Table 1.

Model variables and parameters.

Entity	Description	Value*	Units
K synthesize	Rate that tau is synthesized in neuron	9.70 * 107	pg/hr/brain
K catabolize	Rate that tau is catabolized in neuron	9.70 * 107	pg/hr/brain
K release	Rate that tau is released from neuron	7.08 * 103	pg/hr/brain
K nft	Rate that soluble tau is converted to NFT	unknown	pg/hr/brain
K losses	Rate that tau is lost in drainage pathways	6.43 * 103	pg/hr/brain
K drain	Rate that tau is drained from CSF	7.08 * 103	pg/hr/brain
K absorb	Rate tau is absorbed into plasma	6.51 * 102	pg/hr/brain
K eliminate	Rate tau is eliminated from plasma	6.51 * 102	pg/hr/brain
k d	CSF first-order elimination rate constant	7.0 * 10−2	hr −1
k r	Brain first-order release rate constant	9.2 * 10−8	hr −1
k a	Plasma first-order absorption rate constant	7.0 * 10−2	hr −1
k e	Plasma first-order elimination rate constant	6.9 * 10−2	hr −1
k c	Brain first-order catabolism rate constant	1.26 * 10−3	hr −1
V csf	Volume of CSF compartment	300	ml
V brain ‡	Volume of brain compartment	1,300	g
V plasma	Volume of plasma compartment	3,500	ml
CSF half-life	Tau half-life in CSF compartment	9.9	h
Brain half-life†	Tau half-life in brain compartment	552	h
Plasma half-life	Tau half-life in plasma compartment	10	h
Plasma Tmax	Time to maximum tau plasma level after TBI	8	h

^*centered Values based on normal values from Table 2. Rates are calculated on a whole brain basis assuming a typical 1,300 g brain with combined 300 ml in CSF-ISF compartment and 3,500 ml in plasma compartment. The kinetic model allows re-calculation of C_brain, C_csf, and C_plasma in Alzheimer's disease based on alterations in either rates or rate constants (Figures 2A–6B).

^†Neuronal half-life based on human isotopic studies (Sato et al., 2018).

^‡By convention, brain size is quantified in g rather than ml.