Final answer:
Twin studies indicate that Alzheimer's disease is influenced by heredity, with genetic factors playing a significant role, especially noted in the presence of certain genetic mutations such as the APOE gene variant E4.
Step-by-step explanation:
Twin studies suggest that Alzheimer's disease is influenced by heredity. Alzheimer's disease is characterized by progressive neuronal death leading to memory loss and dementia. While environmental factors can influence the risk and progression of the disease, twin studies have demonstrated a strong genetic component, particularly in the more common late-onset form of the disease. One gene that has been identified is the apolipoprotein E (APOE) gene, where the E4 variant increases the likelihood of developing Alzheimer's. Additionally, research has uncovered other genes that may be involved in disease pathology.
Though a small percentage of Alzheimer's cases are due to mutations in specific genes causing Familial Alzheimer's Disease (FAD), the majority are sporadic with no known direct cause. Both types of Alzheimer's exhibit similar brain pathology such as amyloid plaques and neurofibrillary tangles. Current research continues to explore the genetic underpinnings of Alzheimer's disease, with recent discoveries providing new clues about potential genetic risk factors.