Dear NBS experts, 

Hello all, I am performing NBS for group comparison between high group and low group with 3 covariates (age, sex, neuropsychological test). 
The results turn out great, but it seems quite sparse in a way, because it shows multiple significant networks, total of 10! 
With t-threshold of 4.0, it gives 4 networks (I attached the screenshot of the result page (UPDRS_FA_40_LtDom_network#.jpg))
With t-threshold of 4.5, it gives 10 networks (attached the results(UPDRS_FA_45_LtDom_network#.jpg)). 
Few networks show consistent clusters, but some show a one edge as a network. 
I know it is possible outcome, but still wonder how to manage and to interpret this result.
How can this be possible? In what algorithmic logic? 

Thank you in advance. 

I will wait for your the reply!