Table 2.

Quality assessment of included studies based on the newcastle-ottawa scale for case–control studies. The articles were rated based on selection and characterization of cases and controls (Selection, max score 4), comparability between case and controls (Comparability, max score 2), and ascertainment of effects of microbiota (Exposure, max score 4), for a potential score ranging from 0 to 10 points.

Study	Year	Selection	Comparability	Exposure	Total
ASD
Finegold et al.45	2010	4	1	2	7
Gondalia et al.46	2012	4	1	2	7
De Angelis et al.57	2013	4	2	2	8
Kang et al.58	2013	4	1	2	7
Son et al.59	2015	4	1	2	7
Strati et al.60	2017	4	1	2	7
Kang et al.61	2017	4	1	2	7
Pulikkan et al.62	2018	4	1	2	7
Kang et al.63	2018	4	1	2	7
Berding et al.64	2018	3	1	2	6
Rose et al.47	2018	4	2	2	8
Zhang et al.48	2018	4	1	2	7
Coretti et al.49	2018	3	1	2	6
Li et al.50	2019	4	1	2	7
Carissimi et al.51	2019	4	0	2	6
Liu et al.52	2019	4	2	2	8
Zhai et al.53	2019	4	1	2	7
Ma et al.54	2019	4	2	2	8
Wang et al.55	2019	4	1	2	7
Plaza-Díaz et al.56	2019	3	2	2	7
ADHD
Aarts et al.65	2017	4	0	2	6
Prehn-Kristensen et al.66	2018	4	1	2	7
Jiang et al.	2018	4	1	2	7
Wang et al.	2019	4	1	2	7