The nervous system controls almost all your actions—sending messages from the brain throughout your body to regulate your thoughts, movements, cognition, involuntary responses, and different physiological processes. Like other body systems, the nervous system is not immune to the effects of aging.
Many age-related conditions negatively impact the function, health, and integrity of components of the nervous system like the brain, spinal cord, or nerve endings. Prioritizing health-promoting habits aimed at extending your healthspan—or years spent in generally good health free of disease—helps to maintain optimal nerve functioning with age. And for those who are really looking to fine-tune their health, there are evidenced-based habits you can implement to optimize cognitive function to keep you sharp and mentally active in your 60s, 70s, 80s, and beyond.
Let’s dive into the physiological structure of the nervous system and how aging and age-related conditions impact its structure and functioning.
What is the nervous system?
The nervous system is the body’s command center, consisting of the brain, spinal cord, and nerves. Neurons or nerve cells help the nervous system carry out bodily functions by transmitting, or sending, signals to other neurons and the brain.  The nervous system influences all areas of health—detecting, regulating, and managing the body’s responses to changes in internal and external environments. It affects breathing, movement, heart rate, the senses, digestion, sleep, learning, memory, thinking, and feeling, among other processes. 
What are the different parts of the nervous system?
Statins are medications that manage and treat high cholesterol by lowering LDL, triglyceride, and total cholesterol levels and raising the concentration of HDL cholesterol. Statins inhibit the enzyme hydroxymethylglutaryl-CoA reductase (HMG-CoA), which decreases liver production of cholesterol, especially ApoB-containing lipoproteins (ApoB) and encourages more LDL cholesterol to be removed from circulation and brought into the liver for excretion. 
The central nervous system
The central nervous system (CNS) includes the brain and spinal cord. The CNS receives information from the rest of the body, analyzes and processes it, and determines an appropriate response.
The brain controls movement, sensation, emotions, responses, communication, thought processing, and memory. The spinal cord carries information to the brain from sensory organs. And it sends commands away from the brain to the peripheral organs. [1,3,4]
The peripheral nervous system
The peripheral nervous system consists of the nerves that branch from the spinal cord to reach all parts of the body. It is divided into the efferent (motor) and afferent (sensory) divisions. The afferent division sends signals from the peripheral organs to the CNS. The CNS then relays a message via the efferent division to the peripheral organs to carry out an action and cause an effect. 
The efferent division
The efferent division can be subdivided into the somatic and autonomic nervous systems.
Somatic nervous system: The somatic nervous system controls muscles and sensory organs such as the eyes, ears, mouth, and skin. 
Autonomic nervous system: The autonomic nervous system is the automatic or involuntary system. It innervates internal organs and affects cardiac muscle, smooth muscle, and glandular epithelium (cells that form glands, organs that produce substances, such as hormones, milk, sweat, and tears). 
The autonomic nervous system regulates countless body processes, including blood pressure, heart and breath rates, body temperature, digestion, metabolism, and water and electrolyte balance, among other functions. 
The autonomic nervous system consists of the sympathetic, parasympathetic, and enteric nervous systems.
- The parasympathetic nervous system: This system’s functions include slowing heart rate, dilating blood vessels, and relaxing the digestive tract muscles.
- The sympathetic nervous system: This division is responsible for the “fight or flight” response in stressful situations requiring energy expenditure. Activation of this system increases heart rate and breaks down stored nutrients to provide energy to power you for a “fight or flight” situation. 
- The enteric nervous system: This division is localized to the gastrointestinal tract and can function independently from the other two divisions of the autonomic nervous system. 
Most of the time, the divisions of the autonomic system work together, but sometimes they can exert opposing effects on the same target. For example, both affect blood vessels: the parasympathetic division decreases blood pressure while the sympathetic division increases blood pressure.
How does aging affect the nervous system?
Aging causes physiological changes to the nervous system, leading to slower processing speeds of information and greater difficulty with multitasking. Aging alters connections between neurons, causing changes in perception, cognition, processing, and mobility. Additionally, aging weakens synapses (where neurons connect and transfer signals), so more effort and focus are required to process tasks, negatively affecting cognitive ability. However, routine memory, skills, and knowledge should remain stable with normal aging. [6,7]
What steps can you take to maintain a healthy nervous system?
Establishing healthy lifestyle habits can help preserve nervous system functioning and cognitive performance.
How much you sleep can affect your nervous system. Moreover, there may be an optimal amount of sleep to strive for to benefit cognition. Seven to eight hours of sleep may be the sweet spot for retaining cognitive function. [8,9]
Routine Vipassana meditation—a practice that focuses on remaining in the moment without judgment, evaluation, or emotional responses—may improve cognitive control and response inhibition. 
