Dementia is a syndrome that affects approximately 4.4 million individuals in North America. Dementia affects memory, and normal cognitive functioning such as controlling emotions and behaviors and problem solving. There are several types of dementia and cognitive ability is affected in varying degrees. To diagnose dementia more than one brain function must be deteriorating along with memory. There is a strong tie between dementia and Alzheimer’s disease, especially with individuals aged 65 or over. Dementia associated with improper nutrition, removable tumors or drug/alcohol abuse can usually be treated, while dementia caused by Alzheimer’s disease or similar diseases and disorders is largely untreatable. The most common causes of dementia affect the neurons of the brain. In Alzheimer’s disease protein clumps of beta-amyloid form plaques, and fibrous tangles of tau protein which affect normal brain function.
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Types of Dementia
A variety of different cortical disorders impact cortical dementia. Diseases such as Alzheimer's disease, Creutzfeldt-Jakob disease, frontotemporal dementia or Pick’s disease affect the cerebral cortex.(2) The affected area of the brain in cortical dementia is responsible for many cognitive processes. When an individual suffers from cortical dementia, most often language skills and memory will be affected; changes in their motivation are also likely to be seen. (2) In each of these diseases nerve cells or specific areas of the brain are destroyed. Lewy body disease and stroke can also play a factor in cortical dementia.(3)
In subcortical dementia areas of the brain that are deeper than the cortex are affected. Diseases that affect subcortical areas of the brain influence subcortical dementia, Parkinson's disease, and Huntington's disease are some examples; AIDS can also cause this type of dementia. (3) When an individual has subcortical dementia their memory and language is usually not as severely affected as in cortical dementia, but they usually experience motor abnormalities, they may find it difficult to pay attention and concentrate. (4)
It is possible for cortical and subcortical dementia to be present in one individual.
Several different diseases can cause dementia or it can appear naturally in an aged brain, but all forms of dementia are progressive. Each type of disease and all forms of dementia cause structures and nerves in the brain to be damaged, and as time progresses there are more structures and nerves that get destroyed. (5)
Common causes of dementia and areas of the brain affected
Alzheimer’s disease is the most common cause of cortical dementias, 50-80% of dementia cases are caused because of Alzheimer’s disease. (5) While most individuals with Alzheimer’s disease are aged over 65 it is possible to have Alzheimer’s disease in a persons late 40s. (5) Alzheimer’s disease affects a persons behavior and mood, their ability to learn new information and solve problems, they may also have problems communicating. (6) In Alzheimer’s disease there are abnormal growths present in the brain, these abnormalities cause severe damage to the brain and destroy neurons and connections within the brain, these growths are called amyloid plaques and neurofibrillary tangles. (6)
Vascular dementia is a result of improper blood flow to the brain, when there is no blood supply to the brain for even a short amount of time, ie. a stroke, there are areas and structures in the brain that may be destroyed or severely damaged. (5) Symptoms may be similar to other diseases that cause dementia but these symptoms appear suddenly after an individual has had a stroke or has suffered from a head injury. Individuals with vascular dementia may experience severe confusion, problems with concentration and attention, depression, memory problems and problems with speaking. These individuals may also have difficulty walking and may also become restless, along with visual and auditory hallucinations and delusions. (5)
Frontotemporal dementia affects the frontal and temporal lobes of the brain. These areas of the brain are responsible for some types of movement, speech, planning and emotions.(7) In this type of dementia the cells are damaged and the cells and tissue in those areas of the brain shrink. When these areas deteriorate an individual will have reduced functioning ability to perform these tasks. (7) Frontotemporal dementia usually affects the younger age bracket of those with dementia, so there are more instances of individuals in their late 40s and 50s with this type of dementia. (7) Frontotemporal dementia can be divided into three categories, which progress and destroy different cognitive abilities. Behavioral variant FTD (bvFTD) usually causes changes in a persons emotions, they may loose the ability to feel empathy, in this type of frontotemporal dementia a person will loose the ability to control or change their emotions. (8) Primary progressive aphasia (PPA) affects a persons ability to speak and communicate. In early stages a persons speaking and writing skills may deteriorate and in later stages they may have difficulty with any forms of communication and they may not even understand when another individual is trying to communicate with them. (9) The two forms of PPA are semantic dementia and progressive nonfluent aphasia; these different forms affect a persons ability to express any meaning in their words, and their ability to form and pronounce words respectively. (7) The last category is FTD movement disorders, which affect muscle functions. The involuntary, automatic muscles are affected in these disorders; sometimes language and behavior are also affected. (7) Corticobasal degeneration (CBD), and Progressive supranuclear palsy (PSP) are the two main disorders. CBD causes spasms and shakiness along with lack of coordination, while PSP causes issues for movements such as walking and balance. (7)
Dementia with Lewy bodies
Dementia with Lewy bodies (DLB) is a common form of dementia and it has characterized by the loss of cognitive functioning, in this type of dementia there is also periodical changes in alertness, visual delusions that re-occur, and loss of sudden movements as in Parkinsons disease. (10) This form of dementia is caused by Lewy bodies, which are clumps of alpha-synuclein protein, that build up in the nuclei of neurons. (10) The cause for this build up is unknown but these clumps of alpha-synuclein protein have been linked to other disorders also such as Parkinsons. (10)
Huntingtons Disease and Parkinsons
Huntingtons Disease and Parkinsons are movement disorders, both disease are characterized by deteriorating areas of the brain responsible for voluntary and involuntary movement. (6) Huntingtons disease is a neurological disorder where body movements are jerky and very uncoordinated, a persons behavior may also be affected; this disease is genetically inherited. (11) Parkinsons disease affects the central nervous system, a persons movement and motor skills are greatly affected as well as their speaking abilities.
Peripheral inflammatory markers predictive of dementia
Peripheral inflammatory markers are biomarkers that can be used to aid in predicting whether or not an individual is likely to develop dementia.(13) Peripheral inflammatory markers have also helped to aid in understanding the pathways of this disease and the mechanisms associated with it.
Effects of omega-3 fatty acids
There are several factors that influence the risk of getting dementia, including diet. There is evidence that the some essential fatty acids may aid in lowering an individuals risk for Alzheimer’s disease. The ratio of omega-6 to omega-3 fatty acids plays a major role in affecting brain composition, which reduces the risk of getting Alzheimer’s disease. (12)
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3. What is Cortical Dementia? Retrieved March 24th, 2013, from http://www.livestrong.com/
4. Chapter 16: Dementia. Retrieved March 21th, 2013, from http://www.dartmouth.edu
5. What Is Alzheimer's? Retrieved March 25th, 2013, from http://www.alzheimers.org.uk
6. Alzheimers Fact Sheet. Retrieved March 25th, 2013, fromhttp://www.nia.nih.gov/
7. What is vascular dementia? Retrieved March 20th, 2013, http://www.alz.org
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9. Cognitive Neurology and Alzheimer's Disease Center. Retrieved March 25th, 2013, http://brain.northwestern.edu
10. NINDS Dementia With Lewy Bodies Information Page. Retrieved March 24th, 2013, http://www.ninds.nih.gov/
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12. Loef M, Walach H.(2007) The omega-6/omega-3 ratio and dementia or cognitive decline: a systematic review on human studies and biological evidence. J Nutr Gerontol Geriatr. 32(1):1-23. doi: 10.1080/21551197.2012.752335.
13. Metti AL, Cauley JA. (2012) How predictive of dementia are peripheral inflammatory markers in the elderly? Neurodegener Dis Manag. 1;2(6):609-622.