It is important to first understand obesity and dementia. The World Health Organization (WHO) defines overweight and obesity as an abnormal or excessive fat accumulation that presents a risk to health. At present the most common way of measuring obesity is BMI - Body mass index is a simple calculation of weight in kgs/height in m2. A BMI of 25+ is considered overweight and a BMI of 30+ is considered obese.
Dementia is not a single disease but a collective term for memory loss or impairment, thinking and communication. It is a comprehensive loss of memory with reduced cognitive and intellectual performance due to damaged brain cells.
There are various studies that link obesity to dementia, the reasons for impaired cognitive function are increased fat content that reduces the amount of blood supply to the brain that could possibly result in an ischemia resulting in loss of memory, obese individuals also tend to have a higher amount of adipokines that reduce white matter in the brain. Both the decrease in the vascular supply to the brain and reduction in white matter can cause brain atrophy resulting in loss of normal brain function.
Another factor that links obesity and dementia is insulin resistance, the brain requires insulin for cognitive development, deficiency of insulin due to insulin resistance which is very common amongst obese individuals can cause lack of insulin transfer from the peripheral nervous system to the brain leading to dementia. However, the results of these studies are conflicting, some studies say that higher BMIs later in life actually lowers the risk of dementia.
BMI calculates overall fatness and could often be misleading, as it does not take into consideration waist circumference. Recent studies associate waist circumference, also known as visceral obesity or abdominal obesity to higher rates of dementia rather than just overall obesity itself. Visceral Obesity is one of the major risk factors for inflammation and insulin resistance which are precursors for developing diabetes. All of these factors together have shown to cause deterioration of cognition.
In fact, mid-life obesity has shown to be a greater risk factor for developing dementia later in life.
Simply put there is enough evidence stating that obesity - Overall or central are risk factors for developing dementia later in life, thus stressing on the importance of leading healthy a lifestyle with correct nutrition and physical activity to maintain a healthy weight and prevent cognitive decline in future.
Dr. Muffazal Lakdawala, Founder & Chief Surgeon – Digestive Health Institute by Dr. Muffi