Relationship Between Non-Cognitive Intrinsic Capacity and Activities of Daily Living According to Alzheimer's Disease Stage

Objective physical function declines in the absence of subjective physical complaints among patients with amnestic mild cognitive impairments and mild alzheimer's disease

PURPOSE

To examine the extent to which patients with amnestic mild cognitive impairment (aMCI) or Alzheimer's disease (AD) perceive their own physical decline.

METHODS

This study included 4450 outpatients (1008 normal cognition [NC], 1605 aMCI, and 1837 mild AD) who attended an initial visit to a memory clinic between July 2010 and June 2021. Their physical function was assessed by the Timed Up and Go test, one-leg standing test, and grip strength. For physical complaints, data were obtained on reports of fear of falling and dizziness or staggering. Logistic regression analysis was performed to compare the patients' physical function and complaints for each stage of NC, aMCI, and mild AD.

RESULTS

Objective physical function declined from aMCI and the mild AD stage, but subjective physical complaints decreased by 20-50% in aMCI and 40-60% in mild AD compared with the NC group.

CONCLUSION

As objective physical functional declined from the aMCI stage onward, subjective physical complaints decreased. This suggests a need for objective assessment of physical function in aMCI and mild AD patients even when they have no physical complaints in the clinical setting.

Digging into the intrinsic capacity concept: Can it be applied to Alzheimer's disease?

Historically, aging research has largely centered on disease pathology rather than promoting healthy aging. The World Health Organization's (WHO) policy framework (2015-2030) underscores the significance of fostering the contributions of older individuals to their families, communities, and economies. The WHO has introduced the concept of intrinsic capacity (IC) as a key metric for healthy aging, encompassing five primary domains: locomotion, vitality, sensory, cognitive, and psychological. Past AD research, constrained by methodological limitations, has focused on single outcome measures, sidelining the complexity of the disease. Our current scientific milieu, however, is primed to adopt the IC concept. This is due to three critical considerations: (I) the decline in IC is linked to neurocognitive disorders, including AD, (II) cognition, a key component of IC, is deeply affected in AD, and (III) the cognitive decline associated with AD involves multiple factors and pathophysiological pathways. Our study explores the application of the IC concept to AD patients, offering a comprehensive model that could revolutionize the disease's diagnosis and prognosis. There is a dearth of information on the biological characteristics of IC, which are a result of complex interactions within biological systems. Employing a systems biology approach, integrating omics technologies, could aid in unraveling these interactions and understanding IC from a holistic viewpoint. This comprehensive analysis of IC could be leveraged in clinical settings, equipping healthcare providers to assess AD patients' health status more effectively and devise personalized therapeutic interventions in accordance with the precision medicine paradigm. We aimed to determine whether the IC concept could be extended from older individuals to patients with AD, thereby presenting a model that could significantly enhance the diagnosis and prognosis of this disease.