Table 1 Evidences of impaired neuroregeneration in AD and PD
Neurorestorative field | Â | Evidence of impairment | Evidence of compensatory mechanism |
|---|---|---|---|
Neurogenesis | AD | Decreased number of NPCs and altered division rates [21] | Increased neuroproliferation markers [16] |
| Â | PD | Reduced number of NPCs [28] | Increased number of PSA-NCAM + cells [29] |
Neuroprotection | AD | Low BDNF mRNA and protein levels [37] | Upregulation of glial truncated TrkB [40] |
| Â | Â | Possibly upregulation of NGF with ageing and dementia [61, 62, 87] | |
|  |  |  | Aβ stimulates NGF astrocytic secrection [51] |
| Â | Â | Â | High GDNF levels in cerebrospinal fluid |
| Â | PD | Low BDNF mRNA and protein levels [37] | BDNF pretreatment protects dopaminergic neurons [34] |
| Â | Â | Low GDNF protein levels [66] | Â |
Neuroplasticity | AD | Synaptic loss [77] | "Dynamic synaptic reorganization" [82]. |
| Â | Â | LTP impairment by Abeta oligomers and inflammatory environment [85] | NCAM increase in dentate gyrus [83] |
| Â | PD | Loss of dendritic spines following loss of dopaminergic input [90] | Â |
|  |  | Impaired synaptic plasticity in several models of PD [87–89] |  |