Table 4.

Neurotoxicity-associated predominant pathways affected by heavy metals and metalloids.

Heavy metals and metalloids	Principal pathways involved in neurotoxicity
	Caspase pathways	Others
Arsenic	•Caspase-9 by cyt c release [199]	•ROS generation [202] •Ca2+ imbalance [202] •p38 and JNK [202] •WNT and Notch [205] •Reduced acetylcholinesterase activity [201]
Cadmium	•Caspase-9 by p53 deficiency & reduced BCL-2 [97] •Caspase-8 by Fas-FasL [225]	•ROS generation [97] •Ca2+ accumulation [97] •mTOR & PI3K/AKT [224] •PTEN & AMPK [224]
Chromium	•Caspase-1 by NF-κB [226]
Iron		•Ferroptosis [229] •AP-1 [60] •PI3K/AKT [210]
Mercury	•Caspase-3 by PI3K/AKT [163]	•HIF-1α [212]
Nickel	•Caspase-9 by BAX, BID, and cyt c [227] •Caspase-8 and caspase-10 by Fas-FasL [75]
Vanadium	•Caspase-9 by cyt c release [124] •Caspase-8 by Fas-FasL [124]