Conversion to dementia from mild cognitive disorder: the Cache County Study

OBJECTIVE

To examine 3-year rates of conversion to dementia, and risk factors for such conversion, in a population-based sample with diverse types of cognitive impairment.

METHODS

All elderly (aged 65 or older) residents of Cache County, UT, were invited to undergo two waves of dementia screening and assessment. Three-year follow-up data were available for 120 participants who had some form of mild cognitive impairment at baseline. Of these, 51 had been classified at baseline with prodromal Alzheimer disease (proAD), and 69 with other cognitive syndromes (CS).

RESULTS

Three-year rates of conversion to dementia were 46% among those with cognitive impairment at baseline. By comparison, 3.3% without impairment converted to dementia in the interval. Among converters, AD was the most common type of dementia. In individuals with at least one APOE epsilon4 allele, those with proAD or CS exhibited a 22- to 25-fold higher risk of dementia than cognitively unimpaired individuals (vs 5- to 10-fold higher risk in those without epsilon4).

CONCLUSIONS

Individuals with all types of mild cognitive impairment have an elevated risk of dementia over 3 years, more so in those with an APOE epsilon4 allele. These results suggest value in dementia surveillance for broad groups of cognitively impaired individuals beyond any specific category, and utility of APOE genotyping as a prognostic method.

A population-based study of the association between coronary artery bypass graft surgery (CABG) and cognitive decline: the Cache County study

BACKGROUND

The relationship between coronary artery bypass graft (CABG) surgery and cognitive decline remains uncertain, in particular with regard to whether there is delayed cognitive decline associated with this procedure.

METHODS

This was a population-based cohort study involving participants in the Cache County Study of Memory Health and Aging. At baseline the study enrolled 5,092 persons age 65 and older and followed them up three years later and again four years after that. Individuals who reported having undergone CABG surgery at study baseline or had this surgery in between follow-up waves were compared to individuals who never reported having the surgery. The main outcome measure was the Modified Mini Mental State (3MS). Multilevel models were used to examine the relationship between CABG surgery and cognitive decline over time.

RESULTS

Study participants who had CABG surgery evidenced 0.95 points of greater decline relative to baseline on the 3MS at the first follow-up interview after CABG, and an average of 1.9 points of greater decline at the second follow-up interview, than those without CABG (t = -2.51, df = 2,316, p = 0.0121), after adjusting for several covariates, including number of vascular conditions. This decline was restricted to individuals who were more than five years past the procedure and was not evident in the early years after the surgery.

CONCLUSIONS

CABG surgery is associated with accelerated cognitive decline more than five years after the procedure in a long-lived population. This decline is small and its clinical significance is uncertain. We could not find an association between CABG and decline in the first five post-operative years.

A population study of Alzheimer's disease: findings from the Cache County Study on Memory, Health, and Aging

There are several population-based studies of aging, memory, and dementia being conducted worldwide. Of these, the Cache County Study on Memory, Health and Aging is noteworthy for its large number of "oldest-old" members. This study, which has been following an initial cohort of 5,092 seniors since 1995, has reported among its major findings the role of the Apolipoprotein E gene on modifying the risk for Alzheimer's disease (AD) in males and females and identifying pharmacologic compounds that may act to reduce AD risk. This article summarizes the major findings of the Cache County study to date, describes ongoing investigations, and reports preliminary analyses on the outcome of the oldest-old in this population, the subgroup of participants who were over age 84 at the study's inception.

Three-year incidence of first-onset depressive syndrome in a population sample of older adults: the Cache County study

OBJECTIVE

Estimates of incidence of late-life depression vary greatly with few studies excluding demented cases through in-depth evaluation and most studies failing to control for the effect of mortality and interval treatment. In a large population-based study, the authors examined the effect on incidence of first-onset depressive syndrome to determine whether any gender or age differences in incidence are attenuated with inclusion of these additional measures.

METHOD

Incidence rates of depressive syndrome per 1,000 person-years are presented for 2,877 nondemented elderly (ages 65 to 100 years) residents of Cache County, Utah. Cases are identified by direct interview methods, by inference from prescription antidepressant medicine use, and by postmortem informant interview for decedents.

RESULTS

In-person interviews yielded incidence rates of first-onset depressive disorder (any type) of 13.09 for men and 19.44 for women. Inclusion of antidepressant users increased these figures to 15.55 for men and 23.30 for women. Addition of postmortem interview data yielded rates of 20.66 for men and 26.29 for women. Individuals with no history of depression had rates for major depression of 7.88 for men and 8.75 for women; minor depression rates were 19.23 for men and 24.46 for women (p = 0.691; effect for minor depression p <0.0001). Age did not predict incidence.

CONCLUSIONS

Incidence of first-onset major depression varies with data source and prior lifetime history of depression. Gender effects apparent in interview data are attenuated when postmortem information and pharmacotherapy were considered.

Population-based study of medical comorbidity in early dementia and "cognitive impairment, no dementia (CIND)": association with functional and cognitive impairment: The Cache County Study

OBJECTIVE

Authors investigated medical comorbidity in persons with dementia and "Cognitive Impairment, No Dementia" (CIND).

METHODS

The Cache County Study is an ongoing population-based study of the epidemiology of dementia, the risk factors for conversion from CIND to dementia, and the progression of dementia. As part of the study's first incidence wave, persons with dementia (N=149), CIND (N=225), or without cognitive impairment (N=321) were identified and studied. Participants received comprehensive clinical evaluations and were rated on the General Medical Health Rating (GMHR), a global measure of seriousness of medical comorbidity. Participants and informants also completed the Mini-Mental State Exam and provided self-report information about comorbid medical conditions and functioning in activities of daily living.

RESULTS

There were few differences in number or type of comorbid medical conditions between persons with CIND and dementia, but persons with dementia were prescribed more medications. Stroke was more common in dementia participants, but other illnesses common in old age were not significantly different across cognitive groups. Medical comorbidity was more serious in both dementia and CIND, such that both groups were less likely to have "little to no" comorbidity. Seriousness of medical comorbidity was significantly associated with worse day-to-day functioning and cognition.

CONCLUSIONS

Persons with CIND and dementia have more serious medical comorbidity than comparable persons without cognitive impairment. This comorbidity may play a role in the progression of CIND and dementia. Future studies should investigate the role of medical comorbidity and its treatment on dementia onset or progression, as well as the mechanisms mediating its neuropathologic effects.