A survey of a centenarian population in Italy, focusing on self-sufficiency and cognition

Neuropsychological Test Performance of Cognitively Healthy Centenarians: Normative Data From the Dutch 100-Plus Study

OBJECTIVES

The fraction of the population that reaches the age of 100 years is growing. At this age, dementia incidence is high and cognitive functioning is highly variable across individuals. Normative data for neuropsychological tests are lacking in centenarians, which hampers the ability to evaluate their cognitive functioning for both research and clinical practice. Here, we generated norms for neuropsychological tests in a sample of cognitively healthy centenarians while taking sensory impairments into account.

DESIGN

Cross-sectional cohort study.

SETTING

Centenarians who participate in the prospective 100-plus Study.

PARTICIPANTS

A total of 235 centenarians (71.5% female), who self-reported to be cognitively healthy, which was confirmed by an informant and a trained researcher.

MEASUREMENTS

We generated normative data for 15 cognitive tests, measuring global cognition (Mini-Mental State Examination [MMSE]), premorbid intelligence, attention, language, memory, executive function, and visuospatial function by multiple linear regressions and/or by reporting percentiles.

RESULTS

Normative data for global cognition resulted in a mean MMSE score of 25.6 ± 3.1 (range = 17-30; interquartile range = 24-28). Vision problems and fatigue often complicated the ability to complete tests, and these problems explained 41% and 22% of the missing test scores, respectively. In contrast, hearing problems (4%) and task incomprehension (6%) rarely complicated test performance. While educational level was associated with performance on the majority of the tests, sex and age were only weakly associated with test performance.

CONCLUSIONS

We generated normative data for 15 common neuropsychological tests in a large sample of cognitively healthy centenarians, while taking age-related sensory impairments into consideration. These normative data allow the detection of deficits across a wide range of cognitive domains. Our results suggest that, next to education level, vision ability and the level of fatigue should be taken into account when evaluating cognitive functioning in centenarians. J Am Geriatr Soc 67:759-767, 2019.

The 100-plus Study of cognitively healthy centenarians: rationale, design and cohort description

Although the incidence of dementia increases exponentially with age, some individuals reach more than 100 years with fully retained cognitive abilities. To identify the characteristics associated with the escape or delay of cognitive decline, we initiated the 100-plus Study (www.100plus.nl). The 100-plus Study is an on-going prospective cohort study of Dutch centenarians who self-reported to be cognitively healthy, their first-degree family members and their respective partners. We collect demographics, life history, medical history, genealogy, neuropsychological data and blood samples. Centenarians are followed annually until death. PET–MRI scans and feces donation are optional. Almost 30% of the centenarians agreed to post-mortem brain donation. To date (September 2018), 332 centenarians were included in the study. We analyzed demographic statistics of the first 300 centenarians (25% males) included in the cohort. Centenarians came from higher socio-economic classes and had higher levels of education compared to their birth cohort; alcohol consumption of centenarians was similar, and most males smoked during their lifetime. At baseline, the centenarians had a median MMSE score of 25 points (IQR 22.0–27.5); most centenarians lived independently, retained hearing and vision abilities and were independently mobile. Mortality was associated with cognitive functioning: centenarians with a baseline MMSE score ≥ 26 points had a mortality percentage of 17% per annual year  in the second year after baseline, while centenarians with a baseline MMSE score < 26 points had a mortality of  42% per annual year (p = 0.003). The cohort was 2.1-fold enriched with the neuroprotective APOE-ε2 allele relative to 60–80 year-old population controls (p = 4.8 × 10⁻⁷), APOE-ε3 was unchanged and the APOE-ε4 allele was 2.3-fold depleted (p = 6.3 × 10⁻⁷). Comprehensive characterization of the 100-plus cohort of cognitively healthy centenarians might reveal protective factors that explain the physiology of long-term preserved cognitive health.