Richard J.Caselli, Professor of Neurology, Mayo Clinic Arizonacaselli.richard@mayo.edu
Submitted November 13, 2014
Johansson et al. described the influence of personality features and long-
standing distress on the risk of Alzheimer disease (AD) dementia that
remained significant after controlling for possession of the APOE e4
allele in a subset of 306 women with APOE genotyping. [1] The prevalence
of the APOE e4 allele in their cohort, which was described as
"systematically sampled from the Swedish Population Register", was only
11.3% (Table 1 [1]). There is a general north/ south gradient of
descending APOE e4 prevalence among European populations, and prevalence
estimates of the APOE e4 allele in Sweden were initially reported in 1995
and 1999 as 20.6% . [2] Studies of the Kungsholmen region of Stockholm
have subsequently reported an e4 prevalence rate of roughly 28%. [3,4]
The discrepancy in e4 prevalence rates suggests that the cohort in
Johansson et al.'s study was not actually representative of the Swedish
population. To fully understand the implications of their findings, the
authors should clarify how their cohort members were selected.
1. Johansson L, Guo X, Duberstein PR, et al.
Midlife personality and risk of Alzheimer disease and distress.
A 38-year followup. Neurology 2014; 83: 1538-1544.
2. Corbo RM, Scacchi R. Apolipoprotein E (APOE)
allele distribution in the world. Is APOE*4 a 'thrifty' allel? Ann Hum
Genet 1999; 63: 301- 310.
3. Ferrari C, Xu WL, Wang HX, et al. How can elderly
apolipoprotein E e4 carriers remain free from dementia? Neurobiol Aging
2013; 34: 13-21.
4. Welmer AK, Angleman S, Rydwik E, Fratiglioni L, Qiu
C. Association of cardiovascular burden with mobility limitation among
elderly people: a population based study. PLoS One 2013; 8: e65815.
For disclosures, contact the editorial office at
journal@neurology.org.
Johansson et al. described the influence of personality features and long- standing distress on the risk of Alzheimer disease (AD) dementia that remained significant after controlling for possession of the APOE e4 allele in a subset of 306 women with APOE genotyping. [1] The prevalence of the APOE e4 allele in their cohort, which was described as "systematically sampled from the Swedish Population Register", was only 11.3% (Table 1 [1]). There is a general north/ south gradient of descending APOE e4 prevalence among European populations, and prevalence estimates of the APOE e4 allele in Sweden were initially reported in 1995 and 1999 as 20.6% . [2] Studies of the Kungsholmen region of Stockholm have subsequently reported an e4 prevalence rate of roughly 28%. [3,4] The discrepancy in e4 prevalence rates suggests that the cohort in Johansson et al.'s study was not actually representative of the Swedish population. To fully understand the implications of their findings, the authors should clarify how their cohort members were selected.
1. Johansson L, Guo X, Duberstein PR, et al. Midlife personality and risk of Alzheimer disease and distress. A 38-year followup. Neurology 2014; 83: 1538-1544.
2. Corbo RM, Scacchi R. Apolipoprotein E (APOE) allele distribution in the world. Is APOE*4 a 'thrifty' allel? Ann Hum Genet 1999; 63: 301- 310.
3. Ferrari C, Xu WL, Wang HX, et al. How can elderly apolipoprotein E e4 carriers remain free from dementia? Neurobiol Aging 2013; 34: 13-21.
4. Welmer AK, Angleman S, Rydwik E, Fratiglioni L, Qiu C. Association of cardiovascular burden with mobility limitation among elderly people: a population based study. PLoS One 2013; 8: e65815.
For disclosures, contact the editorial office at journal@neurology.org.