The Cheat Sheet on Aging, part 1

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100 Ways that Our Bodies Change with Age, part 1

The Senses

1. High frequency hearing loss is very common and develops earlier and at a higher rate in men.   An early sign is difficulty hearing the human voice clearly. Ask people to speak more slowly or to rephrase what they are saying to you.
2. Elders are more likely to develop earwax impaction in the ear canals.  This occurs because earwax hardens and is less likely to fall out of the ear on its own.
3. The sense of smell deteriorates, particularly after age 50.  Most people over age 80 cannot smell things very well. The ability to taste food is then affected because smell and taste are closely linked.
4. The lens of the eye becomes less elastic, more rigid and more opaque with age.  These changes make it more difficult to focus on close objects. In addition, the older eye adapts more slowly to changes in lighting conditions and is more sensitive to glare.
5. Dry eye syndrome is common in older women and can present with dryness, blurred vision, eye irritation, a foreign body sensation, a gritty feeling or a burning sensation in the eyes.  First line treatment is over the counter lubricant eye drops (which can be used several times throughout the day) and lubricant eye ointments which may be applied at bedtime.

The Skin

1. Sun exposure accounts for 80% of skin aging.  Both UVA and UVB radiation damage the skin but many sunscreens on the market do not offer adequate protection from UVA radiation.  Good UVA blockers include zinc oxide, titanium oxide, avobenzone and ecamsule. Look for at least one of these active ingredients in your broad spectrum UVA/UVB sunscreen.  Sunscreen should be applied to all sun exposed areas every day you go outside.
2. Beside sunscreen, topical retinoids such as tretinoin (prescription) and adapalene (now available as Differin gel) are the best way to prevent and treat skin aging.  Most retinoids are deactivated by sunlight and must be applied at night. Retinoids should be used nightly for maximum benefit. They may be mildly irritating at first so it’s best to start by applying a few times a week and then applying more frequently as tolerated.
3. Dry skin becomes very common, especially in the winter months.  Dry skin is also a top cause of itchy skin. Daily use of moisturizer will make your skin feel and look better.
4. There are 3 types of moisturizers:  occlusives, humectants and emollients.  The goal of a moisturizer is to increase the water content in the top layer of skin (stratum corneum).  An occlusive moisturizer can do this by coating the stratum corneum (SC) to slow water loss (examples: petroleum jelly, lanolin, mineral oil, jojoba oil, olive oil).  A humectant moisturizer gets water into the SC by attracting water from the atmosphere and from the skin layer below called the dermis (examples: glycerin, urea, lactic acid, glycolic acid).  Lastly, emollients moisturizers soften and smooth the top layer of skin. Many occlusive moisturizers are also emollients.
5. Urea 20% cream is one of the best moisturizers for the very dry, thickened and calloused skin of the feet.

The Face

1. Facial aging occurs in all layers of the face, not just the skin.  The 5 layers of the face from top to bottom are: the skin, subcutaneous fat pads, muscles of facial expression, connecting ligaments and finally, the deep fat pads and bone.  
2. A common change in the facial bones is the enlargement of the eye sockets.
3. The aging face loses volume due to shrinking deep fat pads and changes in the shape of the skull.  
4. Sagging of the superficial fat pads causes formation of nasolabial folds, puffy under eye bags and jowls.  The superficial fat pads sag because they lose support from underlying structures such as the retaining ligaments.
5. Dark undereye circles which appear on a daily basis after age 30 are often due to thinning of the skin and loss of fat in the undereye area (known as the tear trough abnormality).  The volume loss under the eyes causes a depression to form between the lower border of the bony eye socket and the cheek mass below.
6. Below the eyebrows, loss of skin elasticity and subcutaneous fat causes the skin of the upper eyelids to sag (called dermatochalasis).

The Heart

1. The structure of our four- chambered heart changes with age:  the 2 upper chambers dilate, the wall of the main pumping chamber (the left ventricle) thickens and some heart cells die off and are replaced by scar tissue.
2. The main artery carrying blood from the heart (called the aorta) dilates, becomes stiffer and less compliant.  This is one reason why blood pressure tends to go up with age. The aorta is less able to expand and contract to accommodate pulsatile blood flow from the heart.  Thus, there is more blood traveling at a higher speed through stiff arteries during systole (the phase when blood is pushed out of the heart).
3. Older people tend to develop high SYSTOLIC blood pressure (SBP), also known as systolic hypertension.  The SBP is the top number of your blood pressure reading.
4. Your maximum heart rate (HR) drops progressively with age.  This is one of the immutable laws of aging and you can’t change this by becoming more healthy.  You can estimate your max HR using this formula: 220-age.
5. With regular aerobic activity, you can improve the efficiency at which your heart is able to deliver oxygen-rich blood to your muscles during exercise. This will improve your ability to exercise.
6. Your VO₂max measures the maximum amount of oxygen that your body can use during exercise.  VO2max declines with age but you can slow this process with regular aerobic exercise.
7. In healthy people, the ability of the heart to pump blood is preserved.  However, the ability of the left ventricle (LV) to fill with blood drops by up to 50% between 20 and 80 years of age.  This occurs in part because the muscular wall of the LV becomes thicker and stiffer.
8. Some of the heart’s natural pacemaker cells are replaced by scar tissue, making the older heart more prone to abnormal heart rhythms such as atrial fibrillation.

