed he Mini-
Men al S a e Exam (MMSE) a he beginning o each
in e iew [30]. Educa ion was eco ded as comple ed
yea s o schooling and u he ca ego ized in o h ee
g oups: ze o yea s, one o 9 yea s and mo e han 10
yea s o schooling. Ci il s a us was ca ego ized in wo
g oups: ma ied o li ing oge he , and no -ma ied (di-
o ced, single o widowed). P o essional s a us was con-
side ed o be ei he wo king (pa icipan s employed),
e i ed (conside ing e i emen as a di ec ansi ion be-
ween a si ua ion o ull employmen and a si ua ion
whe e he indi idual is en i ely inac i e and whe e mos
o his esou ces consis o pension bene i s), o house-
wi es. The e we e no unemployed pa icipan s. Cogni-
i e impai men was e alua ed using he MMSE [30],
wi h cu -o poin s adjus ed by yea s o schooling ali-
da ed o he Po uguese popula ion: 22 o 0–2 yea s;
24 o 3–6 yea s and 27 o se en o mo e yea s o
schooling [31]. Subjec s wi h an MMSE sco e below he
age and educa ion adjus ed cu -o poin we e consid-
e ed o ha e cogni i e impai men . The MMSE is he
mos ci ed small-sized scale used o demen ia and cog-
ni i e impai men assessmen and is hough o be a eli-
able and alid es o cogni i e impai men [30,32].
P e alence e alua ion
A he baseline e alua ion, 633 pa icipan s we e aged 65
o 85 yea s old, bu we excluded 47 subjec s due o miss-
ing in o ma ion on he Mini-Men al S a e Exam
(MMSE). The inal sub-sample was 586 pa icipan s
(Table 1) wi h 71.95 yea s (± 4.84 SD) mean age; 355
we e women (60.6%); 57 (9.7%) had no educa ion, 432
(73.7%) had one o 9 yea s o educa ion, and 97 (16.6%)
had mo e han 10 yea s (16.6%) o schooling; 350
(59.7%) we e ma ied o li ing in ci il union; 464 (79.2)
we e e i ed.
Incidence e alua ion
The e we e wo ollow-up e alua ions whe e he pa ici-
pan s comple ed a ques ionnai e and had a physical
examina ion. The i s ollow-up was be ween 2005 and
Pais e al. BMC Ge ia ics (2020) 20:470 Page 2 o 10
Fig. 1 Flow-cha o pa icipan s h ough he s eps o he s udy and inal esul s on he equency o cogni i e impai men
Table 1 Socio-demog aphic cha ac e is ics o pa icipan s
Cha ac e is ic Baseline Follow-up Los o ollow-up P alue
N 586 287 208
Sex
Female 355 (60.6) 169 (58.9) 119 (57.2) 0.709
Male 231 (39.4) 118 (41.1) 89 (42.8)
Age (yea s)
[65–69] 216 (36.9) 125 (43.6) 67 (32.2) 0.010*
[70–74] 200 (34.1) 100 (34.8) 70 (33.7)
[75–79] 120 (20.5) 46 (16.0) 50 (24.0)
[80–85] 50 (8.5) 16 (5.6) 21 (10.1)
Educa ion
0 57 (9.7) 17 (5.9) 14 (6.7) 0.751
[1–9] 432 (73.7) 219 (76.3) 162 (77.9)
≥10 97 (16.6) 51 (17.8) 32 (15.4)
Ma i al S a us
Ma ied/Ci il Union 350 (59.7) 180 (62.7) 118 (56.7) 0.179
Single, di o ced, widowe 236 (40.3) 107 (37.3) 90 (43.3)
Employmen S a us
Wo k 50 (8.5) 26 (9.1) 18 (8.7) 0.626
Re i ed 464 (79.2) 233 (81.2) 164 (78.8)
Housewi es 71 (12.1) 28 (9.8) 26 (12.5)
Legend: Da a a e n(%); P- alue compa es ollow-up o los o ollow up, ob ained wi h Chi-squa e es
*Signi ican a p< 0.05
Pais e al. BMC Ge ia ics (2020) 20:470 Page 3 o 10
2008 and he second ollow-up be ween 2013 and 2015.
