092 Brain amylin accumulation in Parkinson’s disease is not driven by type 2 diabetes mellitus

Introduction

Type 2 diabetes (T2D) is increasingly recognised as being a risk factor for Parkinson’s disease (PD). One proposed mechanism is an interaction between amylin, a highly amyloidogenic pancre- atic hormone, and α-synuclein. Amylin accelerates α-synuclein aggregation in vitro and interacts with α-synuclein in the locus coeruleus, and neuronal, extracellular and vessel-associated amylin deposits have been reported in Alzheimer’s disease and control brains. However, the molecular link between amylin and PD and the role of T2D remains unclear.

Methods

The burden of amylin accumulation in post mortem anterior cingulate and frontal gyrus tissue from PD and non-neurodegenerative control cases, with and without T2D, was investigated using immu- nohistochemistry and western immunoblotting.

Results

Immunohistochemistry revealed very infrequent amylin labelling of senile plaques and neurofibril- lary tangles along with rare perivascular amylin deposits in PD and control brains, irrespective of T2D status. Although western immunoblotting revealed significantly increased amylin levels in PD cases compared to controls, there was no difference between diabetic and non-diabetic cases.

Conclusion

Our results do not support the hypothesis that brain amylin accumulation is increased by T2D. Higher amylin levels in PD may result from blood-brain barrier dysfunction but further studies are needed to clarify the relevance to PD pathogenesis.

Faster disease progression in Parkinson's disease with type 2 diabetes is not associated with increased α-synuclein, tau, amyloid-β or vascular pathology

AIMS

Growing evidence suggests a shared pathogenesis between Parkinson's disease and diabetes although the underlying mechanisms remain unknown. The aim of this study was to evaluate the effect of type 2 diabetes on Parkinson's disease progression and to correlate neuropathological findings to elucidate pathogenic mechanisms.

METHODS

In this cohort study, medical records were retrospectively reviewed of cases with pathologically confirmed Parkinson's disease with and without pre-existing type 2 diabetes. Time to disability milestones (recurrent falls, wheelchair dependence, dementia and care home placement) and survival were compared to assess disease progression and their risk estimated using Cox hazard regression models. Correlation with pathological data was performed, including quantification of α-synuclein in key brain regions and staging of vascular, Lewy and Alzheimer's pathologies.

RESULTS

Patients with PD and diabetes (male 76%; age at death 78.6 ± 6.2 years) developed earlier falls (p < 0.001), wheelchair dependence (p = 0.004), dementia (p < 0.001), care home admission (p < 0.001) and had reduced survival (p < 0.001). Predating diabetes was independently associated with a two to three-fold increase in the risk of disability and death. Neuropathological assessment did not show any differences in global or regional vascular pathology, α-synuclein load in key brain areas, staging of Lewy pathology or Alzheimer's disease pathology.

CONCLUSIONS

Pre-existing type 2 diabetes contributes to faster disease progression and reduced survival in Parkinson's disease which is not driven by increased vascular, Lewy or Alzheimer's pathologies. Additional non-specific neurodegeneration related to chronic brain insulin resistance may be involved.

A Clinicopathologic Study of Movement Disorders in Frontotemporal Lobar Degeneration

BACKGROUND

Despite the considerable overlap with atypical parkinsonism, a systematic characterization of the movement disorders associated with frontotemporal lobar degeneration (FTLD) is lacking.

OBJECTIVE

The aim of this study is to provide a detailed description of the phenomenology and neuropathologic correlations of movement disorders in FTLD.

METHODS

In this cohort study, movement disorder clinical data were retrospectively collected from medical records of consecutive patients with a postmortem diagnosis of FTLD from the Queen Square Brain Bank between January 2010 and December 2018. At postmortem, neurodegenerative pathologies were systematically evaluated following consensus criteria. Degeneration of the substantia nigra was assessed as a marker of presynaptic dopaminergic parkinsonism using semiquantitative methods.

RESULTS

A total of 55 patients (35 men [64%]) were included with median (interquartile range) age at diagnosis of 58.8 (52.6-63.9) years and a disease duration of 9.6 (6.2-12.9) years. Movement disorders were present in 19 (35%) patients without differences among disease subtypes. The most common syndromes were parkinsonism (9 patients [16%]), usually as an additional late feature, and corticobasal syndrome (CBS, 7 patients [13%]), commonly as a presenting feature. Substantia nigra degeneration was present in 37 (67%) patients although it did not show a good clinical correlation with movement disorders. Those with Pick's disease showed milder substantia nigra degeneration and better response to levodopa.

CONCLUSIONS

Movement disorders can present in all FTLD subtypes, more commonly as a late additional feature (parkinsonism) or as a presenting symptom (CBS). The underlying pathophysiology is complex and likely to involve structures outside the presynaptic striatonigral system. © 2020 International Parkinson and Movement Disorder Society.

Levodopa infusion improves impulsivity and dopamine dysregulation syndrome in Parkinson's disease

BACKGROUND

Impulsivity and dopamine dysregulation syndrome are frequent complications of treatment in Parkinson's disease (PD).

METHODS

We assessed the effect of jejunal levodopa infusion (JLI) on behavioral symptoms in 8 PD patients with motor complications and severe impulsivity and dopamine dysregulation syndrome (DDS), which had not be controlled before by adjusting oral medications. The infusion was delivered during 15 hours (daily dose 1007.2 ± 302.5 mg) and stopped at night time. Patients were reassessed after 25 ± 9 weeks of treatment with a stable dose of jejunal l-dopa.

RESULTS

Off periods and dyskinesias decreased by 27% and 20,7% respectively, compared to baseline. DDS and all types of impulse control disorders (ICDs) improved in all patients, with nearly complete symptom resolution. Punding improved in all 5 patients but disappeared completely in only 1.

CONCLUSIONS

Our experience suggests that l-dopa infusion has a positive effect on both motor complications and behavioral disorders. This treatment approach deserves further controlled studies.