Inheritance of the ApoE ε4 Allele Increases the Rate of Brain Atrophy in Dementia Patients

Abstract

We investigated the influence of the apolipoprotein (ApoE) ε4 allele on the rate of brain atrophy in patients with clinical dementia and in subjects at risk for dementia. Eighty-one subjects, consecutively referred to a memory clinic due to symptoms of dementia, went through a comprehensive examination, including cerebral magnetic resonance imaging. After an initial investigation these subjects were divided into one of six diagnostic groups; Alzheimer’s disease (AD, n = 23), objective cognitive impairment (OCI, n = 27), subjective cognitive impairment (SCI, n = 17), vascular dementia (VaD), frontotemporal dementia (FTD) and unspecified dementia (USD). The last three groups were joined into one diagnostic group designated ‘other dementia’ (OD, altogether n = 14). In order to study the progression of cognitive impairment as well as the rate of atrophy in different brain regions all subjects were reinvestigated after an average period of 16 monhts. Interest was focused on investigating if those subjects with one or two ε4 alleles differed in either dementia progression or rate of brain atrophy compared to those without the ε4 allele. We found that the ApoE ε4 carriers had a statistically significantly larger increase in ventricular volume as compared with the ApoE ε4 noncarriers. In all diagnostic groups the ApoE ε4 carriers showed a greater rate of ventricular volume increase, as compared to the noncarriers. However, this difference was statistically significant only for the OD subjects. No statistical significant changes over time were seen for whole brain volume or volume of the temporal lobes and the medial temporal lobes. The diagnostic groups differed in dementia progression with the AD subjects having the most pronounced reduction in MMSE scores as compared to subjects at risk for AD (OCI and SCI subjects). The presence of ApoE ε4 allele did not influence the change in MMSE in any of the diagnostic groups.