Brain oxidative stress and cognitive function in older adults with diabetes and pre-diabetes who are at risk for dementia

Camilla M Hoyos; Stephen Colagiuri; Ashlee Turner; Catriona Ireland; Sharon L Naismith; Shantel L Duffy

doi:10.1016/j.diabres.2021.109178

Brain oxidative stress and cognitive function in older adults with diabetes and pre-diabetes who are at risk for dementia

Diabetes Res Clin Pract. 2022 Feb:184:109178. doi: 10.1016/j.diabres.2021.109178. Epub 2021 Dec 24.

Authors

Camilla M Hoyos¹, Stephen Colagiuri², Ashlee Turner³, Catriona Ireland³, Sharon L Naismith⁴, Shantel L Duffy⁵

Affiliations

¹ The University of Sydney, Faculty of Science, School of Psychology, Sydney, New South Wales, Australia; The University of Sydney, Brain and Mind Centre, Sydney, New South Wales, Australia; Woolcock Institute of Medical Research, Centre for Sleep and Chronobiology, The University of Sydney, Sydney, New South Wales, Australia. Electronic address: camilla.hoyos@sydney.edu.au.
² The University of Sydney, Charles Perkins Centre, Sydney, New South Wales, Australia; The University of Sydney, Faculty of Medicine and Health, The Boden Collaboration for Obesity, Nutrition, Exercise and Eating Disorders, Sydney, New South Wales, Australia.
³ The University of Sydney, Faculty of Science, School of Psychology, Sydney, New South Wales, Australia; The University of Sydney, Brain and Mind Centre, Sydney, New South Wales, Australia.
⁴ The University of Sydney, Faculty of Science, School of Psychology, Sydney, New South Wales, Australia; The University of Sydney, Brain and Mind Centre, Sydney, New South Wales, Australia; The University of Sydney, Charles Perkins Centre, Sydney, New South Wales, Australia.
⁵ The University of Sydney, Brain and Mind Centre, Sydney, New South Wales, Australia; The University of Sydney, Charles Perkins Centre, Sydney, New South Wales, Australia; The University of Sydney, Faculty of Medicine and Health, Sydney, New South Wales, Australia.

PMID: 34958845
DOI: 10.1016/j.diabres.2021.109178

Abstract

Aims: Diabetes is an established risk factor for dementia. This study aimed to examine the relationship between various cognitive domains, brain oxidative stress and markers of diabetes in older adults at risk for dementia.

Methods: Older adults at risk for dementia underwent comprehensive neuropsychological and medical assessment. At risk was defined as those with subjective and/or objective cognitive impairment. Pre-diabetes and type 2 diabetes were defined using American Diabetes Association definitions for fasting blood glucose and HbA1c. Brain oxidative stress as indicated by glutathione (GSH) was assessed via magnetic resonance spectroscopy in the anterior cingulate cortex.

Results: One-hundred and forty-seven older adults completed a neuropsychological assessment and fasting blood sample with 63 also undergoing magnetic resonance spectroscopy. Those with pre-diabetes/diabetes according to FBG had impaired memory retention, set-shifting and response inhibition, compared to those with normal blood glucose. In contrast, there were no significant differences in any cognitive outcome using the HbA1c definition. Increasing glucose and HbA1c levels were associated with reduced GSH concentration in the anterior cingulate.

Conclusions: This study demonstrates that in older adults at risk for dementia, having pre-diabetes or diabetes is associated with impaired memory and executive dysfunction. It also highlights the potential role of oxidative stress as a pathophysiological mechanism that may underpin the link between diabetes and cognitive dysfunction.

Keywords: Cognition; Glutathione; Glycaemic function; Mild cognitive impairment; Oxidative stress; Subjective cognitive impairment.

MeSH terms

Aged
Brain
Cognition / physiology
Cognitive Dysfunction*
Dementia* / etiology
Diabetes Mellitus, Type 2* / complications
Humans
Neuropsychological Tests
Oxidative Stress
Prediabetic State* / complications