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 older individuals above the age of sixty-five (HealthyPeople, 2019). Besides vascular dementia, other types include Alzheimer's dementia, which is the most prevalent type, Parkinson’s 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. Parkinson's dementia arises due to abnormal accumulation of Lewy bodies resulting in neuronal death. 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.

The most prevalent type of dementia in the United States is Alzheimer's, making up 70 percent of diagnosed dementia cases. About 5 million Americans have age-related dementia (Hills, 2019). 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.

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, 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

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/