Incidence of dementia in oldest-old with amnestic MCI and other cognitive impairments

Abstract

Objective: To examine the incidence of dementia among the oldest-old people with normal cognition and different types of cognitive impairment.Methods: This study included 395 participants without dementia (mean age 93.3 years) from The 90ϩ Study, a prospective, population-based study of aging and dementia in people aged 90 years and older. The participants had evaluations for dementia every 6 months, and their average follow-up was 2.5 years. We examined the incidence of all-cause dementia in participants stratified into 4 cognitive groups: normal, amnestic mild cognitive impairment (aMCI), nonamnestic mild cognitive impairment (naMCI), and other cognitive impairment (OCI).Results: Dementia incidence was highest for participants with aMCI (31.4% per year) and OCI (39.9% per year). Participants with naMCI had an incidence of 14.1% per year, and participants with normal cognition had an incidence of 8.4% per year. Dementia incidence was associated with increasing age in both normal and cognitively impaired participants; however, an APOE4 allele was associated with a higher dementia incidence only in participants with baseline cognitive impairment. Conclusions:The risk of developing dementia in the oldest-old is high and increases to higher rates when cognitive impairment is present. Similar to results of studies in younger elderly individuals, cognitive impairment and increasing age were related to increased dementia incidence. High dementia incidence rates in the oldest-old individuals, particularly when cognitively impaired, emphasize the need to further study cognitive impairment and dementia in this rapidly expanding age group. Neurology Less than 1% of people aged 65-70 years develop dementia each year, 1 and incidence approximately doubles with every 5 years of increasing age.2 A previous study of the current cohort 3 found that the doubling of incidence extends to ages 90 and older (the oldest-old), with 13% of 90-to 94-year-old, 21% of 95-to 99-year-old, and 41% of 100-year-old individuals developing dementia each year. Hence, dementia incidence is very high in the oldest-old, the fastest growing age group in the United States. 4Compared with normal individuals, cognitively impaired individuals, particularly those with memory impairments, have an increased risk of developing dementia. Population studies have found that approximately 6%-15% of 80-year-old individuals with mild cognitive impairment (MCI) develop dementia each year compared with 1%-2% per year of elderly individuals with normal cognition.5-8 Few studies have examined dementia incidence in oldest-old individuals with different types of cognitive impairment.This study examined the incidence of dementia in the oldest-old stratified into 4 groups: normal, amnestic mild cognitive impairment (aMCI), nonamnestic mild cognitive impairment

Neuropsychological Criteria for Mild Cognitive Impairment in the Framingham Heart Study’s Old-Old

“…Similar findings in The 90+ Study showed that amnestic MCI conferred a greater risk for all-cause dementia than non-amnestic MCI; however, non-amnestic MCI was nevertheless significantly associated with dementia [24]. Approximately 74% of individuals diagnosed with dementia in the current sample were diagnosed with probable AD.…”

Prevalence of Apolipoprotein E Polymorphisms in Alzheimer’s Disease, Mild Cognitive Impairment, and Healthy Elderly: A Northern Greece Study

“…On the other hand, the ε3/2 genotype had a protective profile by decreasing the odds for AD by 71.0 and 61.0% for men and women respectively ( Table 5). The investigation of the APOE effect stratified by gender presents controversial results in literature: some studies present men to have a higher AD risk [32,45], while others are at the expense of the above statement, finding women at greater risk than men [46,47]. According to literature, although men may have a higher risk of MCI [48], women are disproportionally affected with AD.…”

The Cache County Study on Memory in Aging: Factors affecting risk of Alzheimer's disease and its progression after onset

“…The Cardiovascular Health Study (CHS) reported that 51% of their Mild cognitive Impairment (MCI) sample converted to dementia over a mean follow-up of 4.3 years (approximately 12% annually; (Lopez et al, 2007)). Among very old individuals in the 90+ Study, the annual dementia incidence rate varied by MCI subtype: amnestic MCI was nearly 40% per year and nonamestic MCI was 14% per year (Peltz et al 2011). …”