Neuroscientists believed that humans were born with a certain number of neurons that die little by little with age. When a neuron dies, it is lost permanently. However, according to new research, the neurotransmitter dopamine can promote the birth of new neurons in adults. So there is hope after all! It is a simple fact that the human brain changes as a person ages. Over time, our brain’s volume and weight diminishes. As a matter of fact, we lose ten percent of our brain’s weight between the ages twenty and ninety; but age is not the only factor that triggers brain shrinkage.