Final answer:
A known biological marker for Alzheimer's disease is Pittsburgh Compound B (PiB), which binds to amyloid plaques in the brain and could be used to detect AD early. For Huntington's Disease, genetic testing can identify the causative gene mutation. Additionally, researchers are seeing potential in other early symptoms and biomarkers for AD in fluids like blood and cerebrospinal fluid.
Step-by-step explanation:
Yes, there is a biological marker that is a good indicator of HD (Huntington's Disease) exposure, and researchers are also exploring biomarkers for Alzheimer's disease (AD). Specifically, a radiolabeled chemical known as Pittsburgh Compound B (PiB) is a promising marker that binds to amyloid plaques in the brain. PiB, in combination with brain imaging techniques, could potentially detect early signs of AD, however it does not specifically indicate HD exposure. Scientists are also looking for biomarkers in bodily fluids that might suggest the presence of AD earlier.
Additionally, they are investigating early symptoms, like changes in movement or smell, for their potential to predict AD. In the context of heart disease, the serum LDL:HDL ratio is recognized as a strong predictor of risk. In connection to Huntington's Disease (HD) specifically, genetic testing can identify the gene mutation responsible for HD, giving an almost certain predictive indicator of an individual's risk. This is different from AD, where genetic tests might identify susceptibility but not certainty of disease occurrence.