Figure 3.

Model-derived least squares means of phosphocholine (PCho) area under the curve adjusted for age and sex (error bars represent 95% confidence intervals adjusted for multiple comparisons) extracted from theoretical voxels composed of 100% gray matter and 100% white matter. Analysis of the PCho total tissue reduction in patients with primary insomnia revealed a significant difference in association with primary insomnia between gray matter and white matter (t₄₅₇ = -2.58; P = 0.04). Post hoc testing indicates that the observed reduction in PCho is occurring primarily in white matter (t₄₃₇ = 5.66; P < 0.0001) as opposed to gray matter (t₄₀₃ = -0.59; not significant). The dashed blue line is the total tissue main effect of the model (Table 1), which is depicted for comparison purposes.