Synucleinopathies: common features and hippocampal manifestations

Area of Science:

• Neuroscience
• Neuropathology
• Synucleinopathies

Background:

• Parkinson's disease (PD), dementia with Lewy Bodies (DLB), and multiple system atrophy (MSA) are synucleinopathies defined by alpha-synuclein inclusions.
• These disorders present overlapping symptoms but differ in affected brain regions and cell types, complicating differential diagnosis.
• Cognitive impairment and depression are common, linked to hippocampal dysfunction in these conditions.

Purpose of the Study:

• To investigate the role of alpha-synuclein aggregates in hippocampal dysfunction within synucleinopathies.
• To elucidate the mechanisms underlying cognitive and neuropsychiatric manifestations in PD, DLB, and MSA.

Main Methods:

• Review of existing evidence on alpha-synuclein pathology in the hippocampus.
• Analysis of the relationship between specific alpha-synuclein species and hippocampal function.
• Correlation of neuropathological findings with clinical symptoms of cognitive impairment and depression.

Main Results:

• While inclusions are present, smaller alpha-synuclein aggregates (oligomers) are increasingly implicated as pathogenic.
• These oligomers are hypothesized to disrupt neurotransmission and neurogenesis within the hippocampus.
• This disruption is proposed as a key mechanism for hippocampal dysfunction and associated neuropsychiatric symptoms.

Conclusions:

• Small alpha-synuclein aggregates, rather than solely large inclusions, are likely the primary drivers of hippocampal dysfunction in synucleinopathies.
• Understanding the role of these oligomers is crucial for explaining neuropsychiatric symptoms in PD, DLB, and MSA.
• Targeting alpha-synuclein oligomers may offer new therapeutic strategies for cognitive and mood disorders in these diseases.