The Analyze Blog

Obesity and Hippocampal Atrophy

By AnalyzeDirect Staff, last updated March 17, 2016

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Obesity_and_Hippocampal_AtrophyRecent data shows that worldwide obesity has more than doubled since 1980. In 2014, almost 2 billion adults were overweight and of these, over 600 million were obese (World Health Organization). Evidence indicates that obesity is not only a major risk factor for conditions such as cardiovascular diseases, diabetes, and musculoskeletal disorders, but also a concern for brain health.

It is therefore pivotal to further investigate how obesity is linked to the onset and development of these diseases, especially those regarding cerebral health. To this effect, scientists from the Australian National University, Canberra, decided to explore associations between obesity and the hippocampus in ageing. 

The sample of their longitudinal study included 420 participants aged 60-64 years who all underwent MRI brain scans over an 8-year follow-up. From the MRI images, hippocampal volume was determined by manually tracing the region of interest using Analyze software. The team examined correlations between Body Mass Index (BMI), a measure of body fat based on height and weight, and hippocampal volume change over time. The researchers found that higher BMI was associated with smaller hippocampal volume at the first assessment. With time, these subjects experienced greater hippocampal atrophy compared to those with lower BMI. In fact, obese participants experienced a significant atrophy of 2% above that observed in individuals with healthy BMI over the follow-up period.

Previous animal and human studies have shown that adipose tissue is responsible for the production and upregulation of pro-inflammatory molecules, such as circulating cytokines. These signaling proteins play a crucial role in decreased neurogenesis and increased neurodegeneration, which together lead to smaller brain volumes, particularly of the hippocampus.

Altogether, these findings support the causal relationship between obesity and the hippocampal atrophy encountered in this study. These results provide further evidence that obesity may cause neurodegeneration in ageing. And, the conclusions draw attention to the need to find healthy solutions for people struggling with being overweight or obese.

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