Table 1. Mathematical parameters describing the functional interactions among various cell types.

Rate	1/year	Pathway	S(Ns)	S(Nd)	S(M1)	S(M2)	Sensitivity
α1	10−5	Aq → Ns	50000	−50000	−6000	6000	Strong
α2	10−3	Ap → Nd	−500	500	−60	60	Weak
α3	10−2	M1 → Nd	−200	200	−35	35	Weak
α4	10−4	M2 → Aq	500	−500	150	−150	Weak
α5	10−2	M1 → Ap	−3	3	1	−1	Weak
α6	10−2	Ns → M2	500	−500	−6000	6000	Weak
α7	10−4	Aq → M2	5000	−5000	−50000	50000	Strong
α8	10−2	Aβ ⊥ M2	−400	400	5000	−5000	Moderate
α9	10−2	M1 ⊥ M2	−30	30	250	−250	Weak
α10	10−2	Nd → M1	−8	8	90	−90	Weak
α11	10−2	Ns ⊥ M1	500	−500	−6000	6000	Moderate
α12	10−4	Aq ⊥ M1	5000	−5000	−50000	50000	Strong
α13	10−2	Aβ → M1	−400	400	5000	−5000	Moderate
α14	10−4	M2 ⊥ M1	5000	−5000	−50000	50000	Strong
α15	1	Ns → Aβ	−10	10	100	−100	Weak
α16	10−2	M2 ⊥ Aβ	100	−100	−1000	1000	Weak
αr	1	M2 ⊥ Aβ	8	−8	−100	100	Weak

The rates α_i associated with the pathways of the AD mechanism, and the sensitivities of the N_s and N_d populations to variations in the values of α_i. The values for the sensitivity coefficients S(N_{j, j = s, d})  =  dN_j/dα_i are determined after 20 years for ±2.5% perturbations in each α_i value. A cell population is more sensitive to a change in a rate that produces a larger value of |S(N_j)|. Positive S(N_j) imply that a rate contributes to an increase in N_j while a negative value entails a corresponding population decrease.