what happens to the brain as an individual grows older?

a. what happens to the billions of nerve cells in the cortex as one becomes older?

b. will the dead neurons be replaced?

c. why is memory affected as one grows old?

Read, read, read ...

http://www.psychologytoday.com/blog/memory-medic/201211/what-happens-the-aging-brain

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2596698/

http://www.google.com/search?q=will+the+dead+neurons+be+replaced&oq=will+the+dead+neurons+be+replaced&aqs=chrome..69i57.1422j0j7&sourceid=chrome&es_sm=119&ie=UTF-8

http://www.google.com/?gws_rd=ssl#q=why+is+memory+affected+as+one+grows+old

a. As an individual grows older, there are several changes that occur in the brain, particularly in the cortex. The cortex is responsible for various cognitive functions such as memory, attention, language, and executive functions. Some changes that happen to the billions of nerve cells (neurons) in the cortex include:

1. Loss of neurons: With age, there is a gradual loss of neurons in certain brain regions, including the cortex. This loss can affect the overall structure and functioning of the brain.

2. Changes in connectivity: As one ages, the connections between neurons may become weaker or less efficient, leading to slower information processing and communication within the brain.

3. Changes in neurotransmitter levels: The levels of certain neurotransmitters, which are essential for communication between neurons, can also change with age. For example, there may be reduced levels of neurotransmitters like dopamine and serotonin, which can impact cognitive function.

b. Generally, dead neurons are not replaced in the adult human brain. Unlike other cells in the body, neurons have a limited capacity to regenerate. Therefore, if a neuron dies, it is not usually replaced by a new one. However, neighboring neurons can sometimes compensate for the loss by forming new connections or altering their functioning patterns.

c. Memory can be affected as one grows older due to various factors. Some reasons for age-related memory decline include:

1. Structural and functional changes: The physical changes in the brain, such as loss of neurons and weaker connections, can contribute to memory deficits. These changes can affect the ability to form new memories and retrieve stored information.

2. Reduced neurotransmitter levels: As mentioned earlier, the levels of certain neurotransmitters decline with age. Since neurotransmitters are involved in memory processes, reduced levels can impair memory formation and recall.

3. Health conditions: Aging increases the risk of developing various health conditions, such as cardiovascular diseases, diabetes, and neurodegenerative disorders like Alzheimer's disease. These conditions can impact memory function directly or indirectly.

4. Lifestyle factors: Certain lifestyle factors, such as lack of physical activity, poor sleep, chronic stress, and unhealthy diet, can also contribute to age-related memory decline.

It is important to note that although memory changes are common with aging, not everyone experiences significant memory impairments. Factors such as genetics, overall health, and lifestyle choices can influence the extent and rate of memory decline.