title: Distinct Patterns of Cognitive Aging Modified by Education Level and Gender among Adults with Limited or No Formal Education: A Normative Study of the Mini-Mental State Examination.
abstract: BACKGROUND
  Dementia is increasingly prevalent due to rapid aging of the population, but under-recognized among people with low education levels. This is partly due to a lack of appropriate and precise normative data, which underestimates cognitive aging in the use of screening tools for dementia.
  
  
  OBJECTIVE
  We aimed to improve the precision of screening for cognitive impairment, by characterizing the patterns of cognitive aging and derived normative data of the Mini-Mental State Examination (MMSE) for illiterate and low-educated populations.
  
  
  METHODS
  This community-based study included data from 2,280 individuals aged 40 years or older from two rural areas. Multiple linear modeling examined the effect of aging on cognition reflected by the MMSE, stratified by education level and gender. Threshold effect of age on cognition was performed using a smoothing function.
  
  
  RESULTS
  The majority of participants (60.4%) were illiterate or had attended only primary school (24.6%). The effect of aging on cognition varied by gender and education. Primary-school educated females and males remained cognitively stable up to 62 and 71 years of age, respectively, with MMSE score declining 0.4 and 0.8 points/year in females and males thereafter. Illiterates females scored 2.3 points lower than illiterate males, and scores for both declined 0.2 points/year. According to these results, normative data stratified by age, education and gender was generated.
  
  
  CONCLUSIONS
  This study suggests gender and educational differences exist in cognitive aging among adults with limited or no formal education. To improve screening precision for cognitive impairment with the use of MMSE in low-educated population, age, gender, and education level should be considered.
authors.affiliation: Department of Neurology, Foshan Hospital Affiliated to Sun Yat-sen University, Foshan, Guangdong, China.
authors.forename: Haiqun
authors.initials: H
authors.lastname: Xie
authors.affiliation: Department of Neurology, Foshan Hospital Affiliated to Sun Yat-sen University, Foshan, Guangdong, China.
authors.forename: Chengguo
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Neurology, Foshan Hospital Affiliated to Sun Yat-sen University, Foshan, Guangdong, China.
authors.forename: Yukai
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Neurology, Foshan Hospital Affiliated to Sun Yat-sen University, Foshan, Guangdong, China.
authors.forename: Shuyun
authors.initials: S
authors.lastname: Huang
authors.affiliation: Institute of Biomedicine, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Cui
authors.affiliation: Institute of Biomedicine, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Yang
authors.affiliation: The Allan Memorial Institute, P2.142, McGill University Health Centre, Montréal, Quebec, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Koski
authors.affiliation: Division of Nephrology, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Xiping
authors.initials: X
authors.lastname: Xu
authors.affiliation: Division of Nephrology, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Youbao
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Cardiology, Beijing Chaoyang Hospital Affiliated to Capital University, Beijing, China.
authors.forename: Meili
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Department of Neurology, First People's Hospital, Lianyungang, Jiangsu, China.
authors.forename: Mingli
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Neurology, First Affiliated Hospital, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Neurology, First Affiliated Hospital, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Shi
authors.affiliation: Department of Neurology, First Affiliated Hospital, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.affiliation: Institute of Biomedicine, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Genfu
authors.initials: G
authors.lastname: Tang
authors.affiliation: Institute of Biomedicine, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Binyan
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Peking University First Hospital, Beijing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Huo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003072:Cognition Disorders / Q000175:diagnosis; D000066492:Cognitive Aging / Q000523:psychology; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D008875:Middle Aged; D012016:Reference Values; D012424:Rural Population; D012727:Sex Characteristics
keywords: Aging; MMSE; cognitive impairment; gender; norms