Table 2. Results from Cross-Sectional Model.

Cross-sectional general linear model of the association of apathy to regional FDG metabolism and covariates displaying predictors retained in the final model

Model: R2=0.154, (df=5, 396) F=14.40, p<0.0001	β (Adjusted Mean)	95% CI for β	F	df	p	% Variance Total	% Variance Partial
Baseline diagnosis			14.89	(2, 396)	<0.0001	5.9	6.5
AD	0.47 (0.56)	(0.29, 0.64)
MCI	0.14 (0.23)	(0.01, 0.27)
CN	0.00 (0.09)
Posterior cingulate	−0.63	(−1.22, −0.044)	4.46	(1, 396)	0.035	0.74	0.85
Sex
Female	−0.13(0.23)	(−0.24, −0.016)	5.04	(1, 396)	0.025	0.86	1.00
Male	0.00 (0.36)
Antidepressant medication use
No	−0.14 (0.22)	(−0.28, −0.011)	4.55	(1, 396)	0.034	0.76	0.87
Yes	0.00 (0.37)

Cross-sectional general linear model of the association of apathy to regional FDG metabolism and covariates. AD (Alzheimer's disease), β (partial unstandardized regression coefficient estimate), CI (confidence interval), CN (cognitively normal elderly), MCI (mild cognitive impairment), F: F test statistic, df: degrees of freedom. 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 diagnosis, sex, and antidepressant use, β weights as well as Adjusted Means (group means adjusted for other predictors) are reported. For Post Hoc Pairwise Tests of Diagnostic Groups: AD vs CN: t=5.32, df=396, p<0.0001; MCI vs CN: t=2.11, df=396, p<0.035; AD vs MCI: t=4.44, df=396, p<0.0001.

“%Variance Total” represents percent of total variance of NPI-Q Apathy (Neuropsychiatric Inventory Questionnaire brief form, apathy item) uniquely associated with the indicated predictor (unbiased population estimate), “%Variance Partial” represents percent of variance of NPI-Q Apathy with portion associated with other predictors pre-removed, which is uniquely associated with the indicated predictor (unbiased population estimate).