Table 2

Summary of linear and negative binomial mixed model results examining effect of TBI subtype on cognitive/behavioural scores

	Working memory (n=7350)		Verbal reasoning (n=7350)		Processing speed (n=6767)		Attention (n=6765)		Mild behavioural impairment (n=7139)
	B (95% CI)	P value	B (95% CI)	P value	B (95% CI)	P value	B (95% CI)	P value	Estimate (95% CI)	P value
Baseline
No concussion	0	–	0	–	0	–	0	–	0	–
nSRC	0.026 (−0.006 to 0.058)	0.117	0.025 (−0.021 to 0.071)	0.294	0.008 (−0.027 to 0.042)	0.663	−0.053 (−0.104 to −0.002)	0.041*	−0.299 (−0.386 to −0.212)	<0.001**
SRC	0.113 (0.038 to 0.188)	0.003**	0.199 (0.092 to 0.306)	<0.001**	0.051 (−0.028 to 0.131)	0.204	0.031 (−0.086 to 0.149)	0.599	−0.182 (−0.383 to 0.02)	0.077
Mixed concussion (nSRC+SRC)	−0.019 (−0.083 to 0.046)	0.570	0.025 (−0.067 to 0.117)	0.595	−0.017 (−0.086 to 0.052)	0.631	0.065 (−0.036 to 0.167)	0.208	−0.316 (−0.487 to −0.144)	<0.001**
Trajectories over increasing age (5-year increments)
Age†	0 (−0.012 to 0.011)	0.973	0.391 (0.371 to 0.411)	<0.001**	−0.124 (−0.138 to −0.11)	<0.001**	0.026 (0.006 to 0.046)	0.012*	0.1 (0.068 to 0.133)	<0.001**
Age²	−0.025 (−0.029 to −0.021)	<0.001**	−0.049 (−0.056 to −0.043)	<0.001**	−0.01 (−0.016 to −0.005)	<0.001**	−0.025 (−0.034 to −0.017)	<0.001**	−0.061 (−0.074 to −0.049)	<0.001**
nSRC^*Age	−0.009 (−0.027 to 0.01)	0.353	−0.012 (−0.045 to 0.021)	0.473	0.007 (−0.016 to 0.03)	0.579	0 (−0.034 to 0.033)	0.986	0.017 (−0.034 to 0.069)	0.510
SRC^*Age	0 (−0.041 to 0.042)	0.983	−0.042 (−0.118 to 0.035)	0.284	0.028 (−0.023 to 0.08)	0.285	−0.038 (−0.113 to 0.037)	0.320	−0.024 (−0.141 to 0.092)	0.682
Mixed concussion (nSRC+SRC)^*Age	0.035 (0 to 0.069)	0.052	−0.026 (−0.09 to 0.038)	0.421	−0.013 (−0.057 to 0.03)	0.544	−0.025 (−0.088 to 0.038)	0.433	−0.089 (−0.183 to 0.004)	0.062

The model was adjusted for sex, age, age², education, household income, smoking status, history of psychosis, history of mood disorder, history of anxiety disorder, history of hypertension, stroke, coronary heart disease, diabetes, hypercholesterolaemia and physical activity. This model compares all head injury groups to individuals in the cohort who have had no concussion, that is, a B of −0.211 at baseline means that the group had a mean score −0.211 SD lower than those with no head injuries.
*p<0.05.
**p<0.01.
†The unit of age is 5-year increments, that is, B indicates the number of SD change in cognitive score with each additional 5 years of age.
nSRC, non-sports-related concussion (ie, non-sports related); SRC, sports-related concussion.