
An aging-associated disease (commonly termed age-related disease, ARD) is a
disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
that is most often seen with increasing frequency with increasing
senescence
Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with ...
. They are essentially
complications of senescence, distinguished from the
aging
Ageing (or aging in American English) is the process of becoming Old age, older until death. The term refers mainly to humans, many other animals, and fungi; whereas for example, bacteria, perennial plants and some simple animals are potentiall ...
process itself because all adult animals age (
with rare exceptions) but not all adult animals experience all age-associated diseases. The term does not refer to age-specific diseases, such as the
childhood diseases chicken pox and
measles
Measles (probably from Middle Dutch or Middle High German ''masel(e)'', meaning "blemish, blood blister") is a highly contagious, Vaccine-preventable diseases, vaccine-preventable infectious disease caused by Measles morbillivirus, measles v ...
, only diseases of the elderly. They are also not
accelerated aging disease
Progeroid syndromes (PS) are a group of rare genetic disorders that mimic Physiology, physiological senescence, aging, making affected individuals appear to be older than they are. The term ''progeroid syndrome'' does not necessarily imply progeri ...
s, all of which are
genetic disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders ...
s.
Examples of aging-associated diseases are
atherosclerosis
Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...
and
cardiovascular disease
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...
,
cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
,
arthritis,
cataracts
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or double vision, halos around ligh ...
,
osteoporosis
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in Bone fracture, fracture risk.
It is the most common reason f ...
,
type 2 diabetes,
hypertension
Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...
and
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...
. The incidence of all of these diseases increases
exponentially with age.
Of the roughly 150,000 people who die each day across the globe, about two thirds—100,000 per day—die of age-related causes.
In industrialized nations, the proportion is higher, reaching 90%.
Patterns of differences
By age 3, about 30% of
rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...
s have had cancer, whereas by age 85 about 30% of humans have had cancer. Humans,
dogs and
rabbit
Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...
s get Alzheimer's disease, but
rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s do not. Elderly rodents typically die of cancer or
kidney disease
Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an Inflammation, inflammatory kidney disease and has several types according to the location of the inflammation. Infla ...
, but not of cardiovascular disease. In humans, the relative incidence of cancer increases exponentially with age for most cancers, but levels off or may even decline by age 60–75(although
colon/
rectal
The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces te ...
cancer continues to increase).
People with the so-called
segmental progerias are vulnerable to different sets of diseases. Those with
Werner's syndrome experience osteoporosis, cataracts, and, cardiovascular disease, but not
neurodegeneration
A neurodegenerative disease is caused by the progressive loss of neurons, in the process known as neurodegeneration. Neuronal damage may also ultimately result in their cell death, death. Neurodegenerative diseases include amyotrophic lateral sc ...
or Alzheimer's disease; those with
Down syndrome have type 2 diabetes and Alzheimer's disease, but not high
blood pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term ...
, osteoporosis or cataracts. In
Bloom syndrome, those affected most often die of
cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
.
Research
Aging (senescence) increases vulnerability to age-associated diseases, whereas
genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...
determines vulnerability or resistance between species and individuals within species. Some age-related changes (like
graying hair) are said to be unrelated to an increase in
mortality. But some
biogerontologist
Biogerontology is the sub-field of gerontology concerned with the biological aging process, its evolutionary origins, and potential means to intervene in the process. The term "biogerontology" was coined by S. Rattan, and came in regular use wi ...
s believe that the same underlying changes that cause
graying hair also increase mortality in other organ systems and that understanding the incidence of age-associated disease will advance knowledge of the
biology
Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...
of senescence just as knowledge of
childhood diseases advanced knowledge of
human development.
Strategies for engineered negligible senescence (SENS) is an emerging research strategy that aims to repair "root causes" for age-related illness and degeneration, as well as develop medical procedures to periodically repair all such damage in the human body, thereby maintaining a youth-like state indefinitely.
[The SENS Platform: An Engineering Approach to Curing Aging]
". Methuselah Foundation. Retrieved on June 28, 2008. The SENS programme has identified seven types of aging-related damage, and feasible solutions have been outlined for each. Some critics argue that the SENS agenda is optimistic at best, and that the aging process is too complex and little-understood for SENS to be scientific or implementable in the foreseeable future.
It has been proposed that age-related diseases are mediated by vicious cycles.
On the basis of extensive research,
DNA damage has emerged a major culprit in
cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
and numerous other diseases related to
ageing
Ageing (or aging in American English) is the process of becoming older until death. The term refers mainly to humans, many other animals, and fungi; whereas for example, bacteria, perennial plants and some simple animals are potentially biol ...
.
DNA damage can initiate the development of cancer or other aging related diseases depending on several factors. These include the type, amount, and location of the DNA damage in the body, the type of cell experiencing the damage and its stage in the
cell cycle
The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell (biology), cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA (DNA re ...
, and the specific
DNA repair
DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is cons ...
processes available to react to the damage.
[
]
Types
Macular degeneration
Age-related macular degeneration
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no sym ...
(AMD) is a disease that affects the eyes and can lead to vision loss through break down of the central part of the retina called the macula. Degeneration can occur in one eye or both and can be classified as either wet (neovascular) or dry (atrophic). Wet AMD commonly is caused by blood vessels near the retina that lead to swelling of the macula. The cause of dry AMD is less clear, but it is thought to be partly caused by breakdown of light-sensitive cells and tissue surrounding the macula. A major risk factor for AMD is age over the age of 60.
