Table 1.

Associations between the minor G allele in rs10158645, CSF concentration of KYNA, HVA and a history of psychosis in euthymic BD patients

Data set	rs10158645 MAF	CSF KYNA (nM)				CSF HVA (nM)				Psychosis
		N	r	P	IEa	N	r	P	IEb	N	OR (95% CI)	P
II	0.15	76	0.58	3 × 10−8	65 (36–101)c	72	0.54	7 × 10−7	0.71 (0.15–1.8)c	76	4.0 (1.4–12)	0.011
III	0.15	30	0.48d	7 × 10−3
IV	0.18									565	1.5 (1.1–2.0) 6.5 (1.5–28)e	0.020 0.013e
II+IV	0.17									641	1.6 (1.2–2.2) 7.3 (1.7–32)e	2 × 10−3 8 × 10−3

Abbreviations: BD, bipolar disorder; CI, confidence interval; CSF, cerebrospinal fluid; HVA, homovanillic acid; IE, indirect effect; KYNA, kynurenic acid; MAF, minor allele frequency; OR, odds ratio. All reported P-values are two sided.

^aIE = indirect effect for mediation. Non-parametric bootstrap method, the PROCESS script for SPSS (see http://afhayes.com/spss-sas-and-mplus-macros-and-code.html). Causal variable = allele frequency in rs10158645, mediator = CSF KYNA concentration and outcome variable = CSF HVA concentration. Direct effect = 43 (−0.53 to 86).

^bCausal variable = CSF KYNA concentration, mediator = CSF HVA concentration and outcome variable = psychosis (0/1). Direct effect = 0.15 (−0.61to 0.90).

^c95% Bootstrap CI (percentile bootstrap = 20 000).

^dSpearman’s coefficient.

^eIn sample I, only one patient was homozygous for the minor G allele in rs1018645 and the analysis was performed under an additive model. In sample II, 21 patients were homozygous for the minor G allele (18 with psychosis) and additional analyses under a recessive model was performed in sample II and the combined sample (I+II).