Some pa icipan s we e e alua ed only du ing he 1s o
he 2nd ollow-up. O he ini ial 586 eligible pa icipan s,
he e we e o e all 208 losses wi h 103 (49.5%) dea hs, 51
(24.5%) e usals, 26 (12.5%) we e no possible o con ac
and 28 (13.5%) missed wi hou jus i ica ion. We e-
e alua ed a o al o 287 pa icipan s (mean ollow-up o
6.2 yea s, SD 4.30 yea s). The e we e no signi ican di -
e ences ega ding sex, educa ion, ci il s a us o employ-
men s a us be ween ollow up pa icipan s and hose
los o ollow-up (Table 1). Howe e , pa icipan s los o
ollow-up we e olde (72.58 s 71.09 mean age in yea s).
Compe ing isk model
Du ing he ollow-up, in he disease/dea h p ocess, o en
mo e han one ype o e en plays a ole. We a e in e -
es ed as he i s e en a diagnosis o cogni i e impai -
men . Howe e , dea h may p e en he e en o in e es
om occu ing, because he pe son died be o e he diag-
nosis o cogni i e impai men . The e o e, dea h is a
compe ing isk o cogni i e impai men and may sub-
s an ially change he isk o disease diagnosis. Dea h
subs an ially educes he p obabili y o being diagnosed
wi h cogni i e impai men , and hence is ea ed as a
compe ing isk e en when calcula ing cogni i e impai -
men incidence [33,34]. Igno ing dea h as a compe ing
isk o ea i as no in o ma i e censo ed obse a ions
will lead o a bias in he s anda d me hods o es ima e
he p obabili y o he e en [35] such as he Kaplan-
Meie es ima e [36]. The assump ion o independence o
he ime o e en and he censo ing dis ibu ions is io-
la ed and hen iola es one o he undamen al assump-
ions o he Kaplan-Meie es ima o . We conside ed he
ime o e en as he ime om en e ing in he coho o
he i s e en , cogni i e impai men o dea h, du ing
he ollow-up.
The cumula i e incidence unc ion (CIF) allows o es-
ima ion o he incidence o he occu ence o an e en
while aking compe ing isk in o accoun [37,38]. This
allows one o es ima e incidence in a popula ion whe e
all compe ing e en s mus be accoun ed o in clinical
decision making. I deno es he p obabili y o expe ien-
cing he k h e en be o e ime and be o e he occu -
ence o a di e en ype o e en , i.e., o ins ance, he
p obabili y o expe ience dea h be o e 70 yea s old, be-
o e he occu ence o he cogni i e impai men . The
CIF has he desi able p ope y ha he sum o he CIF
es ima es o he incidence o each o he indi idual ou -
comes will equal he CIF es ima es o he incidence o
he composi e ou come consis ing o all o he compe -
ing e en s [39].
We pe o med he compe ing isks analysis o he 495
pa icipan s a isk o incidence o cogni i e impai men ,
excluding hose 105 ha e used o pa icipa e, missed
o we e impossible o con ac along all pe iod o he
ollow-up. F om hese 390, 103 died be o e cogni i e im-
pai men diagnosis, 48 we e diagnosed wi h cogni i e
impai men and 239 we e s ill ali e wi hou cogni i e
impai men diagnosis.
S a is ical analysis
We assessed di e ences in he p eposi ions using he
Chi-Squa e es . Losses o ollow-up we e compa ed o
pa icipan s in he ollow-up using he Chi-Squa e es .
