We retrospectively analysed myocardial MIBG images acquired with a dual-head gamma camera and low-energy high-resolution collimator (LEHR) in 194 patients with suspected synucleinopathy or atypical parkinsonism, including 34 with genetic Parkinson's disease (PD; 4 PARK1, 8 PARK2 and 22 PARK8), 85 with idiopathic PD (iPD), 6 with idiopathic REM sleep behaviour disorder (iRBD), 17 with dementia with LB (DLB), 40 with multiple system atrophy (MSA) and 12 with progressive supranuclear palsy (PSP), and in 45 healthy controls.
Mutations in <i>LRRK2</i>, which encodes leucine-rich repeat kinase 2, are the most common genetic cause of familial and sporadic Parkinson's disease (PD), a degenerative disease of the central nervous system that causes impaired motor function and, in advanced stages, dementia.
These data suggest that an increased susceptibility to mitochondrial calcium dysregulation contributes to dendritic injury in mutant LRRK2 pathogenesis.<b>SIGNIFICANCE STATEMENT</b> Cognitive dysfunction and dementia are common features of Parkinson's disease (PD), causing significant disability.
The LRRK2-PD presented less frequent subjective cognitive complaints (18.5% vs. 63.0%, p = 0.002), and mild cognitive impairment or dementia (25.9% vs. 59.2%, p = 0.027).
In conclusion, significant differences were not detected between R1441G-PD and i-PD in cognitive, depression and anxiety scales, or PD-MCI and PD-Dementia prevalence, and the cognitive profile was identical in the two groups.
The clinical features of LRRK2-associated with PD in our patients were similar to those of idiopathic PD although most LRRK2 mutated patients presented with bradykinesia instead of tremor; 33.3% developed dementia.
In contrast, α-synuclein accumulation in Lewy bodies defines a spectrum of disorders ranging from typical late-onset PD to PD dementia and including sporadic and autosomal dominant PD forms due to mutations in SCNA and LRRK2.
It seems that genetic Parkinson's disease variants in which Lewy bodies are the prominent pathological hallmark - such as in PARK1, PARK4 and PARK8 - dementia is part of the phenotype.
To determine if LRRK2 mutations might be involved in frontotemporal dementia (FTD), 5 individuals with multiplex familial FTD kindreds and 41 pathologically confirmed cases of FTD, including 23 with a family history of dementia, were screened for genetic variations in the LRRK2 gene.
Therefore, the LRRK2 mutation has a relatively high frequency in the AJ population, is not fully penetrant for parkinsonism in the elderly, and does not appear to be commonly associated with late-onset dementia.