Table 1.

Similarities and Differences between PD and Manganese Toxicity.

	Parkinson’s Disease	Manganese Toxicity	Reference
Genetic Determination	Yes, can be autosomal dominant or autosomal recessive. Approximately 10–20% of cases linked to genetic causes	No	[199]
Selective DA sensitivity	Yes	Yes- however several studies have pointed to the selectivity of glutamate and possibly GABA	[57–59]
Brain regions affected	Substancia nigra pars compacta (SNpc) primarily and striatum	Globus pallidus primarily but striatum, and substancia nigra may also be involved	[6, 19, 199]
Mitochondrial dysfunction/ oxidative stress	Yes	Yes	[85, 199]
L-DOPA responsive	Yes	Generally unresponsive to L-DOPA however, some motor symptoms reversed but with major side effects	[52]
Symptoms	Emotional and cognitive decline, bradykinesia, rigidity, tremors and postural instability.	Extrapyramidal syndrome	[19, 49, 200, 201]
		Slowed hand movements, irritability, aggressiveness and hallucinations.
	Later stages: masked-face, forward-flexed posture, gait freezing, shuffling steps, GI issues	Later stages: Rigidity, tremor, gait disturbances (slow and clumsy movements), hypokinesia, facial muscle spasms, propensity to fall backward when pushed, less frequent resting tremor, more frequent dystonia, a “cock-walk” collectively referred to as ‘manganism’