Children of Alzheimer Patients: An Overview

181 Children whose parents receive a diagnosis of Alzheimer’s disease (AD) spend much of their adult lives anticipating the possibility of receiving that diagnosis themselves. Their number is unknown, but considering the estimated AD prevalence (4.5 million in the United States in 2000; http://www.alz.org/AboutAD/statistics.asp) and projections that the number of Americans suffering from this devastating disease could range from 8 to 16 million by the year 2050, many more offspring will be at risk and know that they are at risk unless scientific advances alter the disease incidence and progression. There is a scarcity of published information on children of AD patients, which is surprising in view of their rapidly increasing number and the fact that so many of them are so deeply concerned about their risk of developing AD. Considering the value of AD offspring for the study of AD both from a genetic and nongenetic perspective and the unexpected preliminary results of a 20-year follow-up of a small group of AD offspring, a 2-day conference was organized in March 2005 (see the appendix). Together, participants explored current knowledge concerning early detection of vulnerability to AD, specifically with reference to adult children of parents with AD. The objective was to examine what we know, what we need to know, and how to obtain the needed information most expeditiously and cost-effectively, using whenever possible already existing databases. All of the articles in this issue of the Journal of Geriatric Psychiatry and Neurology (JGPN) derive from presentations at that conference. Numerous studies have indicated that the risk of dementia increases exponentially with age, from less than 1% in those younger than 65 years to between 25% and 50% for those older than 85, with 50% to 90% of dementia due to AD. According to a meta-analysis integrating estimates from 18 epidemiological studies on AD, 5.7% of Americans older than 65 have AD, and the age-specific prevalence rate rises from 1.1% at 65 to 69 years to 4.6% at 75 to 79 years, 17.8% at 85 to 89 years, and 52.5% at 95 years. In a recent collaborative study carried out in 8 European countries, the pooled AD incidence rate rose from 1.2 at age 65 to 69 years to 9.1 at 75 to 79 and 35.3 at age 85 to 89 per 1000 person-years. Therefore, concern about developing AD is probably widespread among middle-aged adults in general and children of AD patients in particular. AD, already the third most costly disease to treat in the United States (following only cancer and heart disease) may well become one of the most significant challenges to the health of Americans in the first half of the 21st century. The burden imposed on society is reflected in the 54.4% expected increase of Medicare costs between 2000 and 2010 (from $31.9 to $49.3 billion) and Medicaid expenditures on residential dementia care increasing 80% (from $18.2 to $33 billion). The burden of care, physical, social, psychological, and financial, borne by families is difficult to measure, and children are second only to spouses in caring for AD patients. Because AD is a slowly progressing disease that over the course of years relentlessly robs its victims of the higher mental functions characteristic of human beings, children watch their parents’ declining memory and verbal and mathematical skills; they observe their parents’ executive dysfunction, disorientation, confusion, and aphasia; and they witness the behavioral, psychological, and sleep disturbances, depression, psychosis, aggression, and agitation that are among the hallmark changes turning AD patients into shadows of their former selves. Even though detrimental effects of caregiver stress have been described, the role of stress as a risk factor specifically for AD has not as yet been established but may exceed that for cancer caregivers. One might hypothesize that the depressive symptoms so often associated with caregiver stress increase the vulnerability of adult children with an AD parent by activating mechanisms yet to be established that link depression and AD. Several other risk factors for AD have been firmly established; they include chronological age, genetic relationship to a person with AD, and carrying the apolipoprotein E e4 allele (APOE-e4). Advancing age is by far the most important risk factor for AD. Family history, too, is a critical risk factor for AD and especially important to the children of AD patients. The disease has been found in all ethnic groups examined to date, in men as well as women. Some differences have been reported for various ethnic groups, but data are relatively scarce. Three genes, the so-called Alzheimer genes, have been identified as causes of early-onset familial AD. They are inherited in a fully penetrant autosomal dominant manner so that those Children of Alzheimer Patients: An Overview