Energy Balance in Huntington's Disease. A Multidisciplinary Study Approach for a Complex Problem (BEHD-EM)

In the last decade, numerous studies have been published showing how epigenetic (environmental) factors can modify the clinical manifestations of diseases of genetic origin. Specifically, epidemiological studies have observed that physical exercise delays the onset and slows down the progression of neurodegenerative diseases (dementia, Parkinson's disease, HD), by producing, between the different mechanisms, greater plasticity of the different neuronal circuits. Another environmental factor such as nutrition has also been highlighted by numerous authors, highlighting the role of the Mediterranean diet in delaying the onset, especially in Parkinson's disease, as the phenolic components of olive oil produce an inhibition of the Pathological aggregation of modified alpha synuclein. On the contrary, it has been seen that an energy deficit at the cellular level accelerates the neurodegeneration process, shortening survival in different animal models.

To maintain an adequate energy balance, it is required that the energy expenditure produced by physical activity (GAF), plus the expenditure produced by the maintenance of the different organs: energy expenditure at rest (GAR) and thermogenesis, is similar to the input of energy produced by the oxidation of macronutrients from food intake. In HD, it is believed that this energy balance is not adequate, either due to the decrease in food intake (very frequent when there are swallowing problems), and the decrease in physical activity produced by alterations in mobility, or by structural damage (hypothalamic, mitochondrial) produced by the neurodegeneration process per se. When the energy balance is negative (energy expenditure> caloric intake), due to a decrease in intake or due to sustained involuntary physical activity (chorea), it can lead to the use of other energy substrates such as adipose tissue and muscle, triggering sarcopenia, cachexia, and ultimately, accelerating the neurodegeneration process. Weight loss and a low body mass index (BMI) in patients with neurodegenerative diseases lead to a greater development of neurological symptoms, while a high food intake has been associated with a more rapid progression in the symptoms of these patients. For all these reasons, it seems that nutrition plays a determining role, the dietary and nutritional analysis being fundamental.

To date, there are very few studies on energy balance in neurodegenerative diseases, addressing it from a comprehensive point of view and analysing each of its contributing components (energy expenditure-caloric intake). A better knowledge of the energy balance in HD may lead to the development of non-pharmacological, easily accessible and cost-effective therapeutic strategies such as lifestyle modifications, through adequate physical activity and nutritional intake.