TABLE S1.

Proportion of Children in the Avon Longitudinal Study of Parents and Children (ALSPAC) Cohort Whose Parents Endorsed the Presence of “Tics or Twitches” in Their Son/Daughter at Each Age-Specific Questionnaire

Child's Age at Time of Completion of Maternal Questionnaire	Children with Data Available at Age 13 Years	Children with Data Not Available at Age 13 Years	Overall Sample
1 Year 6 months	0.42% (26/6,155)	0.96% (41/4,280)	0.64% (67/10,435)
2 Years 6 months	0.54% (32/5,973)	0.73% (27/3,678)	0.61% (59/9,651)
3 Years 6 months	1.39% (84/6,048)	1.78% (62/3,476)	1.53% (146/9,524)
4 Years 9 months	0.80% (47/5,909)	1.25% (37/2,961)	0.95% (84/8,870)
5 Years 9 months	1.18% (68/5,740)	1.72% (41/2,379)	1.34% (109/8,119)
6 Years 5 months	1.37% (79/5,751)	2.22% (49/2,210)	1.61% (128/7,961)
7 Years 7 months	1.64% (93/5,681)	2.65% (51/1,922)	1.89% (144/7,603)
10 Years 8 months	2.29% (135/5,903)	3.32% (43/1,296)	2.47% (178/7,199)
13 Years	17.9% (1211/6,768)	NA	17.9% (1211/6,768)

Note: Rates of positive response to the single question about tics at each age are separated into children who had data available at age 13 years (eligible for inclusion in the current study) and children who were lost to follow-up before age 13 years (not eligible for inclusion in the current study due to absence of detailed tic questionnaire data only available at age 13). Rates of positive responses in the overall sample are also provided. These data do not include subjects with intellectual disability, autism, or IQ <80 as described in the main text.