Types of Age-Related Dementia


Clinical dementia results from pathologies affecting the central nervous system. Patients have deficiencies in cognitive functions such as the thinking process, memory, planning, and judgment. Dementia is most common in individuals above the age of sixty-five. Common types include Alzheimer's dementia, which is the most prevalent type, vascular dementia, Lewy Body dementia, Frontotemporal dementia, and Wernicke-Korsakoff syndrome dementia. The types have different pathological mechanisms.

Vascular dementia results when there is impaired blood circulation to part of the brain: this reduced blood flow is called ischemia. The cause for the impaired circulation may be thrombosis on the major blood vessels or hemorrhage. Hypertension is a risk factor for vascular dementia.

Alzheimer's dementia is a common neurodegenerative condition among the elderly and the most common form of dementia. It results when proteins in the form of neurofibrillary tangles accumulate in the brain, resulting in the death of neurons. Alzheimer's kills over 120,000 Americans evey year, and at any time 5 million are thought to be living with this disease. Lewy body dementia can be divided into lewy body dementia proper and Parkinson's dementia. The difference between the two is the timing of when obvious cognitive decline occurs. Both cause movement disorders in the early stages. If the patient suffers a decline in cognitive function within a year, the dementia is called Lewy Body dementia. Past a year and it's called Parkinson's dementia. Frontotemporal dementia is a neurodegenerative disease affecting the frontal and temporal lobes of the brain. As opposed to other types of dementia, frontotemporal dementia has a nontrivial incidence in younger individuals below the age of sixty-five. Finally, Wernicke Korsakoff syndrome results from a deficiency of vitamin B1; this deficiency may be induced by chronic alcoholism.

Creutzfeldt-Jakob dementia. This uncommon disease cannot be predicted as no risk factors have been identified. This condition may be because of stores of irresistible proteins called prions. Creutzfeldt-Jakob can be acquired. Scientists aren’t sure how but protein structures called prions appear to be part of the cause. These prions can be introduced to the body during, say, a cornea transplant. Signs of this lethal condition usually show up after age 60.

Mixed dementia. Post-mortem and autopsy investigations of the cerebrums of individuals 80 years old and older who had dementia show that many had signs of multiple types. A combination of Alzheimer's, Lewy body dementia, and vascular dementia may show up in an individual. Scientists are trying to figure how having blended dementia influences symptoms and what implications it has for choice of treatment.

Huntington's Disease. This hereditary condition causes specific nerve cells in your cerebrum and spinal cord to deteriorate. Signs typically show up around age 30 or 40.

Traumatic brain injury (TBI). Head injuries afflict boxed, football players, or servicemen as an occupational hazard, and many cases of TBI are from traffic accidents. This condition can cause dementia and parkinsonism. Symptoms may not show up until years after the injury.

The most prevalent type of dementia in the United States is Alzheimer's, making up 70 percent of diagnosed dementia cases. About 7 million Americans have age-related dementia. Experts estimate that one in every six women and one in every ten men past the age of fifty-five years are likely to develop dementia at some point in their lives. The two types of LBD are dementia with Lewy bodies and Parkinson's disease dementia. The difference between the two (for a differential diagnosis) is when the cognitive symptoms start showing up and when movement disorders begin. In its early stages Parkinson's disease dementia makes the patient unable to control his or her movement. Walking is slower and the person may show muscle tremors. Later there are signs of dementia. Dementia with Lewy bodies seems like Alzheimer’s at first with memory loss and personality changes. In the more advanced stages it can cause hallucinations and give the patient involuntary movement or failure to be able to move.

Experts estimate Dementia with Lewy Bodies makes up 1 in 20 dementia cases.

Deloitte’s 2020 Global Healthcare Outlook says “Dementia currently impacts over 50 million people aged 60 and above globally. The number is expected to reach 82 million by 2030 and 152 million by 2050.”

Diagnosis

Doctors use signs, symptoms, and biomarkers to diagnose dementia. Dementia usually produces cognitive decline, and patients will present with memory loss, impaired judgment and thinking, and agnosia, which is an inability to recognize objects previously known to the patient (Duong, Patel & Chang, 2017). An individual may also have apraxia; he or she is not able to perform tasks that were previously routine, such as bathing or even cooking. It is also not uncommon for patients to manifest behavioral and psychological signs in the forms of psychosis, apathy, delusions, and even hallucinations.

Diagnostic tests for dementia include routine laboratory tests to rule out other diseases, brain imaging, and testing for biomarkers. A complete blood count and a comprehensive metabolic panel can give doctors some insight into patient health. A volumetric MRI imaging study on key brain lobes, can look for shrinkage - a sign of dementia. A standard CT scan or MRI is particularly useful in identifying vascular dementia. Functional imaging tests such as SPECT and PET scans can often identify brain pathologies. (Kumar & Tsao, 2019).