Calcula ed c ude inciden a es di iding he numbe o
e en s by o al numbe o pe son-yea s a isk. Coun ed
ime a isk as he ime in yea s be ween he baseline
e alua ion and he las ollow-up ha each pa icipan
a ended and aking in o conside a ion he ull leng h o
ime o subjec s who emained ee o cogni i e impai -
men , and es ima e ime o onse o cogni i e impai -
men being se o he midpoin be ween he baseline
and ollow-up obse a ion wa es o hose pa icipan s
who did de elop he disease. Poisson gene alized linea
models we e used o de e mine con idence in e als,
wi h Log o ime a isk as o he o se . We es ed he
possible in e ac ion o each explana o y a iable wi h
age, sex, educa ion and e i emen s a us was es ed.
Sex-, age-, educa ion- and educa ion- adjus ed OR and
RR we e es ima ed. S anda dized p e alen and inciden
a es we e calcula ed o he Po uguese popula ion
using da a om he las census, in 2011 [40], and o
Eu opean popula ion using da a om he s anda d Eu o-
pean popula ion, 2013 [41]. The CIFs we e es ima ed in
R using he cuminc unc ion in he cmp sk R[42] pack-
age which uses he cumula i e incidence unc ion in o-
duced by Kalb leisch and P en ice [38].We used he
G ay’s es [43] o equali y o CIFs ac oss g oups. We
assessed di e ences in he MMSE mean sco e educ ion
o pa icipan s wi h and wi hou cogni i e impai men
wi h T- es o independen samples. The emaining
s a is ical analyses we e pe o med using SPSS® e sion
21. We include he Box Plo o he Mini-Men al S a e
Examina ion sco e o he popula ion a baseline e alu-
a ion and o he pa icipan s wi h o wi hou cogni i e
impai men a he ollow-up e alua ion as Supplemen-
a y ma e ial (Figu e S1).
Resul s
P e alence e alua ion
The c ude p e alence o cogni i e impai men was
15.5% (95% CI: 12.7–18.7) a baseline. The s anda dized
p e alence a e o he Po uguese popula ion was 16.9%
and o he s anda d Eu opean popula ion was 16.5%.
P e alence was lowe in men (10.4%; 95% CI: 6.7–15.1)
han in women (18.9; 95% CI: 14.9–23.3), wi h he odds
o p esen ing cogni i e impai men , adjus ed o age and
educa ion, o 0.95 (95% CI: 0.89–1.01).
Pais e al. BMC Ge ia ics (2020) 20:470 Page 4 o 10
The p e alence o cogni i e impai men inc eases wi h
age, being highe a 80–85 yea s han 65–69 yea s (26.0;
95% CI: 17.3–40.2 s 11.1; 95% CI: 9.3–17.2), wi h he
odds o cogni i e impai men , adjus ed o sex and edu-
ca ion, being 1.14 highe .
The cogni i e impai men p e alence is highe o pa -
icipan s wi h ze o yea s o schooling (45.6; 95% CI:
32.4–59.3) and sligh ly highe o pa icipan s wi h mo e
han 10 yea s han o pa icipan s wi h one o 9 yea s
(14.4; 95% CI 8.1–23.0 s 11.8; 95% CI 8.9–15.2) wi h
s a is ically signi ican di e ences.
No -ma ied pa icipan s had a highe p e alence o
cogni i e impai men (16.5; 95% CI: 12.0–21.9 s 14.9;
95% CI: 11.3–19.0), bu he di e ence was no s a is i-
cally signi ican a e adjus men o age and educa ion.
Re i ed pa icipan s had a highe p e alence o cogni i e
impai men han he wo king pa icipan s (14.4; 95% CI:
11.4–18.0 s 12.0; 95% CI: 4.6–24.3) and housewi es ha e
he highes p e alence (23.9; 95% CI: 14.6–35.5) bu wi h-
ou s a is ically signi ican di e ences. (Table 2).
Incidence e alua ion
Du ing he s udy p o ocol, 48 indi iduals de eloped cog-
ni i e impai men , an incidence a e o 26.97 pe 1000
pe son-yea s (95% CI: 20.3–35.8). The s anda dized inci-
dence a e using he Po uguese popula ion was 35.7 pe
1000 pe son-yea s and using he s anda d Eu opean
popula ion was 34.4 pe 1000 pe son-yea s.
