Table 3.

Predicted regional NAA concentration in association with PTSD, alcohol abuse (A), a PTSD*A interaction and other confounding factors

Dependent variable	Independent variables	Regression coefficients		Standard error		P-value
		Left	Right	Left	Right	Left	Right
NAA, hippocampus	Creatine	14.1	13.4	1.0	0.9	<0.001	<0.001
	Age	-0.1	-0.3	0.1	0.1	0.1	<0.001
	A	0.8	0.2	0.7	0.6	0.3	0.7
	PTSD	-2.1	-1.8	0.9	0.7	0.02	0.02
	PTSD*A	-0.5	0.3	0.8	1.1	0.5	0.8
NAA, anterior cingulated	Creatine	10.4	12.7	2.3	1.7	<0.001	<0.001
	Age	0.0	0.0	0.1	0.1	0.7	0.6
	A	0.2	0.1	0.3	0.1	0.4	0.8
	PTSD	-0.5	-0.7	0.2	0.3	0.03	0.04
	PTSD*A	-0.2	-0.2	0.2	0.3	0.4	0.4

Note: Hippocampal NAA includes adjustment for creatine variations while NAA in the anterior cingulate is independent of creatine variations. Variables are listed in the order they were entered into the models. MRSI results included 85 subjects, who had MRSI data of acceptable quality.