Table 1.
Changes of α-syn, tau, Aβ, and iron in PDD.
| Subject | α-syn | tau | Aβ | Iron | Summary finding | References |
|---|---|---|---|---|---|---|
| A53T transgenic monkey | ↑ | High α-syn correlated with increased rate of cognitive decline | Niu et al. (2015) | |||
| PDD flies | ↑ | α-Syn increases in PD model with cognitive dysfunction | Fatima and Siddique (2019) | |||
| Combined Lewy–Alzheimer transgenic mice | ↑ | ↑ | ↑ | Aβ, tau, and α-syn can synergistically exacerbate the aggregation and deposition of each other, thereby promoting the additional acceleration of cognitive decline | Clinton et al. (2010) | |
| 5xFAD mice injected with α-syn | ↑ | ↑ | α-Syn PFFs injections into the brains of 5 × FAD mice accelerated cognitive decline in the Y-maze as early as 3 mpi, and cognitive performance progressively worsened with time | Bassil et al. (2020) | ||
| Prnp-SNCA*A53T mice (overexpressing mutated α-syn A53T mice) | ↑ | ↑ | Tau oligomers and α-syn are increased in the brains of Prnp-SNCA*A53T mice, indicating a cognitive function deficit, based on the inability to discriminate between novel and familiar objects | Gerson et al. (2018) | ||
| PDD C57BL/6 mice | ↑ | Increased Aβ is associated with decreased cognitive function | Ba et al. (2019) | |||
| PDD rat | ↑ | ↑ | Accumulation of α-syn and tau hyperphosphorylation are associated with decreased cognitive function. The injured insulin signaling pathway may be involved in this dopamine-dependent cognitive impairment | Yang et al. (2020) | ||
| PDD C57BL/6 mice | ↑ | ↑ | α-Syn and Aβ pathology are associated with the cognitive status of PDD | Choi et al. (2019) | ||
| overexpressing human α-syn rat | ↑ | The rats overexpressing human α-syn exhibited spatial learning and memory deficits in the Morris water maze task | Hall et al. (2013) | |||
| Mice expressing human wild-type α-syn under the Thy1 promoter | ↑ | Overexpressing human α-syn mice exhibit deficits in cholinergic systems involved in cognition, and cognitive deficits in domains affected in early PD | Magen et al. (2012) | |||
| PD patients | ↑ | Brain tissue iron, measured using quantitative susceptibility mapping, can track cognitive involvement in PD. This may be useful to detect signs of early cognitive change | Thomas et al. (2020) | |||
| PDD patients and PD patients | ↑ | Higher iron deposition is also observed in the unilateral hippocampus of the PDD patients when compared to non-demented PD patients. Moderate correlation of iron content in the PD and PDD patients with both cognitive and other neuropsychiatric impairment is found. | Li et al. (2018) |