The incidence o cogni i e impai men was highe in
women (33.8 pe 1000 pe son-yea s; 95% CI: 24.2–47.4)
han men (18.0 pe 1000 pe son-yea s; 95% CI: 10.7–30.5)
and inc easing wi h age a 80–85 yea s old (66.0 pe 1000
pe son-yea s; 95% CI: 27.5–158.7) s 65–69 yea s old
(21.1 pe 1000 pe son-yea s; 95% CI: 13.5–33.1).
As obse ed on baseline p e alence, he incidence is
highe o pa icipan s wi h ze o yea s o schooling
(126.4; 95% CI: 68.0–234.8) and almos he same o pa -
icipan s wi h 1 o 9 yea s and mo e han 10 yea s (21.6;
95% CI: 15.0–31.0 s 25.3; 95% CI 13.2–48.7).
No ma ied pa icipan s ha e a highe incidence a e
o cogni i e impai men (32.5; 95% CI: 21.4–49.4 s
23.6; 95% CI: 16.1–34.6), bu he di e ence did no e-
eal s a is ically signi ican di e ences a e adjus ing o
age and educa ion.
Re i ed pa icipan s ha e a highe incidence o cogni-
i e impai men han wo king pa icipan s (30.0; 95% CI:
21.3–37.9 s 18.1; 95% CI: 6.8–48.3) bu wi hou s a is i-
cally signi ican di e ences. (Table 3).
Table 2 Obse ed p e alence o cogni i e impai men by socio-demog aphic cha ac e is ics
Cha ac e is ics n P e . % (95% CI) p- alue OR (95% CI) Adjus ed
Sex
Female 67 18.9 (14.9–23.3) 0.006* 1 [ e e ence]
a
Male 24 10.4 (6.7–15.1) 0.95 (0.89–1.01)
Age (yea s)
[65–69] 24 11.1 (9.3–17.2) 0.026* 1 [ e e ence]
b
[70–74] 30 15.0 (11.0–21.1) 1.03 (0.97–1.10)
[75–79] 24 20.0 (13.3–28.3) 1.10 (1.02–1.19)
[80–85] 13 26.0 (17.3–40.2) 1.14 (1.03–1.27)
Educa ion
0 26 45.6 (32.4–59.3) 0.000* 1 [ e e ence]
c
[1–9] 51 11.8 (8.9–15.2) 0.72 (0.66–0.80)
≥10 14 14.4 (8.1–23.0) 0.74 (0.67–0.84)
Ma i al S a us
Ma ied/Ci il Union 52 14.9 (11.3–19.0) 0.584 1 [ e e ence]
d
Single, di o ced, widowe 39 16.5 (12.0–21.9) 0.96 (0.90–1.02)
Employmen S a us
Wo k 6 12.0 (4.6–24.3) 0.471 1 [ e e ence]
a
Re i ed 67 14.4 (11.4–18.0) 99.6 (0.90–1.10)
Housewi es 17 23.9 (14.6–35.5) 1.07 (0.94–1.22)
Legend: P e P e alence, OR odds a io. 95% CI: 95% con idence in e al
a
adjus ed o age and educa ion
b
adjus ed o sex and educa ion
c
adjus ed o sex and age
d
adjus ed o sex, age and educa ion
* Signi ican a p< 0.05
Pais e al. BMC Ge ia ics (2020) 20:470 Page 5 o 10

The c ude cumula i e incidences o cogni i e impai -
men and dea h in he o e all sample a e desc ibed in
Fig. 2, along wi h he incidence o he composi e ou -
come o all-cause o ailu e (dea h o cogni i e impai -
men ). The cumula i e incidence o all-cause ailu e is
equal o he sum o he cumula i e incidences o he 2
cause-speci ic ailu es. Al hough he cumula i e inci-
dence o dea h be o e he cogni i e impai men
exceeded ha o cogni i e impai men diagnosis a each
poin in ime, he incidence o cogni i e impai men was
no negligible in his popula ion. In he g oup analysis
