A study published in Diabetes, Obesity, and Metabolism has found that a high basal metabolic rate (BMR) could indicate cognitive impairment and memory loss.
A high BMR also increases the iron deposits in brain cells, leading to neurodegeneration, reveal Australian researchers of the study.
BMR indicates how energy is used to keep the body’s functions – like breathing, heartbeat, maintaining body temperature, and processing nutrients – going. Sedentary lifestyles, ageing, unhealthy food habits, and stress can cause BMR fluctuations.
“Metabolic syndrome is a common term for the disorder caused by different risk factors in an individual,” says Dr Ajay Kumar Maini of Moti Hospital, Agra.
Factors such as high cholesterol levels, renal dysfunction, abnormal liver enzyme levels, cardiovascular problems, obesity, blood pressure and nutritional deficiencies contribute to different BMRs. A high BMR can lead to metabolic syndromes such as diabetes, thyroid, and atherosclerosis, he adds.
Earlier studies have conjectured that BMR – which is the rate at which the body burns calories – could cause neurodegenerative disorders like Alzheimer’s and Parkinson’s. However, the exact link between BMR and neurodegeneration has not been clear.
Lead author of the present study, Dr Amanda Lumsden, and her team investigated this link further. In 2022, the study examined brain scans and blood tests from the health records of 26,239 people. For this, it selected people in the age group of 37-73 years based on gender, age, smoking habits, physical exercise routines, and having no history of dementia or stroke.
The participants were put into six groups based on 39 metabolic biomarkers related to heart, diabetes, kidney and liver function, bone and joints, growth hormone, obesity, blood pressure, and BMR. The researchers analysed their brain MRI scans using machine learning methods to identify the risk of dementia.
The team wanted to see if different blood factor values have a corresponding change in the brain structure. Based on earlier research studies, then it focussed on four brain areas:
- grey matter volume – related to overall cognition
- hippocampal volume: this region within the grey matter is related to memory formation
- white matter hyper-intensities as a measure of brain lesions or damage
- iron accumulation in the deep region of the brain called caudate; this has been linked to Alzheimer’s disease
Dr Lumsden, who is from the University of South Australia, explains that “Amongst 39 metabolic biomarkers, basal metabolic rate (BMR) showed the most striking association with brain MRI measures.”
“Our research will add a new layer to the understanding of brain health,” she says in a statement.
She adds that BMR was associated with lower hippocampal volume, lower overall grey matter volume, and higher levels of iron accumulation.
Researchers also observed a few aspects in this study:
- Young people, non-smokers, and those with a healthy lifestyle routine had a healthy brain structure compared to older and smoking individuals.
- Iron accumulation in the brain was higher in older people surveyed and those who smoked. (Iron accumulation increases with age).
- A higher BMR affected the brain structures adversely, as observed in the MRI scans.
- Individuals with high triglycerides, high BMI, poor liver and kidney function, high levels of inflammation, and lower vitamin D experienced adverse effects on the brain structure.
“Our study suggests that these biomarkers could be used to identify the risk of dementia. Still, the basal metabolic rate may be a better indicator of brain iron accumulation than obesity,” says Dr Lumsden. More research study is needed to understand the link between these MRI brain measures with BMR, she adds
As per Dr Maini, “BMR directly impacts the consumption of oxygen in the brain which is necessary for healthy brain functioning.” However, it is different for everyone, he adds.
Dr Lumsden says iron is the most abundant metal in our body, and is vital to produce energy, neurotransmitters, myelin (protective sheath of neurons), oxygen transport, and many other fundamental processes. Too little or too much iron deposition in the brain can be detrimental to health.
