Final answer:
Brain shrinkage in late adulthood can vary per individual but typically includes a decline in cognitive functions and sensory abilities. The brain decreases in volume by roughly 5% per decade after age 40, with increases in this rate possible after age 70. Maintaining a healthy lifestyle can help mitigate the effects of brain shrinkage.
Step-by-step explanation:
As humans age, particularly when they reach late adulthood, which starts from the 60s onward, the brain undergoes physical changes. Although significant neural complexity increases and brain efficiency improves during adolescence, by the age of six, the brain has reached about 90% of its adult size.
During late adulthood, there are observable declines in sensory abilities and cognitive functions – issues such as memory loss, dementia, and Alzheimer's disease may present themselves. Over time, the brain can lose mass, which is sometimes referred to as brain shrinkage or atrophy.
This process can lead to a reduction in cognitive abilities, though each person's experience with brain aging can be different. It's important to note the claim that humans only use 10 percent of their brains is a myth; our brains are highly active, even during simple tasks.
The exact amount of brain shrinkage by age 70 can vary widely among individuals. Factors influencing brain atrophy include genetics, lifestyle, and overall health. While there is no universal measurement for how much the brain shrinks by a specific age, studies indicate that, on average, the brain's volume decreases by about 5% per decade after the age of 40. This rate of decline may increase after age 70, but again, this is highly individual.
In late adulthood, the loss of neuronal connections, a process known as synaptic pruning, continues, but at a much slower pace compared to earlier life stages. Some of the changes can be attributed to the normal aging process, but others might be exacerbated by health conditions. Therefore, maintaining a healthy lifestyle that includes regular physical and mental exercise can help to reduce the effects of brain shrinkage.