by sex, he cumula i e incidence cu es o women and
men we e s a is ically di e en o cogni i e impai men
be o e dea h (P- alue 0.0008), and o dea h be o e cog-
ni i e impai men (P- alue 0.0004). The es ima ed CIFs
o each cause o ailu e by sex displayed in Fig. 3p e-
sen ed no able di e ences. In women, om 73 yea s old
o 80 yea s old, he cumula i e incidence o cogni i e
impai men is highe ha i s compe i i e e en , while
o he men, he incidence o dea h be o e cogni i e im-
pai men is highe in all poin s in ime when compa ed
o he cogni i e impai men diagnosis, ollowing he
same end as when analysing he whole sample. The es-
ima es o dea h be o e cogni i e impai men diagnosis
Fig. 2 Cumula i e incidence unc ions. The solid line shows he
cumula i e incidence o cogni i e impai men . The do ed line
shows he compe ing isk e en , i.e. dea h occu ing p io o he
cogni i e impai men . The dashed line shows he cumula i e
incidence unc ion o all-cause ailu e, i.e. he sum o he cumula i e
incidences o he 2 cause-speci ic ailu es
Table 3 Obse ed incidence o cogni i e impai men by socio-demog aphic cha ac e is ics
Cha ac e is ics n Incidence (95% CI) pe 1000 pe son-yea s p- alue RR (95% CI) Adjus ed
Sex
Female 34 33.8 (24.2–47.4) 0.084 1 [ e e ence]
a
Male 14 18.0 (10.7–30.5) 0.66 (0.35–1.27)
Age (yea s)
[65–69] 19 21.1 (13.5–33.1) 0.142 1 [ e e ence]
b
[70–74] 16 25.8 (15.8–42.2) 1.29 (0.66–2.52)
[75–79] 8 43.5 (21.7–86.9) 2.20 (0.96–5.05)
[80–85] 5 66.0 (27.5–158.7) 2.01 (0.72–5.58)
Educa ion
0 10 126.4 (68.0–234.8) 0.005* 1 [ e e ence]
c
[1–9] 29 21.6 (15.0–31.0) 0.21 (0.10–0.47)
≥10 9 25.3 (13.2–48.7) 0.25 (0.10–0.65)
Ma i al S a us
Ma ied/Ci il Union 26 23.6 (16.1–34.6) 0.296 1 [ e e ence]
d
Single, di o ced, widowe 22 32.5 (21.4–49.4) 1.03 (0.55–1.93)
Employmen S a us
Wo k 4 18.1 (6.8–48.3) 0.911 1 [ e e ence]
a
Re i ed 40 30.0 (21.3–37.9) 1.30 (0.44–3.79)
Housewi es 4 22.3 (24.2–47.4) 0.79 (0.19–3.31)
Legend: RR ela i e isk. 95%, CI 95% con idence in e al
a
adjus ed o age and educa ion
b
adjus ed o educa ion and sex
c
adjus ed o age and sex
d
adjus ed o sex, age and educa ion
*Signi ican a p< 0.05
Pais e al. BMC Ge ia ics (2020) 20:470 Page 6 o 10
o he women exceeds he es ima es o cogni i e impai -
men diagnosis in he poin ’s ime a e 80 yea s old. The
slope o he cu es a e qui e simila in women and men
un il 70 yea s −75 yea s old, howe e , in he men i can
be obse ed a highe p obabili y o dea h be o e cogni-
i e impai men han in he women.
Pa icipan s wi h cogni i e impai men had an a e age
MMSE sco e educ ion o 5.33 (SD 3.64), while pa ici-
pan s wi hou cogni i e impai men had an a e age o
0.44 educ ion (SD = 1.84) (p= 0.000) o e he ime a
isk o 6.2 mean yea s (± 4.30 yea s).
