What have we learned from cognition in the oldest-old

Area of Science:

• Gerontology
• Neurology
• Pathology

Background:

• The population segment over 90 is rapidly expanding, exhibiting the highest dementia prevalence.
• Understanding dementia and cognitive function across all age groups is crucial.

Purpose of the Study:

• To review recent findings on dementia and cognition in the oldest-old population.
• To provide insights into the factors influencing dementia risk and resilience in advanced age.

Main Methods:

• Review of recent scientific literature on dementia in individuals over 90.
• Analysis of risk factors, pathologies, and resilience mechanisms in the oldest-old.

Main Results:

• Alzheimer's disease (AD) risk factors vary by age; hypertension may be protective in the oldest-old.
• Non-AD pathologies (e.g., microinfarcts, hippocampal sclerosis, TDP-43) account for at least half of dementia cases in this group.
• Brain pathology load correlates with dementia risk and severity, yet many oldest-old individuals exhibit resilience.
• Resilience to AD pathology may be linked to the absence of other pathologies; AD biomarkers have limited utility in this demographic.

Conclusions:

• Studies on dementia in the oldest-old are vital for advancing understanding and developing interventions for dementia across all ages.
• The complex interplay of pathologies and resilience factors in the oldest-old necessitates further research for effective dementia prevention and treatment strategies.