Alzheimer disease and genetics: anticipating the questions

Systemic mitochondrial dysfunction and the etiology of Alzheimer's disease and down syndrome dementia

Increasing evidence is implicating mitochondrial dysfunction as a central factor in the etiology of Alzheimer's disease (AD). The most significant risk factor in AD is advanced age and an important neuropathological correlate of AD is the deposition of amyloid-beta peptide (Abeta40 and Abeta42) in the brain. An AD-like dementia is also common in older individuals with Down syndrome (DS), though with a much earlier onset. We have shown that somatic mitochondrial DNA (mtDNA) control region (CR) mutations accumulate with age in post-mitotic tissues including the brain and that the level of mtDNA mutations is markedly elevated in the brains of AD patients. The elevated mtDNA CR mutations in AD brains are associated with a reduction in the mtDNA copy number and in the mtDNA L-strand transcript levels. We now show that mtDNA CR mutations increase with age in control brains; that they are markedly elevated in the brains of AD and DS and dementia (DSAD) patients; and that the increased mtDNA CR mutation rate in DSAD brains is associated with reduced mtDNA copy number and L-strand transcripts. The increased mtDNA CR mutation rate is also seen in peripheral blood DNA and in lymphoblastoid cell DNAs of AD and DSAD patients, and distinctive somatic mtDNA mutations, often at high heteroplasmy levels, are seen in AD and DSAD brain and blood cells DNA. In aging, DS, and DSAD, the mtDNA mutation level is positively correlated with beta-secretase activity and mtDNA copy number is inversely correlated with insoluble Abeta40 and Abeta42 levels. Therefore, mtDNA alterations may be responsible for both age-related dementia and the associated neuropathological changes observed in AD and DSAD.

Early onset dementia: clinical and social aspects

BACKGROUND

Increasing efforts are being devoted to the study of early onset dementia (EOD), namely dementia in persons under the age of 65. Until recently, it was assumed that dementia occurs primarily among people aged 65 and over. However, since the number of persons with EOD is increasing, its importance as a clinical and social problem is rising accordingly. The aim of the present paper is to summarize research in this area.

METHODS

We reviewed the research published to date on EOD, and divided the current body of knowledge into several main sections.

RESULTS

The first section focuses on clinical aspects and summarizes findings regarding prevalence, causes, symptoms, diagnosis, and management of persons with EOD. The second section focuses on social aspects related to the cost of care for young people with the disease, the challenges faced by individuals and caregivers, and the services available for this population. Finally, conclusions and future directions are suggested.

CONCLUSIONS

Research on EOD is still in its early stages. There is an urgent need to expand research that will lead to more effective diagnosis and management of EOD as well as to the allocation of funds and the development of appropriate services suitable for the unique needs of young people with dementia.

Alzheimer disease in women: a clinical and genetics perspective

Upon completion of this activity, the learner will be able to: 1. Identify clinical and genetic characteristics and considerations associated with Alzheimer disease (AD). 2. Describe assessment and management strategies for AD. 3. Describe nursing implications for women and families with, or at risk for, AD.