Discussion
In his u ban popula ion wi h 65 o 85 yea s, he p e a-
lence o cogni i e impai men was 15.5%. I was highe
in women, in no -ma ied pa icipan s, and e i ed pa -
icipan s, i inc eased wi h age and dec eased wi h edu-
ca ion yea s.
P e ious s udies wi h Po uguese popula ion samples e-
po ed a p e alence o cogni i e impai men be ween 9.3
and 12.0% [10,25,26] using younge pa icipan s, o e 50
yea s old on he i s s udy and o e 55 yea s old on he
o he wo. Bo h he s udies which used he MMSE as a
sc eening es , Nunes e al. [25] and Ruano e al. [26]com-
plemen ed he esul s wi h a neu ologis e alua ion. I is
wo h o poin ou ha Ruano e al. [26] epo he 2015
p e alence o he EpiPo o coho wi h he p esen s udy
ocusing on he pe iod om 1999 o 2004 and ha only in
he cu en s udy was he incidence o cogni i e impai -
men in his popula ion asce ained (1999–2015).
The p e alence es ima e ound in ou s udy is wi hin
he es ima ed in e al o he Eu opean popula ion using
asce ainmen app oaches simila o ou s [9,20].
As p e iously epo ed cogni i e impai men p e alence
was highe in women han in men [9,10,44], wi h s udies
poin ing ou ho monal causes, namely he loss o es o-
gens in women, o jus i y his di e ence [45]. I inc eased
in equency wi h inc easing age be ween he ages o 65
and 85 yea s, which is in acco dance o o he s udies ha
associa ed ageing wi h cogni i e decline and demen ia [9,
10,44,46] and i is associa ed wi h low le els o educa ion,
possibly due o he highe cogni i e ese e o he ones
wi h mo e yea s o educa ion [9,44,47]. Pa icipan s wi h-
ou schooling ha e a highe p e alence o cogni i e im-
pai men han pa icipan s wi h a leas some schooling.
Pa icipan s wi h mo e han 10 yea s o schooling ha e a
highe p e alence o cogni i e impai men compa ed wi h
hose be ween one and 9 yea s o schooling. Howe e , his
may be a ibu able o hei highe mean age and p esence
o mo e pa icipan s wi h 80–85 yea s old (13.4% s 6.9%).
When we de e mined he odds a io, adjus ed o sex and
age, he isk is almos he same (0.72 s 0.74) be ween
bo h g oups and s a is ically di e en o he g oup wi h-
ou any schooling. I was also sligh ly highe o no -
ma ied pa icipan s [9,44,48] despi e no eaching s a is-
ical signi icance and we did no ind di e ences be ween
e i ed and non- e i ed pa icipan s (Table 2).
Fo 6.2 mean yea s o ollow-up ime, we obse ed ha
he incidence a e o cogni i e impai men was 26.97 pe
1000 pe son-yea s. The s anda dized inciden a e o
he Po uguese popula ion was 35.7 and o he s anda d
Eu opean popula ion was 34.4 pe 1000 pe son-yea s.
The cogni i e impai men incidence we ound in ou
sample is lowe han es ima es o o he Eu opean coun-
ies [20,21,49] and No h Ame ica, [22,23] howe e
his migh be due o he olde popula ions and di e en
cogni i e impai men de ini ions used in hese s udies.
Fig. 3 Cumula i e incidence unc ions by sex. Le panel: The solid line shows he cumula i e incidence o cogni i e impai men , o women.
Righ panel: The do ed line shows he compe ing isk e en , i.e. dea h occu ing p io o he cogni i e impai men , o Men
Pais e al. BMC Ge ia ics (2020) 20:470 Page 7 o 10
In conco dance wi h o he s udies [22,24,49,50], we
also obse ed a end owa ds inc eased incidence wi h
olde age, and highe in women albei wi hou eaching
s a is ical signi icance. These indings we e also achie ed
when conside ing dea h as a compe ing isk o cogni i e
impai men .
