Higher Risk of Cognitive Decline Among Obese Type 2 Diabetes Patients

Overweight and obese individuals who are in the initial stages of type 2 diabetes had more severe abnormalities associated with brain structure as well as cognition when compared to patients with normal weight. This study highlights the importance of maintaining a healthy weight among people with diabetes, with the study published in the journal Diabetologia. Dr. Sunjung Yoon and Dr. In Kyoon Lyoo from South Korea’s Ewha Brain Institute at the Ewha Women’s University, along with scientists from the US, studied the relevance of weight on the cognitive function of the brain among people with early stage type 2 diabetes.

Type 2 Diabetes

Individuals with type 2 diabetes are known to have an increased health risks that affect the various organs of the body. This disease affects the brain and leads to cognitive dysfunction which leads to a risk of dementia. Though the dementia is known, the exact mechanism associated with the development of this condition has not been fully determined.

• Type 2 diabetes has been shown to be associated with obesity, with obese individuals at a heightened risk of developing the condition.
• Overweight individuals are at an increased risk of developing metabolic diseases.
• Metabolic diseases can lead to alterations in the brain and increase the abnormalities associated with type 2 diabetes.

Effect of Obesity on Brain Function among Early Type 2 Diabetics

The study participants included were -

• 150 Koreans who were between 30 and 60 years of age.
• 50 individuals with early stage type 2 diabetes were overweight or obese.
• 50 individuals with early stage type 2 diabetes were at a normal weight.
• 50 individuals who were taken as control and who had a normal weight and did not have type 2 diabetes.

All the study participants across the three groups were age and sex matched. Study participants with type 2 diabetes had been diagnosed within 5 years of the study and were not on insulin therapy.

Studying the Effect on Brain

Magnetic Resonance Imaging (MRI) was used to study the structure of the brain of the study participants. The mean thickness of the cerebral cortex was recorded to understand the changes in brain structure.

Cognitive tests included -

• Psychomotor speed
• Memory test
• Executive function

These aspects of cognitive function are known to affect people with type 2 diabetes

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The study findings showed that -

• The gray matter of the brain was significantly thinner in clusters in the motor and occipital cortices, temporal and prefrontoparietal regions of the brains among study participants with diabetes compared to the control.
• The gray matter was also thinner among the motor and temporal cortices among study participants who were overweight or obese.
• There were changes in specific regions of the brain that showed that there was vulnerability of the temporal lobe when associated with type 2 diabetes and obesity.

Association with Dementia

Earlier studies have shown that individuals who have type 2 diabetes have an increased risk for dementia. Similarly overweight or obese individuals are also known to develop dementia. Moreover, alterations in the temporal lobe have been shown to be associated with Alzheimer’s Disease. The changes that were observed in the temporal region in the current study are an indication of the mechanism of development of dementia among individuals who have type 2 diabetes and are overweight.

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Association of BMI and Higher Risk of Type 2 Diabetes Among Asians

The current classification of weight status- overweight or obese as determined by Body Mass Index (BMI), prescribed by WHO, are the same for all ethnicities.

• People of Asian origin are sensitive to even small variations in BMI and have a higher risk of type 2 diabetes.
• This could be attributed to increased insulin resistance, even among lean individuals.

There is a need for early interventional strategies for overweight or obese people with type 2 diabetes in order to protect the structure of the brain and prevent cognitive decline.

Type 2 Diabetes

Diabetes is a condition in which the body has high blood sugar levels (hyperglycemia). Type 2 diabetes is a common form of diabetes and is caused when the body does not utilize insulin sufficiently, called insulin resistance. Initially, the pancreas synthesize extra insulin but then there is a deficiency of insulin which leads to higher blood sugar levels.

Cognitive Decline and Type 2 Diabetes

In a study titled ‘Cognitive Dysfunction and Diabetes Mellitus’ and published in the journal Endocrinology Reviews, by Christopher T. Kodl and Elizabeth R. Seaquist, Individuals who had type 2 diabetes were found to be associated with the following cognitive impairment

• Reduction in psychomotor speed
• Alterations in processing speed
• Lowered frontal lobe/executive function
• Changes in working memory
• Poor verbal memory
• Complexity in motor functioning
• Inability to recall events immediately
• Reductions in verbal fluency
• Poor visual retention
• Lack of attention

The current study has highlighted the relevance of being overweight or obese and cognitive impairment among individuals with type 2 diabetes, stressing the need for interventional strategies that lower blood sugar levels and strategies to lower the BMI of the individual, before cognitive decline.

References:

1. Sujung Yoon et al. Brain changes in overweight/obese and normal-weight adults with type 2 diabetes mellitus, Diabetologia (2017). DOI: 10.1007/s00125-017-4266-7
2. Type 2 Diabetes - (http://www.diabetes.org/diabetes-basics/type-2)
3. Cognitive Dysfunction and Diabetes Mellitus - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2528851/)

Source-Medindia