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Dementia in Parkinson's disease is associated with enhanced mitochondrial complex I deficiency
Author(s) -
Gatt Ariana P.,
Duncan Olivia F.,
Attems Johannes,
Francis Paul T.,
Ballard Clive G.,
Bateman Joseph M.
Publication year - 2016
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.26513
Subject(s) - mitochondrial dna , dementia , mitochondrial biogenesis , parkinson's disease , mitochondrion , mitochondrial respiratory chain , dementia with lewy bodies , mitochondrial disease , biology , medicine , mitochondrial myopathy , endocrinology , pathology , disease , biochemistry , gene
ABSTRACT Background Dementia is a common feature of Parkinson's disease (PD), but the neuropathological changes associated with the development of Parkinson's disease dementia (PDD) are only partially understood. Mitochondrial dysfunction is a hallmark of PD but has not been studied in PDD. Methods Molecular and biochemical approaches were used to study mitochondrial activity and quantity in postmortem prefrontal cortex tissue. Tissues from pathologically confirmed PD and PDD patients and from age‐matched controls were used to analyze the activity of mitochondrial enzyme complex nicotinamide adenine dinucleotide:ubiquinone oxidoreductase, or complex I (the first enzyme in the mitochondrial respiratory chain), mitochondrial DNA levels, and the expression of mitochondrial proteins. Results Complex I activity was significantly decreased (27% reduction; analysis of variance with Tukey's post hoc test; P < 0.05) in PDD patients, and mitochondrial DNA levels were also significantly decreased (18% reduction; Kruskal‐Wallis analysis of variance with Dunn's multiple comparison test; P < 0.05) in PDD patients compared with controls, but neither was significantly reduced in PD patients. Overall, mitochondrial biogenesis was unaffected in PD or PDD, because the expression of mitochondrial proteins in patients was similar to that in controls. Conclusions Patients with PDD have a deficiency in mitochondrial complex I activity and reduced mitochondrial DNA levels in the prefrontal cortex without a change in mitochondrial protein quantity. Therefore, mitochondrial complex I deficiency and reduced mitochondrial DNA in the prefrontal cortex may be a hallmark of dementia in patients with PD. © 2016 International Parkinson and Movement Disorder Society