Type 2 Diabetes May Contribute Towards Dementia Development

Malika Ammam, PhD avatar

by Malika Ammam, PhD |

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In a newly published paper in the Neurology journal entitled “Type 2 diabetes mellitus and biomarkers of neurodegeneration”, scientists from Australia found that neurodegenerative disease related dementia could be linked to type 2 diabetes.

Neurodegenerative disorders occur as a consequence of a progressive loss of structure/function of neurons that lead to the death of nerve cells. This results in diseases like dementia, of which the most known form is Alzheimer’s disease. Patients suffering from dementia may experience difficulties dealing with memory loss, language, impaired visual-spatial orientation, lack of attention and loss of problem solving skills. Various causes of the neurodegeneration processes have been pointed out including genetic mutations, aggregation of proteins, membrane damage, accumulation of intracellular toxic proteins, axonal transport, and mitochondrial dysfunction. However, little is known about the mechanisms of action and influence of preexistent medical conditions like diabetes on neurodegenerative processes. This recent study led by Australian scientists shed some insights into the link between type 2 diabetes and dementia.

The team explored whether type 2 diabetes promotes the buildup of amyloid plaque (called β-amyloid) seen in Alzheimer’s disease. The study analyzed data from the US Alzheimer’s Disease Neuroimaging Initiative which involved 816 people with an average age of 74 years. Among those, 397 suffered from mild cognitive impairment which is a precursor to dementia, 191 with Alzheimer’s disease dementia, 124 had diabetes, and 228 people had no memory/thinking problems.

The scientists looked at associations between type 2 diabetes and parameters like thickness of the outer brain layer, brain amyloid plaque, body fluid found in the brain (called cerebrospinal fluid or CSF) as well as microtubule protein (called tau). In total 816 patients were tested by brain magnetic resonance imaging (MRI), 102 patients were screened for brain amyloid imaging and 415 were checked for CSF as well as amyloid plaque and tau measurements.

The team found that type 2 diabetes was associated with lower thickness of the outer brain layer and greater CSF total tau protein. Higher levels of tau in CSF could reflect substantial build-up of plaques in the brain, which may contribute to the development of dementia.

In sum, the scientists concluded that type 2 diabetes might be a promoter in neurodegenerative processes independently of diagnosis of Alzheimer’s disease dementia. In other words, patients with diabetes may have a higher probability of developing dementia. The underlying mechanism of action could be related to the tau protein, which is imperative to understand for future therapies aimed at reducing damage/death of brain cells.