Table 3. Longitudinal Mixed Effects Model of Association of Apathy and Regional FDG metabolism over time, displaying predictors retained in the final model.
Model: r =0.37, R2 =0.14, p<0.0001 for actual vs. predicted values (fixed); r=0.77, R2= 0.59, p<0.0001 for actual vs. predicted values (fixed and random)
| Predictor | Partial β | 95% CI for β | F | df | p |
|---|---|---|---|---|---|
| Diagnosis | 25.1 | (2, 396) | <0.0001 | ||
| AD | 0.49 | (0.35, 0.62) | |||
| MCI | 0.15 | (0.05, 0.26) | |||
| CN | 0.0 | ||||
| Posterior Cingulate | −0.66 | (−1.18, −0.14) | 6.22 | (1, 1047) | 0.013 |
| Supramarginal gyrus × time | −0.6 | (−1, −0.13) | 6.45 | (1, 1047) | 0.01 |
| Supramarginal gyrus | −0.14 | (−1, 0.71) | 0.11 | (1, 1047) | 0.74 |
| Time | 0.68 | (0.21, 1.16) | 8.18 | (1, 388) | 0.004 |
| Sex | |||||
| Female | −0.10 | (−0.19, −0.0090) | 4.68 | (1, 396) | 0.03 |
| Male | 0.00 | ||||
| Antidepressant medication use | |||||
| No | −0.12 | (−0.23, −0.02) | 5.55 | (1, 396) | 0.02 |
| Yes | 0.00 |
CI: confidence interval, df: degrees of freedom, F: F test statistic, AD (Alzheimer's disease), β (partial unstandardized regression coefficient estimate), CN (cognitively normal elderly), MCI (mild cognitive impairment). CN was used as a reference group in predictors coding diagnosis. For antidepressant medication use “yes” was the reference group of subjects taking antidepressant medications. For sex, male sex was the reference group. For Post Hoc Pairwise Tests of Diagnostic Groups: AD vs CN: t=6.96, df=396, p<0.0001; MCI vs CN: t=2.96, df=396, p<0.003; AD vs MCI: t=5.69, df=396, p<0.0001.