ApoE genotype and abnormal auditory cortical potentials in healthy older females

Abstract

Apolipoprotein E (ApoE) status and gender are risk factors for the development of Alzheimer's disease. Alzheimer's disease is more prevalent in female relative to male carriers of the ApoE 4 gene. We examined cortical sensory (P50, N100) and cognitive (P300) potentials in an auditory target detection task in females as a function of ApoE genotype (ApoE 4 carriers, ApoE 4 non-carriers) to define the incidence of abnormalities prior to the clinical expression of cognitive impairments. Both neuropsychological test scores and sensory cortical potentials did not differ between the two ApoE groups. In contrast, cognitive P300 potentials were significantly decreased in amplitude and delayed in latency for ApoE 4 carriers compared to non-carriers. Four out of the 10 ApoE 4 carriers had abnormally (>2S.D.) delayed P300 latency compared to one out of 20 non-carriers. Abnormal cognitive processes reflected by P300 latency delays are expressed at significantly higher incidence in normal older females who are carriers of the 4 allele than in non-carriers of this allele.

Apolipoprotein E4 and Sex Affect Neurobehavioral Performance in Primary School Children

“…In addition, during the visible learning trials of Memory Island, there was a genotype × sex interaction. With the heightened sensitivities of females to the consequences of apoE4 (11,38), these findings highlight the importance for future investigations to carefully monitor for apoE by sex interactions or to continue examining females separately (37,39). Sex differences, independent of apoE4, were also identified in the spatial learning trials of Memory Island with boys showing greater velocity and reaching the target sooner than girls, consistent with faster and more accurate performance by males than females in virtual water mazes across the lifespan (13,33,40,41).…”

P50: A candidate ERP biomarker of prodromal Alzheimer׳s disease

“…Methodological differences complicate comparison across studies; however, studies that failed to show significantly larger P50 amplitudes in AD patients relative to those from age-matched controls have included a more severe cohort in the mild-to-moderate AD range (e.g., MMSE = 13.2±5.4) (Golob et al, 2007) than in the very mild range (e.g, MMSE = 23 ± .9)(Cheng et al, 2012; Golob and Starr, 2000). In contrast, P50 latency has been comparable between clinical groups and age-matched controls (Cheng et al, 2012; Golob and Starr, 2000; Golob et al, 2007; Irimajiri et al, 2005; Irimajiri et al, 2010) in all but one study that found longer latencies in MCI patients and a correlation between larger amplitude and longer latency P50 response to distractor tones (Golob et al, 2002). …”

Executive Dysfunction in MCI: Subtype or Early Symptom

“…The later component P3 has been shown to be associated with APOE in healthy controls. Irimajiri et al [81] found reduced amplitude among healthy female e4 carriers in auditory task, and Espeseth et al [82] found e4-related reduction of visual P3a amplitudes. Together, these findings indicate a potential clinical significance of individual differences in the attention-related ERP components N1, N2, and P3.…”