Pa icipan s wi h ze o yea s o schooling ha e a highe
incidence o cogni i e impai men han he ones wi h
schooling, which is in conco dance o he impac o edu-
ca ion yea s epo ed in p e ious indings [20,51].
Non-ma ied pa icipan s ha e a non-signi ican end
owa ds a highe incidence o cogni i e impai men ,
which could be explained by he memo y and cogni ion
s imula ion o he ma ied pa icipan s [52].. Fo em-
ploymen s a us, we obse e ha e i ed pa icipan s
ha e a end owa ds a highe incidence o cogni i e im-
pai men han he ones which a e s ill wo king, a e
adjus ing o age and educa ion, which may indica e a
p o ec i e e ec o wo king, as desc ibed be o e [8,53].
I would be in e es ing o conduc u he wo k o y o
de e mine i indeed wo king has a p o ec i e e ec on
cogni i e decline o i o he social dimensions in ol ed
in being employed media es his e ec .
The a e age MMSE sco e educ ion is highe in pa -
icipan s wi h cogni i e impai men compa ed wi h
o he pa icipan s, which demons a es a mo e p o-
nounced cogni i e loss on he i s ones ha mus be
aken in o accoun when de ining p e en i e measu es
in he Heal h Sys em.
A p e ious s udy [26] has ound ha one o he majo
causes o cogni i e impai men in his popula ion s ems
om ascula disease, as such we sugges ha help man-
aging blood p essu e and an inc ease in physical ac i i y,
i a ge ed o hese g oups, could lead o signi ican pub-
lic heal h imp o emen s.
In Po ugal, in he pe iod unde analysis, om 1999 o
2015, he demog aphic cha ac e is ics o he popula ion
o e 65 yea s old changed and, acco ding o PORDATA,
he pe cen age o olde people inc eased om 15.9 o
20.5% [54], and he numbe o people wi hou educa ion
dec eased by 36.7% and hose wi h highe educa ion, in-
c eased by 247.7% [55]. The inc eased educa ion may
ha e con ibu ed o he dec ease in he p e alence o
cogni i e impai men om 15.5 o 9.3% [26], despi e
some me hodological di e ences in he wo s udies in
he EpiPo o coho discussed abo e. The inc ease in
schooling will mi iga e he e ec o inc easing a e age
li e expec ancy, bu i should be aken o he measu es
because by 2050, Po ugal will be one o he Eu opean
coun ies wi h a highe pe cen age o olde people and
wi h he highes old-age dependency a io.
The main s eng hs o ou s udy a e he popula ion-
based coho and he long- e m p ospec i e s udy design
as well as he use o MMSE published cu -o poin s
adjus ed o educa ion. This s udy p o ides an es ima e
o he p e alence and incidence o cogni i e impai men
in an elde wes e n Eu opean coho p o iding essen ial
da a o a ge public heal h s a egies accu a ely.
Some me hodological limi a ions may ha e o e es ima ed
he esul s, namely he inabili y o diagnose demen ia,
meaning ha we could no exclude pa icipan s wi h de-
men ia om he s udy, which may ha e o e es ima ed he
p e alence o cogni i e impai men a baseline. Mo ali y as
a compe ing isk may ha e o e es ima ed he incidence o
cogni i e impai men . Pa icipan s los - o- ollow-up whe e
olde and wi h lowe mean MMSE sco es han he pa ici-
pan s and his could ha e unde es ima ed he incidence
calcula ions.
Conclusion
This s udy epo s a p e alence o cogni i e impai men
o 15.5% and an incidence o 26.97 pe 1000 pe son-
yea s in a coho o ci y dwelle s om Po o, Po ugal,
aged 65 o 85 yea s old. Women and elde s wi hou
schooling ha e a highe isk o de eloping cogni i e im-
pai men , and his isk inc eases wi h ageing. This s udy
highligh s he need o de elop p e en i e heal h mea-
su es a ge ed o hese g oups o help main ain b ain
heal h wi h ageing. In ou s udy we ound ha nei he
e i emen no ma i al s a us ha e a signi ican e ec on
cogni i e impai men .
