Table 2.

Simultaneous equation regression model of the direct and total effects of age and years of exposure to RHI on CD68 cell density and tau pathology (AT8 tau density)

	Standardized direct effects		Standardized total effects
	Effect/Std error/t value/p value		Effect/Std error/t value/p value
	CD68 Density	AT8 Tau Density	CD68 Density	AT8 Tau Density
Age	−0.0195	0.5125	0.006044	0.5136
	0.1003	0.0682	0.1009	0.0691
	−0.1948	7.5184	0.0599	7.4306
	0.8456	<.0001	0.9523	<.0001
RHI Exposure (Years)	0.3911	0.4614	0.4178	0.5349
	0.0852	0.071	0.0917	0.0681
	4.5911	6.4999	4.5551	7.8586
	<.0001	<.0001	<.0001	<.0001
CD68 Density		0.1759		0.1774
		0.0499		0.0507
		3.5271		3.5005
		<.0001		<.0001
AT8 Tau Density	0.0498		0.0503
	0.0112		0.0114
	4.4363		4.4058
	<.0001		<.0001

Simultaneous equation regression was used to analyze the direct and total effects. Bolded numbers represent significant p values. Visual pathway analysis can be found in Fig. 2