Table 3. Group Differences in Seasonal Change in 5-HTT BP_ND in Participants Undergoing [¹¹C]DASB PET in Spring-Summer and Fall-Winter.

Brain region	Kruskal–Wallis H-test		Mann–Whitney U-test
			Moderate SAD vs Healthya		Severe SAD vs Healthyb
	χ(2)2c	p-Value	Ud	p-Value	Ud	p-Value
Prefrontal cortex	8.82	0.01	84.0	0.78	42.5	0.005
Anterior cingulate cortex	9.62	0.008	77.0	0.54	37.0	0.003
Dorsal putamen	10.09	0.006	100.0	0.64	40.0	0.004
Thalamus	10.45	0.005	106.0	0.45	41.0	0.004
Dorsal caudate	7.01	0.03	99.0	0.67	55.5	0.02
Ventral striatum	8.84	0.01	106.0	0.45	48.0	0.01
Midbrain	8.71	0.013	51.0	0.07	45.0	0.007
Hippocampus	5.26	0.07	91.0	0.96	62.0	0.048

5-HTT BP_ND, serotonin transporter binding potential (non-displaceable); Kruskal–Wallis H, non-parametric test; Mann–Whitney U, non-parametric equivalent of an independent samples t-test.

^an=9 (Moderate SAD) vs n=20 (Healthy).

^bn=11 (Severe SAD) vs n=20 (Healthy).

^cKruskal–Wallis test statistic.

^dMann–Whitney U-test statistic.