Cellular and extracellular white matter alterations indicate conversion to psychosis among individuals at clinical high-risk for psychosis

Figures & data

Table 1. Demographic and clinical characteristics of the sample.

Variable	HC		CHR		U/χ^2	p	CHR-NP		CHR-P		χ^2/U/T	p
	(n = 24)		(n = 24)				(n = 16)		(n = 8)
Sex (F/M)	11/13		12/12		χ^2 = 0.083	0.773	9/7		3/5		χ^2 = 0.835^a	0.659^a
	Mean	SD	Mean	SD			Mean	SD	Mean	SD
Age (years)	23.04	4.32	21.29	3.50	U = 354	0.174	21.50	3.65	20.88	3.36	χ^2 = 2.111^a	0.348^a
Education	(n = 23)		(n = 23)				(n = 16)		(n = 7)
(years)	14.63	2.83	13.11	3.00	U = 351.5	0.056	13.28	2.95	12.71	3.30	χ^2 = 4.031^a	0.133^a
Antipsychotic Medication			(n = 8)				5/16		3/8		χ^2 = 0.094	0.760
CPZE (mg/day)			168.75	148.92			180.00	172.16	150.00	132.29	U = 7	0.879
Duration (months)			3.61	5.58			4.29	6.77	2.23	2.42	U = 8	0.897
PANSS			(n = 23)				(n = 16)		(n = 7)
Positive			11.61	3.17			11.50	3.39	11.86	2.85	U = 61.5	0.737
Negative			9.65	2.71			9.56	3.03	9.86	1.95	U = 68.5	0.409
Global			26.52	5.63			26.63	6.30	26.29	4.11	T = −0.153	0.880
SOPS
Positive			(n = 22)				(n = 15)		(n = 7)
			5.86	4.78			4.73	4.54	8.29	4.68	U = 81	0.047*
Negative			(n = 20)				(n = 14)		(n = 6)
			5.65	4.68			5.43	4.88	6.17	4.58	U = 48
Disorganisation			(n = 21)				(n = 15)		(n = 6)			0.648
			2.19	2.16			1.93	2.12	2.83	2.32	U = 57	0.361

Note: F: female; M: male; CPZE: chlorpromazine equivalents; PANSS: Positive and Negative Syndrome Scale; SOPS: Scale of Prodromal Symptoms; HC: healthy controls; CHR: individuals at clinical high-risk for psychosis; CHR-NP: CHR individuals who did not develop psychosis; CHR-P: CHR individuals who developed psychosis; SD: standard deviation

^aThese test statistics reflect the comparison of three groups (HCs, CHR-P, CHR-NP); *significant at p < 0.05

Figure 1. White matter alterations in CHR-P compared to CHR-NP (p_FWE < 0.05). Global FA reductions in CHR-P comparing to CHR-NP appear to be explained both by FA_T reductions and FW increases in CHR-P as there is a considerable overlap between significant clusters (left panels). Diffusion measures averaged across corresponding significant clusters are presented as boxplots on the right.

Note: CHR: clinical high-risk for psychosis, CHR-P: CHR individuals who developed psychosis, CHR-NP: CHR individuals who did not develop psychosis, FA: fractional anisotropy, FA_T: fractional anisotropy of the tissue, FW: free-water

Figure 2. Correlations between positive symptoms and diffusion measures in CHR individuals (n = 28, p_FWE < 0.05). FA and FA_T (red) are inversely correlated, while FW (blue) is positively correlated with positive symptoms (left panels). Pearson’s correlations using diffusion measures averaged across corresponding significant clusters are shown on the right. Data points for CHR-P subjects are orange-coloured.

Note: CHR: clinical high-risk for psychosis, FA: fractional anisotropy, FA_T: fractional anisotropy of the tissue, FW: free-water, PANSS: Positive and Negative Syndrome Scale