The Noradrenergic System is a Major Component in Parkinson’s Disease

Abstract

1.1 Dopaminergic neuronal loss in Parkinson’s disease Parkinson’s disease (PD) is a neurological disorder that affects approximately 2% of the elderly population, and as our population continues to age, the incidence will only increase (Singh et al., 2007). PD is commonly characterized by various motor deficits including tremor, rigidity and bradykinesia (Singh et al., 2007). The cause of these motor symptoms is the loss of dopaminergic neurons in the substantia nigra pars compacta (SN) and reduced dopamine (DA) levels in the striatum (Damier et al., 1999; Gibb, 1991; Gibb and Lee, 1991). However, the appearance of PD symptoms does not occur until 70-80% of the dopaminergic neurons are lost. In the progression of this disorder, the loss of dopaminergic neurons is not observed until Stage 3 (out of 6 Stages) of the disorder (Braak et al., 2003a, 2003b, 2006).