Alzheimer's disease is primarily caused by the abnormal build-up of two proteins in and around brain cells: amyloid and tau. Amyloid deposits form plaques around brain cells, while tau deposits create tangles inside brain cells. These protein accumulations disrupt normal brain function, leading to the death of brain cells and shrinkage of brain areas, especially those responsible for memory

. The exact trigger for this protein build-up is not fully understood, but it begins many years before symptoms appear. Alongside this, there is a decrease in neurotransmitters, particularly acetylcholine, which is important for communication between brain cells

. Several factors increase the risk of developing Alzheimer's disease:

• Age: The most significant risk factor; the likelihood doubles every 5 years after age 65. Early-onset Alzheimer's can affect people from around age 40

• Genetics: Family history and specific genes, such as APOE4, can increase risk. In rare cases, Alzheimer's is caused by a single inherited gene

• Down's syndrome: People with Down's syndrome have a higher risk due to genetic changes that promote amyloid plaque build-up

• Head injuries: Severe head trauma may increase risk, though research is ongoing

• Cardiovascular health: Conditions like smoking, obesity, diabetes, high blood pressure, and high cholesterol increase risk, likely due to their effects on brain blood supply

• Other factors: Hearing loss, untreated depression, social isolation, sedentary lifestyle, and environmental factors such as air pollution and metal toxicity may also contribute

In summary, Alzheimer's disease results from a complex interplay of abnormal protein accumulation in the brain, genetic predisposition, aging, and lifestyle or environmental factors