Maintain a healthy diet
The Mediterranean-DASH (Dietary Approach to Systolic Hypertension) Intervention for Neurodegenerative Delay or MIND Diet is an eating pattern associated with slower declines in cognitive function. The MIND diet encourages a healthy dietary pattern, emphasizing green leafy vegetables, nuts, berries, legumes, whole grains, fish, poultry, and olive oil, foods that protect brain health. 
Eat more dark leafy greens
Consuming one serving per day of green leafy vegetables—one-half cup cooked or one cup raw greens—may help stave off cognitive decline. Dark leafy green vegetables contain a plethora of nutrients that benefit cognition. In particular, they contain,
- Phylloquinone: a form of vitamin K synthesized exclusively by plants
- Folate: a B vitamin essential for DNA synthesis and brain function
- Lutein: A type of carotenoid with antioxidant properties
These nutrients seem to play a crucial role in protecting against and slowing cognitive decline. 
Exercise is one of the best interventions to maintain a healthy nervous system and improve cognitive function. Just 30-minute daily bouts of moderate-intensity physical activity can boost cognitive performance. [13, 20] And long-term regular exercise may protect neurons by enhancing DNA repair processes and reducing oxidative stress. 
Age-related conditions can impact the nervous system
While there are lifestyle habits you can implement to retain optimal brain health and cognition with aging, there are several age-related or chronic conditions that can also have a profound effect on the nervous system. These disorders have an array of causes—genetic, lifestyle, environmental, or congenital abnormalities—treatment plans, and impacts on the nervous system.
Here’s a brief overview of how common age-related disorders affect the nervous system.
Dementia is an all-encompassing term that describes the impaired ability to remember, think, pay attention, communicate, problem-solve, or make decisions related to everyday life that impacts a person’s quality of life. While many people cite feelings of forgetfulness with age, dementia is not a normal component of aging. 
Alzheimer’s disease is an irreversible, progressive form of dementia resulting in the loss of memory, thinking, and the ability to do simple tasks. Alzheimer’s is characterized by the loss of nerve cells and accumulation of amyloid plaques (proteins that clump together and disrupt cell function) that twist and tangle to form neurofibrillary tangles in the brain. These changes affect the transmission of signals throughout the nervous system and lead to damage and the death of nerve cells in areas of the brain responsible for memory, language, reasoning, and social behavior. 
The exact cause of Alzheimer’s disease is unclear. However, multiple factors likely contribute to the development of Alzheimer’s, and some research considers genetics, inflammation, oxidative stress, and the accumulation of DNA damage to play a role in the disease’s pathology. 
Parkinson’s disease is a movement disorder that occurs due to the death or impairment of neurons in the brain, particularly those producing dopamine, a chemical that helps neurons communicate). This decrease in dopamine production causes difficulty with movement, tremors, stiffness, and impaired balance ensue. 
Mild forgetfulness—such as forgetting someone’s name or occasionally misplacing your keys—can be a normal part of aging, as the speed of signaling between neurons slows. But memory loss may indicate a bigger issue when it becomes more consistent and affects perception and the ability to problem solve or carry out activities of daily living. Struggling with paying attention and increased confusion can also be signs of a more serious nervous system problem than just what is typically associated with aging. 
For people with both type 1 and type 2 diabetes, chronically elevated blood sugar levels can lead to diabetic neuropathy (nerve damage) causing pain or tingling in different areas of the body, especially the fingers and toes—and affecting communication throughout the nervous system. Poor blood sugar control, including both high and low levels of blood sugar, is associated with cognitive decline, and people who have type 2 diabetes are also at an increased risk of dementia and Alzheimer’s.
And evolving research suggests type 2 diabetes and Alzheimer’s disease share similar pathways, prompting discussions as to whether Alzheimer’s disease is type 3 diabetes. [20,21]
Atherosclerosis is the accumulation of plaque (fat deposits) within the arteries, causing them to harden and blood vessels to narrow. This results in the delivery of less oxygen and nutrients throughout the body, and increases the risk of heart attack and stroke, as brain cells deteriorate without oxygen.
Coronary artery calcium (CAC) scores measure plaque in the arteries and are used to assess the risk of coronary artery disease. One systematic review found that higher CAC scores were associated with worse memory, speech, language, and executive functioning. And a higher CAC score is linked to a higher risk of developing dementia and cognitive impairment. 
- The nervous system includes the brain, spinal cord, and nerves. It is responsible for transmitting signals between the brain and the rest of the body to regulate physiological processes.
- Aging slows communication between neurons and the brain and can result in the death of brain and nerve cells.
- Often, age-related conditions that affect the nervous system can lead to impaired cognition, memory, and perception and, in some cases, may result in behavioral changes.
- Sleeping seven to eight hours, practicing Vipassana meditation, consuming a healthy diet full of leafy green vegetables, and regularly exercising can improve cognition and slow age-related decline in nervous system functioning.
[14 ] https://www.sciencedirect.com/science/article/pii/S0197458021002402?via%3Dihub