. 2015 Apr 15;11:1067–1076. doi: 10.2147/NDT.S81011

Table 4.

Effects of khat chewing and paranoid schizophrenia on plasma levels of serotonin (5-HT) and its metabolite (HIAA), in comparison with healthy non-khat-chewer subjects

Variables	Healthy subjects (n=37)		Schizophrenic subjects (n=42)
	HNKc (n=20)	HKc (n=17)	SNKc (n=21)		SKc (n=21)
	HNKc (n=20)	HKc (n=17)	SNKch (10 mg/day) (n=10)	SNKcr (5 mg/day) (n=11)	SKch (10 mg/day) (n=10)	SKcr (5 mg/day) (n=11)
Serotonin (5-HT) (ng/mL)	199.40±2.78	262.18±2.05^***	221.3±1.89^▼▼▼	206.36±3.16	309.5±5.03^***,^⋄⋄⋄	297.6±2.27^***,^⋄⋄⋄
5-HIAA (nmol/L)	58.10±1.18	85.41±1.62^***	64.3±4.19	59.09±1.42	99.6±1.8^***,^⋄⋄⋄	93.82±0.93^***,^⋄

Notes: Each value represents as mean ± SEM.

For comparison between khat-chewers and non-chewers between groups and within groups,

^▼

for comparison between SNKch or SNKcr and HNKc, and ⋄for comparison between SKch or SKcr and HKc. Note that mostly rest of all other comparisons were significant.

^⋄

P<0.05;

^{***,▼▼▼,⋄⋄⋄}

P<0.001.

Abbreviations: 5-HT, 5-hydroxytryptamine; HIAA, hydroxyindoleacetic acid; S, schizophrenic; K, khat; c, chewing; N, non; r, risperidone; h, haloperidol; SEM, standard error of the mean.