Relationship Between Diabetes and Cognitive Impairment Based on Olfactory Function Assessment and Functional MRI

The Cross-sectional and Longitudinal Study of Relationship Between Diabetes and Cognitive Impairment by Olfactory Function Assessment and Functional MRI in Obese and Normal Weight Diabetic Patients

The purpose of this study is to explore the relationship between diabetes and cognitive impairment by olfactory function assessment and functional MRI.

Previous research has shown both obesity and diabetes are associated with an increased risk of cognitive impairment. Meanwhile, olfactory impairment is associated with incident (amnestic mild cognitive impairment) aMCI and progression from aMCI to (Alzheimer disease) AD dementia. On one hand, in the cross-sectional study, biometric measurements, cognitive assessment, olfactory function and fMRI results are analysed to explore the differences among T1DM patients, T2DM patients and non-diabetic people . One the other hand, in the longitudinal study, changes in olfactory function and fMRI results in diabetic and non-diabetic obese patients both at baseline and 6 months after their bariatric surgery are collected to investigate whether better glucose and weight control benefit brain function.

Inclusion Criteria:

1. Have a certain level of education (at least 6 years), able to complete the cognitive assessment;
2. Disease duration >1 year.

Exclusion Criteria:

1. Control participants would be excluded if they had a fasting blood glucose level >7.0 mmol/L; glucose level> 7.8 mmol/L after oral glucose tolerance test (OGTT);
2. Montreal Cognitive Assessment (MoCA,Beijing edition) score of < 20;
3. History of neurologic or psychological illness;
4. History of cardiovascular or cerebrovascular disease;
5. Abnormal results of thyroid hormones, vitamin B12, and folate.
6. Metal implants, unable to complete the MR examinations or evidence of cortical infarcts, hemorrhage, or structural brain disease other than atrophy, lacunes, or white matter lesions;
7. Left-handed;
8. Partial or complete olfactory dysfunction associated with sinusitis,allergic rhinitis, and deviated nasal septum.