Alzheimer's
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...
is classified as a "protein misfolding" disease. Aging causes mutations in protein folding, and as a result causes deposits of abnormal modified proteins to accumulate in specific areas of the brain. In Alzheimer's, deposits of Beta-amyloid and hyperphosphorylated tau protein form extracellular plaques and extracellular tangles. These deposits are shown to be neurotoxic and cause cognitive impairment due to their initiation of destructive biochemical pathways.
Atherosclerosis
Atherosclerosis
Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...
is categorized as an aging disease and is brought about by vascular remodeling, the accumulation of plaque, and the loss of arterial elasticity. Over time, these processes can stiffen the vasculature. For these reasons, older age is listed as a major risk factor for atherosclerosis. Specifically, the risk of atherosclerosis increases for men above 45 years of age and women above 55 years of age.
Benign prostatic hyperplasia
Benign prostatic hyperplasia (BPH) is a noncancerous enlargement of the prostate gland due to increased growth. An enlarged prostate can result in incomplete or complete blockage of the bladder and interferes with a man's ability to urinate properly. Symptoms include overactive bladder
Overactive bladder (OAB) is a common condition where there is a frequent feeling of needing to urinate to a degree that it negatively affects a person's life. The frequent need to urinate may occur during the day, at night, or both. Loss of bl ...
, decreased stream of urine, hesitancy urinating, and incomplete emptying of the bladder. By age 40, 10% of men will have signs of BPH and by age 60, this percentage increases by 5 fold. Men over the age of 80 have over a 90% chance of developing BPH and almost 80% of men will develop BPH in their lifetime.
Cancer
Although it is possible for cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
to strike at any age, most patients with invasive cancer are over 65, and the most significant risk factor
In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection.
Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...
for developing cancer is age. According to cancer researcher Robert A. Weinberg, "If we lived long enough, sooner or later we all would get cancer." Some of the association between aging and cancer is attributed to immunosenescence, errors accumulated in DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
over a lifetime and age-related changes in the endocrine system
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant Organ (biology), organs. In vertebrat ...
. Aging's effect on cancer is complicated by factors such as DNA damage and inflammation promoting it and factors such as vascular aging and endocrine changes inhibiting it.
Parkinson's
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...
, or simply Parkinson's, is a long-term degenerative disorder of the central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
that mainly affects the motor system
The motor system is the set of central nervous system, central and peripheral nervous system, peripheral structures in the nervous system that support motor functions, i.e. movement. Peripheral structures may include skeletal muscles and Efferen ...
. The disease has many complications, including anxiety, dementia
Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...
, and depression. Parkinson's disease typically occurs in people over the age of 60, of whom about one percent are affected. The prevalence of Parkinson's disease dementia also increases with age, and to a lesser degree, duration of the disease. Exercise in middle age may reduce the risk of PD later in life.
Stroke
Stroke
Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...
was the second most frequent cause of death worldwide in 2011, accounting for 6.2 million deaths (~11% of the total). Stroke could occur at any age, including in childhood, the risk of stroke increases exponentially from 30 years of age, and the cause varies by age. Advanced age is one of the most significant stroke risk factors. 95% of strokes occur in people age 45 and older, and two-thirds of strokes occur in those over the age of 65. A person's risk of dying if he or she does have a stroke also increases with age.
Endocrine diseases
Studies in animal models show that clearance of senescent cells improves multiple age related endocrine disorders.
Osteoporosis
Bone density
Bone density, or bone mineral density, is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although medicine#Clinical practice, clinically it is measured by ...
declines with age. By the age of 85 years, ~70% of women and 30% of men have a osteoporosis
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in Bone fracture, fracture risk.
It is the most common reason f ...
defined as a bone density less than or equal to 2.5 standard deviations lower than young adults.
Metabolic syndrome
The metabolic syndrome is the co-occurrence of metabolic risk factors for type 2 diabetes
Type 2 diabetes (T2D), formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent ...
and cardiovascular disease
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...
( abdominal obesity, hyperglycemia
Hyperglycemia is a condition where unusually high amount of glucose is present in blood. It is defined as blood glucose level exceeding 6.9 mmol/L (125 mg/dL) after fasting for 8 hours or 10 mmol/L (180 mg/dL) 2 hours after eating.
Blood gluc ...
, dyslipidemia
Dyslipidemia is a metabolic disorder characterized by abnormally high or low amounts of any or all lipids (e.g. fats, triglycerides, cholesterol, phospholipids) or lipoproteins in the blood. Dyslipidemia is a risk factor for the development of ...
, and hypertension
Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...
). The prevalence of the metabolic syndrome increases with age reaching close to 50% of people over 60 years old in the USA. as
See also
* Accelerated aging disease
Progeroid syndromes (PS) are a group of rare genetic disorders that mimic Physiology, physiological senescence, aging, making affected individuals appear to be older than they are. The term ''progeroid syndrome'' does not necessarily imply progeri ...
* Alliance for Aging Research
* Gerontology
Gerontology ( ) is the study of the social, culture, cultural, psychology, psychological, cognitive, and biology, biological aspects of aging. The word was coined by Ilya Ilyich Mechnikov in 1903, from the Ancient Greek, Greek ('), meaning "o ...
* Senescence
Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with ...
References
External links
Segmental Progeria
{{Longevity
Geriatrics
Senescence