PD Guide
Compensatory & Neuronal Health Mechanisms
In PD research, the biological processes that compensate for the loss of dopaminergic neurons in the course of disease progression such that the onset of motor symptoms is only observable after a large percentage of dopaminergic cells is lost are referred to in the literature as compensatory mechanisms. Similar processes may be presumed to operate to delay the surfacing of non-motor symptoms that result from neurodegeneration in PD, but there is little evidence of this at present (Bezard et al., 2009).
Compensatory mechanisms may or may not include well known examples of cellular processes known to enhance neuronal health and development such as neurotrophic factors; there are several attempts to enlist these factors as means of countering or repairing neurodegeneration.
Neurotrophic factors are secreted growth factors that can signal growth and differentiation, and block programmed cell death pathways. There is also clear evidence that new neurons can be generated in at least some regions of the adult brain, suggesting that this process could be used to repair damage to the brain. It is unclear whether disruption of these protective and/or restorative mechanisms is a direct cause of or reaction to PD, but research has focused on attempts to use the mechanisms for therapeutic purposes.