In Alzheimer's dementia, cerebrospinal fluid (CSF) biomarkers can be used for diagnosis. The specific biomarkers are the 42-amino acid A isoform (AB42) and the phosphorylated tau proteins (Zverová, 2018). The biomarkers of Parkinson's disease include oxidative stress-related biomarkers such as Protein DJ-1 and co-enzyme Q10. Alpha synuclein and the neurofibrillary light chai proteins that may abnormally accumulate in the brain are also diagnostic biomarkers of various degenerative types of dementia. Research on the use of diagnostic biomarkers in multiple forms of dementia is, however, still ongoing.

Most individuals living with dementia are past the age of sixty-five and have many associated comorbidities. Epidemiologists estimate that on average, such individuals have four chronic diseases besides dementia; common comorbidities include diabetes, hypertension, musculoskeletal disorders, and chronic cardiac conditions such as heart failure.

Diabetes due to uncontrolled blood sugar levels puts patients at an increased risk of microvascular and macrovascular complications. Hypertension, on the other hand, results due to uncontrolled blood pressure exposes older individuals to the risk of hemorrhagic cerebrovascular accidents from the rupture of the blood vessels.

Dementia Glossary

Mild Cognitive Impairment

How do doctors know if someone has dementia? How do they distinguish different tyoes of dementia?

Dementia has no easy biomarkers. Doctors can’t analyze blood and find a hallmark of dementia. It is diagnosed by observation of patient behavior. Post-death autopsies can help identify the cause of the dementia - e.g. lewy bodies in the brain for Lewy Body dementia and plaques for Alzheimer’s.

Is dementia reversible? Can it be cured?

In most cases, no. There are cases of vascular dementia for which improvements in blood flow have partially reversed the dementia, but Alzheimers and Lewy Body Dementia, the most common types, cannot be cured or reversed. Drug therapy may be able to retard the progression of the dementia symptoms, but they do not generally recede.

I heard people with brain cancer can get dementia.

That's right.

Do people with dementia sometimes come out of it for a short period?

Some demenetia patients spontaneously appear to lose their dementia, at least for a short time, in something called paradroxial lucidity. Paradoxical Lucidity, or Terminal Lucidity, is a phenomenon that has been described in medical literature for almost a century but is yet to be explained. Understanding the mechanism behind Paradoxical Lucidity could radically change treatment of dementia and other neurological phenomena.

Tramsmission for Person to Person?

Infectious diseases occur when pathogens get inside the body. Animal to human disease is infectious but not contagious. Contagious diseases are infectious diseases that spread from person to person. Infectiousness refers to how many bacteria, pathogens, etc are needed to infect.

The prevailing wisdom is that disease of old age (heart disease, cancer, diabetes, dementia) are not caused by infections and are not a contagion risk to anyone. However, some scientists suspect that these diseases may in fact be caused - or partially caused - by unknown viruses or other agents.

Prions, which were discovered in the 1980s, have been implicated in diseases of the nervous system, even if the mechanism is not understood. There is informed speculation - unproven yet - that prions may cause Alzheimer’s. And further, that prions pass from person to person and that Alzheimer’s is therefore transmissible. Casual contact is still thought to not cause prion transmission, but medical procedures in which a metal instrument enters the body of someone with Alzheimer’s prions (even if the disease has not manifested itself) could be a transfer channel if the instruments are later used on another patient. Prions are known to stick to stainless steel and conventional sterilization methods may be inadequate to prevent prion transfer. This is still speculative, but it is intriguing.

Prevention

There's no guaranteed method to prevent or forestall dementia; however, there are steps one can take that may help.

Keep your psyche active. Intellectually invigorating exercises, for example, working out riddles and playing word games may postpone the beginning of dementia. Learning a new skill or a new language, although difficult, can have benefits.

Be socially and physically active.

Stop smoking. Manage cardiovascular risk factors.

Get good nutrition. Maintain a healthy diet. It is thought that including green leafy vegetables such as kale and spinach protect against cognitive decline.

Some research suggests that individuals with low blood serum levels of vitamin D have a higher risk of Alzheimer's and other types of dementia.

Some experts believe sufficient sleep helps reduce the chance of a person contracting Alzheimer's disease.

Lewy Body (Spenish)
Alzheimer's (Spanish)
Dementia (Spanish)

References

Duong, S., Patel, T., & Chang, F. (2017). Dementia: What pharmacists need to know. Canadian pharmacists journal : CPJ = Revue des pharmaciens du Canada : RPC, 150(2), 118–129. doi:10.1177/1715163517690745. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384525/

HealthyPeople, (2019). Dementias, Including Alzheimer’s Disease. Retrieved from: https://www.healthypeople.gov/2020/topics-objectives/topic/dementias-including-alzheimers-disease

Hills, K. (2019). Dementia Statistics- U.S. & Worldwide Stats. Retrieved from: https://braintest.com/dementia-stats-u-s-worldwide/

Kumar, A., & Tsao, J.W. (2019). Alzheimer Disease. Treasure Island: StatPearls Publishing. Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK499922/

Zverová M. (2018). Alzheimer's disease and blood-based biomarkers - potential contexts of use. Neuropsychiatric disease and treatment, 14, 1877–1882. doi:10.2147/NDT.S172285. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6055879/