To date, the beta amyloid (Aβ) cascade hypothesis remains the main pathogenetic model of Alzheimer's disease (AD), but its role in the majority of sporadic AD cases is unclear. The “mitochondrial cascade hypothesis” could explain many of the biochemical, genetic, and pathological features of sporadic AD. Somatic mutations in mitochondrial DNA (mtDNA) could
cause energy failure, increased oxidative stress, and accumulation of Aβ, which in a vicious cycle reinforce the mtDNA damage and the oxidative stress. Despite the evidence of mitochondrial dysfunction in AD, no causative mutations in the mtDNA have been detected so far. Indeed, results of studies on the role of mtDNA haplogroups in AD are controversial. In this review we discuss the role of the mitochondria, and especially of the mtDNA,
in the cascade of events leading to neurodegeneration, dementia, and AD.
Mitochondrial DNA (mtDNA) haplogroup-specific polymorphisms were previously related to several neurodegenerative diseases, including Alzheimer's disease (AD). However, the precise role of mtDNA haplogroups in the neurodegenerative cascade leading to AD is still unclear. In this work we have genotyped predefined European mtDNA haplogroups in 209 patients with AD and 191 matched controls. In order to minimise the risk of "genetic contamination", which could lead to false associations between gene markers and disease, we were careful to enrol in the study only patients and controls of clear Tuscan origin (with at least three generations of Tuscanborn relatives). The frequency of the haplogroups did not differ between the two groups, and no correlation with gender, ApoE genotype, age of onset or disease status was observed. Further studies will be required to define the contribution of mtDNA haplogroups, if any, to the pathogenesis of AD. A correct population selection, in order to minimise the risk of genetic contamination, is essential in these studies.
Mitochondrial disorders are caused by impairment of the respiratory chain. Psychiatric features often represent part of their clinical spectrum. However, the real incidence of psychiatric disorders in these diseases is unknown. The aim of this study was to evaluate psychiatric involvement in a group of patients with mitochondrial disorders and without already diagnosed mental illness. Twenty-four patients with mitochondrial disorder and without already diagnosed mental diseases have been studied by means of the mini-international neuropsychiatric interview (MINI) and the newcastle mitochondrial diseases adult scale (NMDAS). In patients with mitochondrial disease, psychiatric conditions were far more common than in general Italian population (about 60 vs. 20-25%), and included major depression, agoraphobia and/or panic disorder, generalized anxiety disorder, social anxiety disorder, psychotic syndromes. Psychiatric involvement did not seem to depend on disease progression. Large, multicenter studies are strongly needed to better characterize the natural history of mitochondrial disorders and of their psychiatric involvement. Moreover, the possibility of mitochondrial diseases should be considered in patients with psychiatric diseases. Finally, we encourage psychiatric evaluation as a routinary approach to mitochondrial patients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.