The Brain

1.  Many brain diseases that occur in the elderly, including Alzheimer’s dementia and Parkinson’s disease, are due to the accumulation of misfolded proteins inside and around the brain cells.  Older individuals without brain disease also tend to have elevated levels of these abnormal proteins in the brain.
2. The brain gets smaller with age.  Most brain cells die off in two areas of the brain:  the prefrontal cortex (responsible for planning and decision making) and the hippocampus (involved in the formation of new memories and learning).  These structural changes explain many of the declines in cognition mentioned below.
3. Most people experience an age-related decline in mental functions such as sustained and selective attention, processing speed and  episodic memory (or recollection of previous experiences). Older people are more easily distracted and less able to multitask.
4. An older person’s response time is approximately 1.5 times slower than that of a young person.
5. Mental tasks associated with crystallized intelligence including vocabulary, reading, school-based knowledge and verbal reasoning skills are preserved with age.  
6. Often, a normal older adult will complain of a “memory problem” that is actually a problem with poor attention and/or slower speed of processing information.
7. Many studies have shown that moderate or strenuous physical exercise decreases risk of cognitive decline.  For example, short-term aerobic training (4-6 months) increased overall brain volume and reversed some of the age-related volume loss in the prefrontal cortex and hippocampus.  Exercise promotes formation of new blood vessels, brain cells and synapses in the brain. During exercise, the body releases a protein called brain-derived neurotrophic growth factor (BDNF) which enhances brain function.
8. Sleep efficiency decreases with age.  Older people spend less time in deep sleep and they have more nighttime awakenings which means that their sleep is more fragmented and less restful.
9. Older people have changes in their sleep/wake cycle meaning that they are less likely to have long periods of restful sleep at night and long periods of wakefulness during the day. 

Mouth, Esophagus and Stomach 

1. Aging causes the gums to thin and recede, which exposes teeth and increases the risk of developing cavities.
2. Many older people are not able to efficiently transfer a bite of food from the mouth into the esophagus, increasing the risk for aspiration of food.
3. Heartburn symptoms may become more severe because more acidic stomach juice flows backward into the esophagus in older people.
4. Liquid food takes longer to transit through the stomach into the small intestine after eating.  This can cause early satiety or nausea.
5. The wall of the stomach is more likely to become inflamed and the stomach lining becomes more sensitive to irritants such as NSAID pain medications (ibuprofen or naproxen).  In older people, these medications can erode the stomach lining and cause ulcers.
6. Over 50% of seniors are infected with the stomach bacteria called Helicobacter pylori.  This chronic infection is often asymptomatic but sometimes can cause ulcers in the stomach lining.
7. Basal metabolic rate declines with age.  With every decade, your body requires 10% fewer calories per day.  By age 80, you would need approximately 50% of the calories that you needed at age 20.  In part, this is due to loss of muscle mass with age.

The Pancreas and Liver

1. Specialized cells in the pancreas make insulin, a hormone which allows the cells of your body to use the glucose that you eat as fuel.  An increasing number of these pancreatic cells die off as we get older. As a result, blood glucose levels after eating are higher in older people compared to young people.  Advancing age also increases your risk for developing insulin resistance and diabetes.
2. The liver is responsible for processing drugs and removing harmful chemicals from the bloodstream.  The liver shrinks by 20-40% with age while blood flow to the liver drops by up to 50% between age 20 and age 90. 
3. The decreased blood flow means that the liver is less able to clear drugs from the body.  Metabolic clearance of drugs is 20-40% slower in older individuals and they often require a lower dose of a medication compared with younger patients.
4. With age there is an accumulation of fat cells and waste products in the liver tissue. This fat accumulation often leads to fatty liver disease, the most common liver disease worldwide.

The Gut

1. Older people are less able to absorb calcium and zinc from food.  Vitamin B12 deficiency becomes more common.
2. You are more likely to develop lactose intolerance as you get older, especially if you are not Caucasian.  One study estimates that 65% of the global population is lactose intolerant, although the rate varies by region, from less than 10% in Northern Europe to as high as 95% in parts of Asia and Africa.  Symptoms may include abdominal pain, bloating, diarrhea, gas and nausea after consuming milk-based food.
3. Food moves more slowly through the colon and chronic constipation is common.  This is more likely to be a result of medication side effects and immobility than to aging itself.
4. The slower transit of food through the colon means that more water is absorbed back into the bloodstream.  This produces harder stool which also contributes to constipation.
5. On colonoscopy, many seniors are found to have diverticula, or small outpouchings of the inner lining of the colon.  Sometimes these diverticula can become infected or cause bleeding although they are usually asymptomatic.
6. Normally, the mucosal wall of the large intestine acts as a barrier to prevent undesirable molecules from entering the bloodstream.  With age, this barrier becomes less effective. Thus, older individuals typically have increased levels of pro inflammatory molecules such as bacteria, toxins and antigens moving into the bloodstream from the gut. The intestinal mucosal barrier dysfunction described here is implicated in several conditions including diabetes, metabolic syndrome, fatty liver disease and irritable bowel syndrome.

Reference

Fillit, H., Rockwood, K., & Young, J. B. (2016). Brocklehurst’s Textbook of Geriatric Medicine and Gerontology. Berlin: Elsevier.