Amitriptyline appears it "may" be the best possible choice, for some. I agree variable reactions to the drug, and some of its specific side effects, might prove it is not a good choice for others, and you should discuss the risks carefully with your doctor.
However, the ability of Amitriptyline to function as both an antidepressant and a sleep aid becomes very useful when the disease has progressed to the stage that makes uninterrupted sleep difficult. Then, given it is useful in addressing mutiple problems, the fact it is an "old" drug is, for some, among its most useful features, given that means it is available from WalMart as a prescription that costs only $4 to fill.
The unique fact that, alone among the antidepressants, the molecule also functions as a direct mimic of Nerve Growth Factor, also suggests it may provide a direct benefit in combatting the course of progression of the disease, through a neuroprotective effect that may help limit neuron cell death.
See, for instance, the Wikipedia entry for the drug:
"Recently, amitriptyline has been demonstrated to act as an agonist of the TrkA and TrkB receptors. It promotes the heterodimerization of these proteins in the absence of NGF and has potent neurotrophic activity both in-vivo and in-vitro in mouse models."
19. ^ Jang; Liu, X.; Chan, C.; Weinshenker, D.; Hall, R.; Xiao, G.; Ye, K. (2009).
Chemistry & biology 16 (6): 644–656. :.