BBC has reported that brain shrinkage is unique to the human brain and does not effect our closest evolutionary relatives, chimpanzees. Currently, humans are the only known animals to suffer from age-related dementia, which is directly related to the shrinkage of our brains.
By age 80, the average human brain has lost 15% of its original weight. Scientists have determined that the weight loss is associated with the decline of neurons and in the connections between them. This decline also affects the brain’s ability to process thoughts and memories.