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. Author manuscript; available in PMC: 2014 May 1.
Published in final edited form as: Neuropsychologia. 2013 Mar 13;51(6):1124–1131. doi: 10.1016/j.neuropsychologia.2013.02.022

Table 3.

Interaction effects of age 20 Armed Forces Qualification Test (AFQT20) and hippocampal volume on CVLT total words in trials 1 – 5. Statistics presented separately for total, left, and right hippocampal volume.

Covariates Model 1 Model 2
age, eTIV age, eTIV, APOE
df F p df F p
Total hippocampal volume
 Interaction with continuous AFQT20 204 7.47 0.007 191 7.41 0.007
 Interaction with categorical AFQT20 59 4.63 0.035 54 4.72 0.034
Left hippocampal volume
 Interaction with continuous AFQT20 204 8.05 0.005 191 8.70 0.004
 Interaction with categorical AFQT20 59 4.52 0.038 52 5.51 0.023
Right hippocampal volume
 Interaction with continuous AFQT20 204 5.95 0.016 191 5.40 0.021
 Interaction with categorical AFQT20 59 4.28 0.043 52 3.64 0.062

Note. Model 1 covariates include age and estimated total intracranial volume (eTIV). Model 2 includes also APOE ε4 status (carrier vs. non-carrier) as an additional covariate. Twin relatedness controlled in all analyses. Type three effects controlled also for the main effects of AFQT and hippocampal volume.