Abstract

Although type 2 diabetes mellitus (T2DM) is a well-recognized risk factor for dementia, the neural mechanisms that underlying cognitive impairment in T2DM remain unclear. We used functional magnetic resonance imaging (fMRI) during a computerized version of the Iowa Gambling Task to investigate the neural basis of decision making at the initial onset stage of T2DM. Eighteen newly diagnosed middle-aged T2DM patients, with no previous diabetic treatment history, and 18 matched controls were recruited. Results indicated that T2DM patients made more disadvantageous decisions than controls. Compared to healthy subjects, T2DM patients showed decreased activation in the ventral medial prefrontal cortex (VMPFC), orbitofrontal cortex (OFC) and anterior cingulate cortex, and increased activity in the dorsolateral prefrontal cortex, posterior cingulate cortex, insula and occipital lobes. IGT performance positively correlated with changes in brain activation in the VMPFC and OFC in both groups. Moreover, poor glycemic control was associated with decision-making function both in behavioral and brain activity in the VMPFC and OFC in patients. Conclusively, T2DM patients may suffer from weaknesses in their prefrontal cortex functions that lead to poorer decision-making under ambiguity, at least as assessed by the IGT.

Highlights

  • Type 2 diabetes mellitus (T2DM) is s a common metabolic disease characterized by hyperglycemia due to insulin resistance and relative insulin deficiency

  • Our present study provided the first neuropsychological evidence that primary onset middle-aged type 2 diabetes mellitus (T2DM) patients exhibited altered patterns of brain activation during the Iowa Gambling Task

  • They showed less activation in the ventral medial prefrontal cortex (VMPFC), orbitofrontal cortex (OFC) and anterior cingulate cortex (ACC), and greater activation in the right dorsolateral prefrontal cortex (DLPFC), insula, posterior cingulate cortex and occipital lobes when compared to controls

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Summary

Introduction

Type 2 diabetes mellitus (T2DM) is s a common metabolic disease characterized by hyperglycemia due to insulin resistance and relative insulin deficiency. In the IGT, rules for gains and losses are implicit and the subject must balance probabilistic outcomes and variable magnitudes of reward/punishment under unclear conditions. They have to consider the benefit of decisions for their current living situation, and to anticipate the consequences of a decision in the near and far future. Decision-making evaluated by the IGT has been described in a variety of neurological disorders such as MCI11, Alzheimer’s disease[12,13,14], type 1 diabetes mellitus[15], Parkinson’s disease[16, 17] and multiple sclerosis[18,19,20]. Few studies have employed the IGT in functional magnetic resonance imaging (fMRI) investigations in neurological patients[16], and no study to date has been published regarding decision making on the IGT in T2DM patients

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