Table 2.

Stepwise multiple regression model predicting right and left ventral striatum volumes.

Right Ventral Striatum
Step	Variable Addeda	β	t-statistic	p-value	R2 Change
1	Age	.11	.76	.44	.47
	Gender	.24	1.41	.17
	Total Brain Volume	.56	3.98	.0004
	Striatal D2/3 Receptor Occupancy	−.03	−.17	.87
2	Positive Symptomsc	.14	.75	.46	.004
	Depressed Symptomsc	−.12	.76	.45
3	Amotivation Factorc	−.38	-2.48	.01	.08
Left Ventral Striatum
Step	Variable Addedb	β	t-statistic	p-value	R2 Change
1	Age	.05	.36	.73	.53
	Gender	−.03	−.17	.87
	Total Brain Volume	.68	5.08	.00002
	Striatal D2/3 Receptor Occupancy	−.06	−.43	.67
2	Positive Symptomsc	.10	.60	.55	.003
	Depressed Symptomsc	.02	.12	.91
3	Amotivation Factorc	−.31	−2.17	.03	.06

Note: For ease of presentation, only the regression weights from the final model are shown.

^aOverall model: r² = .55, F_1,33 = 6.14, p = .01.

^bOverall model: r² = .60, F_1,33 = 4.42, p = .03.

^cCalculated using derived factor scores from the Positive and Negative Syndrome Scale.