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Interaction between years of education and APOE ε4 status on frontal and temporal metabolism.

Arenaza-Urquijo EM, Gonneaud J, Fouquet M, Perrotin A, Mézenge F, Landeau B, Egret S, De la Sayette V, Desgranges B, Chételat G - Neurology (2015)

Bottom Line: We tested the interaction effect between years of education and APOE ε4 status (carrier vs noncarrier) on FDG-PET and structural MRI within the whole brain (voxel-wise) adjusting for age and sex.Computed florbetapir standardized uptake value ratios were used for complementary analyses.Higher metabolism in higher (compared to lower) educated APOE ε4 carriers was found in regions that sustain episodic memory.

View Article: PubMed Central - PubMed

Affiliation: From INSERM U1077 (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., S.E., V.D.l.S., B.D., G.C.); Université de Caen Basse-Normandie (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., V.D.l.S., B.D., G.C.) and Ecole Pratique des Hautes Etudes (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., V.D.l.S., B.D., G.C.), UMR-S1077; CHU de Caen, U1077 (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., S.E., B.D., G.C.); and CHU de Caen (S.E., V.D.l.S.), Service de Neurologie, Caen, France.

No MeSH data available.


Related in: MedlinePlus

Box graphs for the pairwise comparison between higher and lower educated carriers and noncarriersFrom left to right: noncarriers (in blue), lower educated APOE ε4 carriers (in light red), and higher educated APOE ε4 carriers (in red). ns = nonsignificant. *p < 0.05.
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Figure 2: Box graphs for the pairwise comparison between higher and lower educated carriers and noncarriersFrom left to right: noncarriers (in blue), lower educated APOE ε4 carriers (in light red), and higher educated APOE ε4 carriers (in red). ns = nonsignificant. *p < 0.05.

Mentions: We aimed to understand increased frontal and temporal metabolism as a function of years of education in APOE ε4 carriers. More specifically, we aimed at assessing whether higher educated APOE ε4 carriers showed (1) equivalent/preserved frontal and temporal metabolism as compared to noncarriers, which could reflect metabolism maintenance, as predicted by the brain maintenance theory; or (2) increased frontal and temporal metabolism as compared to noncarriers, which may reflect compensatory mechanisms, in line with brain and cognitive reserve theories. Thus, we first compared the extracted FDG-PET values from the areas showing a significant APOE ε4 × years of education interaction between noncarriers (the reference group) and the APOE ε4 carriers divided into 2 groups of higher (n = 12) and lower (n = 16) educated participants, based on the 50th percentile (years of education >12 or ≤12). The 2 groups did not differ in age (p = 0.22) or sex (p = 0.07). Then, the same analyses were carried out within each significant cluster (i.e., bilateral hippocampus/parahippocampus, left middle temporal, and right prefrontal) because different education-related effects and mechanisms (e.g., preservation or compensation) may have distinct topographic expression.13 We used the Dunnett procedure, which allows testing a specific set of pairwise comparisons of interest, being thus less conservative than other multiple comparison tests (i.e., we do not correct for the comparisons that we are not interested in) but still more conservative than pairwise t test. When all the areas were considered together, higher educated APOE ε4 carriers showed increased metabolism as compared to noncarriers (t = 0.06; p = 0.03), while no difference was found between lower educated APOE ε4 carriers and noncarriers. However, when the analyses were performed within each significant cluster, lower educated APOE ε4 carriers showed decreased metabolism as compared to the noncarriers in the right and left parahippocampus/hippocampus areas, and a trend was found in the same direction for the right prefrontal lobe (table 2). In contrast, higher educated APOE ε4 carriers showed comparable metabolism to noncarriers in the parahippocampus/hippocampus and right prefrontal lobe and increased metabolism in the left middle temporal lobe (figure 2).


Interaction between years of education and APOE ε4 status on frontal and temporal metabolism.

Arenaza-Urquijo EM, Gonneaud J, Fouquet M, Perrotin A, Mézenge F, Landeau B, Egret S, De la Sayette V, Desgranges B, Chételat G - Neurology (2015)

Box graphs for the pairwise comparison between higher and lower educated carriers and noncarriersFrom left to right: noncarriers (in blue), lower educated APOE ε4 carriers (in light red), and higher educated APOE ε4 carriers (in red). ns = nonsignificant. *p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4626241&req=5

Figure 2: Box graphs for the pairwise comparison between higher and lower educated carriers and noncarriersFrom left to right: noncarriers (in blue), lower educated APOE ε4 carriers (in light red), and higher educated APOE ε4 carriers (in red). ns = nonsignificant. *p < 0.05.
Mentions: We aimed to understand increased frontal and temporal metabolism as a function of years of education in APOE ε4 carriers. More specifically, we aimed at assessing whether higher educated APOE ε4 carriers showed (1) equivalent/preserved frontal and temporal metabolism as compared to noncarriers, which could reflect metabolism maintenance, as predicted by the brain maintenance theory; or (2) increased frontal and temporal metabolism as compared to noncarriers, which may reflect compensatory mechanisms, in line with brain and cognitive reserve theories. Thus, we first compared the extracted FDG-PET values from the areas showing a significant APOE ε4 × years of education interaction between noncarriers (the reference group) and the APOE ε4 carriers divided into 2 groups of higher (n = 12) and lower (n = 16) educated participants, based on the 50th percentile (years of education >12 or ≤12). The 2 groups did not differ in age (p = 0.22) or sex (p = 0.07). Then, the same analyses were carried out within each significant cluster (i.e., bilateral hippocampus/parahippocampus, left middle temporal, and right prefrontal) because different education-related effects and mechanisms (e.g., preservation or compensation) may have distinct topographic expression.13 We used the Dunnett procedure, which allows testing a specific set of pairwise comparisons of interest, being thus less conservative than other multiple comparison tests (i.e., we do not correct for the comparisons that we are not interested in) but still more conservative than pairwise t test. When all the areas were considered together, higher educated APOE ε4 carriers showed increased metabolism as compared to noncarriers (t = 0.06; p = 0.03), while no difference was found between lower educated APOE ε4 carriers and noncarriers. However, when the analyses were performed within each significant cluster, lower educated APOE ε4 carriers showed decreased metabolism as compared to the noncarriers in the right and left parahippocampus/hippocampus areas, and a trend was found in the same direction for the right prefrontal lobe (table 2). In contrast, higher educated APOE ε4 carriers showed comparable metabolism to noncarriers in the parahippocampus/hippocampus and right prefrontal lobe and increased metabolism in the left middle temporal lobe (figure 2).

Bottom Line: We tested the interaction effect between years of education and APOE ε4 status (carrier vs noncarrier) on FDG-PET and structural MRI within the whole brain (voxel-wise) adjusting for age and sex.Computed florbetapir standardized uptake value ratios were used for complementary analyses.Higher metabolism in higher (compared to lower) educated APOE ε4 carriers was found in regions that sustain episodic memory.

View Article: PubMed Central - PubMed

Affiliation: From INSERM U1077 (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., S.E., V.D.l.S., B.D., G.C.); Université de Caen Basse-Normandie (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., V.D.l.S., B.D., G.C.) and Ecole Pratique des Hautes Etudes (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., V.D.l.S., B.D., G.C.), UMR-S1077; CHU de Caen, U1077 (E.M.A.-U., J.G., M.F., A.P., F.M., B.L., S.E., B.D., G.C.); and CHU de Caen (S.E., V.D.l.S.), Service de Neurologie, Caen, France.

No MeSH data available.


Related in: MedlinePlus