Metabolic Syndrome (MetS), which includes diabetes and obesity, is one of the most widespread medical conditions. It is perhaps the leading avoidable cause of premature death. It leads to multi-organ dysfunction over time. MetS has been called a global epidemic by the WHO and is considered a major public health problem.
While the causes of metabolic MetS are complex, high fat diets (HFD), inactive lifestyles, high blood pressure and genetic predispositions are important risk factors. Habitual alcohol and tobacco use also contribute to high blood pressure and to the development of other risk factors in early adulthood, which continue to act in later life. Obesity in conjunction with type 2 diabetes, hypertension, CAD, and dyslipidemia are important features of MetS, which is usually associated with hyperinsulinemia and insulin resistance.
We know how these lifestyle diseases alter our bodies and increase our risks of having many diseases. Rapid changes in diet and lifestyle owing to socioeconomic changes provide added stress causing the exposure of underlying genetic predisposition to chronic diseases such as type 2 diabetes mellitus, obesity, hypertension, CAD, and atherosclerosis.
This in turn raises the incidence of cardiovascular and cerebrovascular diseases. Strokes due to chronic atherosclerosis are preventable. The modification of these lifestyle-related risk factors can lead to primary and secondary prevention of strokes and heart attacks.
The components of metabolic syndrome result in wide-ranging effects, many of which impact the central nervous system (CNS) and result in neurodegenerative diseases linked to the dysfunction of the Blood-brain barrier (BBB). Metabolic syndrome also alters blood pressure and arterial stiffness which, in turn, can damage the BBB. Type 2 diabetes mellitus can result in decreased removal of waste, increased infiltration of the immune cells. Systemic and local inflammation resulting from obesity is a causative factor. Depending on the region of the brain that is affected, this may result in hormonal dysregulation, increased immune sensitivity, disruption of neuronal and glial cells or cognitive impairment. Thus it is very clear that MetS affects cognition and raise the risk for dementia.
Metabolic syndrome is also associated with other chronic diseases affecting liver and kidney functions and this, in turn, has an impact on the nervous system over time. Patients with chronic renal and liver conditions are prone to brain cortical dysfunction and metabolic encephalopathy and this reduces the threshold for seizures. Permanent cognitive impairment is seen in many of these patients.
Since obesity is a component of metabolic syndrome and is quickly becoming one of the most common and debilitating disorders of the developed world, it is important to understand the aetiology of obesity and understand the components of energy balance. Experiments have shown that there is suppression of neuronal turnover leading to increased apoptosis of neurons.
Leptin is a product synthesized in adipocytes/ fat cells and transported through the BBB into the brain. The highest density of leptin receptors is characteristic of the hypothalamus, but they are also detected in the cortex, thalamus, cerebellum, olfactory bulb and choroid plexus. It is often referred to as the “satiety hormone” or the “starvation hormone”. Leptin resistance is characterized by reduced satiety, over-consumption of nutrients, and increased total body mass. This can be countered by interventions such as:
Increased consumption of processed foods (refined carbohydrates, trans-fats, saturated fats) may be associated with obesity, whereas increased intake of omega-3 fatty acids is protective.
The brain thus seems to be integral to energy balance and in turn development of MetS. It is important that we do not get trapped in the vicious cycle of metabolic syndrome.
The causative factors for MetS can be prevented by leading a healthy lifestyle. The elements of this include:
Good health is based on a healthy and nutritious diet. This provides increased protection from diabetes, cancer, heart disease and other chronic non-communicable diseases.
Diet and lifestyle determine your health and in turn your brain health. Maintaining a healthy brain during one’s life is the uppermost goal in pursuing health and longevity. Mind, body and health are interrelated. Fitness of the body is achieved through a healthy diet, exercise and adopting the right habits.
Dr. Bhuvaneshwari Rajendran Senior Consultant – Neurology & Neurophysiology Kauvery Hospital Chennai
