Table 1.
Linear regression models parameters illustrating the relationship between GABA+ concentration and episodic memory performance.
| Variable | β(95% CI) | t-value | p-value |
|---|---|---|---|
| Baseline Model | |||
| Age [years] | 0.00 (−0.01;0.01) | 0.69 | 0.501 |
| Education, ISCED | −0.01 (−0.07;0.04) | −0.61 | 0.551 |
| GABA+ level, SD increase | 0.11 (0.04;0.18) | 3.21 | 0.007 |
| ApoE ɛ4, Positive | −0.02 (−0.13;0.10) | −0.32 | 0.757 |
| Sex, Male | 0.12 (0.02;0.22) | 2.72 | 0.019 |
| GABA+ × ApoE ɛ4 | 0.00 (−0.11;0.11) | 0.01 | 0.990 |
| GABA+ × Sex | −0.12 (−0.24;0.00) | −2.17 | 0.051 |
| Final model | |||
| GABA+, SD increase | 0.11 (0.05;0.17) | 3.92 | 0.001 |
| Sex, Male | 0.12 (0.04;0.21) | 3.10 | 0.007 |
| GABA+ × Sex | −0.11 (−0.20;−0.03) | −2.74 | 0.015 |
Linear regression models were constructed using the proportion of correctly recognized TBR words as the dependent variable, while adjusting for GABA+, age, sex, education, the presence of the ApoE ε4 allele, and for both the GABA+ level × ApoE ε4 and GABA+ level × sex interactions. The final model displayed was obtained after selecting variables via backward stepwise elimination. Female sex is the reference category; thus, the main effect of GABA+ level showed in the final model represents the association between GABA+ concentration and episodic memory performance in females. The adjusted R2 values were 0.34 and 0.48 for the baseline and final models, respectively. Listed are β coefficients and their 95% confidence intervals, t-statistics, and p-values.