A cognitive test score reflects more than memory: in the library's studies, age, years of education, APOE ε4 status, sex and mood are each linked to scores or to how fast they change. In a 2017 analysis of 14 cohorts and 42,170 people aged 54-105, performance on all cognitive measures declined with age, at a most rapid pooled rate of 0.26 standard deviations per decade.
What the studies found
A 2017 PLoS Medicine study harmonized longitudinal data for 14 cohorts from 12 countries, a total of 42,170 individuals aged 54-105. Performance on all cognitive measures declined with age, and more rapidly with increasing age, with the most rapid pooled rate of change 0.26 standard deviations per decade. The study also examined sex, educational attainment and APOE ε4 carrier status as factors associated with decline, and the authors report that associations varied across cohorts.
Education shifts the score itself. A 2015 study derived Montreal Cognitive Assessment norms from 205 participants aged 70-99, grouped by age (70-79, 80-89, 90-99) and by education (12 years or less, 13-15, 16 or more), and found significant differences between the groups, with younger and more educated participants outperforming the others. The authors note that the original validation cutoff of 26 may be too stringent for older adults, particularly those with less education.
The same pattern appeared on the Mini-Mental State exam. In a 1991 study of 100 white and 258 black individuals, people without dementia who had an 8th grade or less education had significantly worse total scores than the better educated, and 25% of the lower-education group scored in the 18-23 range traditionally thought to suggest dementia. There were no consistently significant differences between blacks and whites of equal education.
APOE ε4 is studied mainly as a predictor of decline in people who already have Alzheimer's. A 2008 Neurology study followed participants for an average of 4 years and found that at least one ε4 allele was associated with faster cognitive decline in the incident population-based Alzheimer's group (p = 0.01). The authors conclude that APOE ε4 may influence the rate of cognitive decline most significantly in the earliest stages of Alzheimer's disease.
On sex, a 2021 Lancet Public Health analysis of two UK-based prospective cohort studies (924 participants) concluded that decreasing disparities between sexes in education, due to secular increases in educational opportunities, could attenuate sex differences in dementia risk and cognitive decline in the future.
Mood is linked to the score on the day. In a 2006 prospective study of 1265 adults aged 67 and older without dementia, those among the 1094 who remained dementia free and had depressive symptoms at baseline had significantly lower baseline scores on all cognitive composites than the nondepressed participants, but depressive symptoms were not associated with the rate of cognitive decline over time in either group. A 2004 study of one hundred patients aged 60 and older with major depression and 40 nondepressed controls found that the patients performed poorer in all cognitive domains, and more than half exhibited significant impairment.
- Studies
- Depressive symptoms and cognitive decline in late life: a prospective epidemiological study
- The nature and determinants of neuropsychological functioning in late-life depression
What remains uncertain
Most of these records are observational, so they show association rather than cause, and the 2017 authors report that associations varied across cohorts. The APOE ε4 result comes from people already diagnosed with Alzheimer's, so it does not say what a given genotype means for someone whose score is in the normal range.
- Studies
- Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study
- APOE epsilon 4 allele predicts faster cognitive decline in mild Alzheimer disease
The records on mood do not fully agree. The 2006 study found no link between depressive symptoms and the rate of decline, while a 2014 study of 2425 older adults followed over 12 years found that initial depressive symptoms predicted accelerated memory decline and that memory scores did not predict later depressive symptoms. A score is one measurement, and a clinician who knows the person can say what it means for them.
- Studies
- Depressive symptoms and cognitive decline in late life: a prospective epidemiological study
- Depressive symptoms precede memory decline, but not vice versa, in non-demented older adults
This page describes what published studies in alzhub's library report. It is not medical advice and does not apply to any one person. Where a decision would follow, a clinician who knows the person is the one who can say what a result or a choice means for them.
Questions
- Does age change a cognitive test score?
- In a harmonized analysis of 14 cohorts and 42,170 people aged 54-105, performance on all cognitive measures declined with age, and more rapidly with increasing age. The most rapid pooled rate was 0.26 standard deviations per decade.
- Does education change a score on the MMSE or MoCA?
- In the records above it does: in a 1991 study, people with an 8th grade or less education had significantly worse Mini-Mental State scores than the better educated, and a 2015 study found that younger and more educated participants outperformed the others on the MoCA.
- Does carrying APOE ε4 lower a test score?
- The record in the library studies decline rather than a single score: in a 2008 study, at least one ε4 allele was associated with faster cognitive decline in the incident population-based Alzheimer's group (p = 0.01).
- Do men and women score differently?
- A 2021 analysis of two UK-based cohort studies concluded that decreasing disparities between sexes in education could attenuate sex differences in dementia risk and cognitive decline in the future.
- Can depression lower a memory test score?
- In a 2006 study, adults with depressive symptoms had significantly lower baseline scores on all cognitive composites than nondepressed participants, though the symptoms were not associated with the rate of cognitive decline over time.
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