DOI: 10.1002/alz.075521 ISSN: 1552-5260

Associations between normal cognitive aging and neurodegeneration

Mathilde Suhr Hemminghyth, Monica Haraldseid Breitve, Arvid Rongve, Luiza J. Chwiszczuk, Tormod Fladby, Bjørn‐Eivind Kirsebom
  • Psychiatry and Mental health
  • Cellular and Molecular Neuroscience
  • Geriatrics and Gerontology
  • Neurology (clinical)
  • Developmental Neuroscience
  • Health Policy
  • Epidemiology



Multiple cognitive domains, including learning, memory and psychomotor speed, show significant reductions with age. These changes are thought to reflect normal cognitive aging. However, since cerebrospinal fluid (CSF) neurodegenerative biomarkers, such as total‐tau (t‐tau) and Neurofilament light chain (NfL), also show age‐related increases in normal aging, we aimed to investigate whether age‐associated cognitive decline may be mediated by age‐associated neurodegenerative changes.


We included 114 cognitively healthy participants aged 40‐80 years from The Norwegian Dementia Disease Initiation Study. All had normal concentrations of CSF Aβ42/40 ratio. Cognitively healthy was defined as demographically adjusted T‐scores ≥35 on standardized cognitive tests. We fitted mediation models using structural equation modelling (SEM), with either CSF NfL or t‐tau as a mediator between age and CERAD learning, CERAD recall, TMT‐A and TMT‐B. All variables were standardized prior to analyses; in addition, both t‐tau and NfL were log transformed due to skewness.


See table 1 for demographic and clinical characteristics. Whilst neither NfL nor t‐tau showed statistically significant mediation of age‐related cognitive decline, our results nevertheless suggest a partial mediation of NfL on age‐related cognitive decline. Here, relationships between age and CERAD learning, CERAD Recall, and TMT‐A performance were weakened whereas higher NfL was associated with worse performance, in particular for delayed memory recall. This was not observed for t‐tau in any models. See figure 1‐2.


Age‐related decline in verbal learning, memory and psychomotor speed may be partially attributable to NfL‐associated neurodegenerative changes in cognitively healthy adults. As NfL reflects axonal degeneration, these results may reflect white matter neurodegeneration in aging.

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