Supplemen a y In o ma ion
The online e sion con ains supplemen a y ma e ial a ailable a h ps://doi.
o g/10.1186/s12877-020-01863-7.
Addi ional ile 1: Figu e S1. Box Plo o he Mini-Men al S a e Examin-
a ion sco e o he popula ion a baseline e alua ion and pa icipan s wi h
o wi hou cogni i e impai men a he ollow-up e alua ion.
Abb e ia ions
MMSE: Mini-Men al S a e Examina ion; CIF: Cumula i e incidence unc ion;
OR: Odds a io; RR: Rela i e Risk
Acknowledgemen s
No applicable.
Au ho s’con ibu ions
All au ho s con ibu ed o he s udy concep ion and design. Ma e ial
p epa a ion and da a collec ion: RP. S a is ical analysis: RP, CM. W i ing -
e iew and edi ing: RP, LR, CM, OC, HB. Supe ision: HB. RP w o e he i s
d a o he manusc ip and all au ho s commen ed on p e ious e sions o
he manusc ip . All au ho s ead and app o ed he inal manusc ip .
Funding
Fundo Eu opeu de Desen ol imen o Regional (FEDER), and he P og ama
Ope acional Compe i i idade e In e nacionalização (POCI) (POCI-01-0145-
FEDER-016867) o he Eu opean Union, and by he Fundação pa a a Ciência
e a Tecnologia, no âmbi o da Unidade de In es igação em Epidemiologia -
Ins i u o de Saúde Pública da Uni e sidade do Po o (EPIUni ) (POCI-01-0145-
FEDER-006862; Re .° FCT UID/DTP/04750/2013). The ole o unding body was
o unding EpiPo o Coho S udy.
Pais e al. BMC Ge ia ics (2020) 20:470 Page 8 o 10
A ailabili y o da a and ma e ials
The da ase s used and analysed du ing he cu en s udy a e a ailable om
he co esponding au ho on easonable eques .
E hics app o al and consen o pa icipa e
All p ocedu es pe o med in s udies in ol ing human pa icipan s we e in
ag eemen wi h he e hical s anda ds o he ins i u ional and na ional
esea ch commi ee and wi h he 1964 Helsinki decla a ion and i s la e
amendmen s o compa able e hical s anda ds. The e hics commi ee o
Hospi al de São João app o ed he s udy. All indi idual pa icipan s ecei ed
an explana ion on he pu pose and design o he s udy and ga e hei
w i en in o med consen in he e alua ion. In pa icipan s wi h cogni i e
impai men , w i en consen was also sough om a alid su oga e.
Consen o publica ion
No Applicable.
Compe ing in e es s
The au ho s decla e ha hey ha e no compe ing o in e es and ce i y
esponsibili y o he manusc ip .
Au ho de ails
1
EPIUni - Ins i u o de Saúde Pública, Uni e sidade do Po o, Rua das Taipas,
n° 135, 4050-600 Po o, Po ugal.
2
Depa amen o de Epidemiologia Clínica,
Medicina P edi i a e Saúde Pública, Faculdade de Medicina da Uni e sidade
do Po o, Alameda P o . He nâni Mon ei o, 4200-319 Po o, Po ugal.
3
Unidade de Saúde Familia Lusi ana, A . An ónio José Almeida, 3514-511
Viseu, Po ugal.
4
Depa amen o de Neu ologia, Hospi al de São Sebas ião,
Cen o Hospi ala de En e o Dou o e Vouga, Rua Cândido Pinho, 4520-211
San a Ma ia da Fei a, Po ugal.
Recei ed: 8 July 2020 Accep ed: 31 Oc obe 2020
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