Alzheimer’s disease and dementia are both commonly seen in elderly individuals. Both diseases impair cognitive functions. Alzheimer’s disease is the commonest cause of dementia. Both diseases affect not only memory but also other cognitive functions. Here, we will discuss all those in detail, highlighting their types, clinical features, signs and symptoms, causes, investigation and diagnosis, prognosis, treatment and care, as well as the difference between Alzheimer’s and dementia.
Alzheimer’s
Alzheimer’s disease has no cure, and it worsens with time progressively impairing cognitive functions. The onset and progression of Alzheimer’s disease is unique to each patient. The actual reason for Alzheimer’s disease is not yet known. Some hypothesize that it is due to the formation of plaques in the brain and neuronal tangles. Early Alzheimer’s presents as loss of memory of recent events. With time, confusion, unstable mood, irritability, aggressive behavior, trouble with speech and understanding, and poor long term memory appear. Social interactions deteriorate with the progression of the disease. Slowly body functions deteriorate leading to death. It is very difficult to predict the life expectancy and disease progression because of the individual differences.
In many people, Alzheimer’s disease runs its course undetected. After the diagnosis people usually live for around seven years. Only a small percentage lives beyond fourteen years after the diagnosis. Tests that assess thinking and behavioral abilities confirm the diagnosis of Alzheimer’s disease. A brain scan gives clues towards excluding other diagnosis like stroke, bleeding inside the brain matter, and space occupying lesions.
Figure 01: Alzheimers Brain
Treatment options available are not curative. They only relieve symptoms. These drugs do not alter the progression of the disease. Various alternate treatment methods are available, but the safety and efficacy data are not available. A caregiver is essential in management of Alzheimer’s disease.
Dementia
Dementia features an impairment of all cognitive functions beyond that due to normal ageing. Dementia is a set of symptoms that may be progressive (most commonly) or static, resulting from degeneration of the cerebral cortex, which controls the “higher” brain functions. It entails a disturbance of memory, thinking, learning ability, language, judgment, orientation, and comprehension. These are accompanied by problems with control of emotions and behavior. Dementia is the commonest among elderly individuals where an estimated 5% of the total population above 65 years of age is involved. Currently available statistics estimate that 1% of the population below 65 years of age, 5-8% of people between 65–74, 20% of people between 75-84 and 30-50% of people 85 years or older are suffering from dementia. Dementia covers a broad spectrum of clinical features.
Although there are no distinct types of dementia, it can be broadly divided into three according to the natural history of the disease. Fixed impairment of cognition is a type of dementia which does not progress in terms of severity. It results from some type of organic brain disease or injury. Vascular dementia is a fixed impairment dementia. (Ex: stroke, meningitis, reduction of oxygenation of cerebral circulation). Slowly progressive dementia is a type of dementia which starts out as an intermittent disturbance of higher brain function and slowly worsens to a stage where there is impairment of activities of daily living. This type of dementia is commonly due to diseases where the nerves degenerate slowly (neurodegenerative). Fronto temporal dementia is a slow progressive dementia due to slow degeneration of the frontal lobe structures. Semantic dementia is a slow progressive dementia which features loss of word meaning and speech meaning. Diffuse Lewy body dementia is similar to Alzheimer’s disease except for the presence of Lewy bodies in the brain. (Ex: Alzheimer’s disease, multiple sclerosis). Rapidly progressive dementia is a type of dementia which does not take years to manifest itself but does so in mere months. (Ex: Creuzfeldt-Jacob’s disease, prion disease).
Treating any primary disorder, treating superimposed delirium, treating even minor medical problems, involving family support, arranging practical help at home, arrange help for carers, drug treatment and arranging institutionalized care in case of failure of home care are the basic principles of care for dementia. Drug treatment is used only when the possible side effects are outweighed by the benefits. In severe behavioral changes such as agitation, emotional instability, occasional use of sedatives is warranted (Promazine, Thioridazine). Antipsychotic drugs may be prescribed in delusions and hallucinations. If depressive features are profound, anti-depressant therapy may be started. Cholinesterase inhibitors acting centrally are of use to approximately half of the patients suffering from dementia due to Alzheimer’s disease. They appear to delay the progression of cognitive impairment and in some cases may even improve symptoms for a time.
What is the difference between Alzheimer’s and Dementia?
• Curability of dementia depends on the cause while Alzheimer’s disease is incurable and progressive.
• Alzheimer’s disease usually starts as short term amnesia while dementia present in various ways.
• The main presenting symptom of Alzheimer’s is memory loss while dementia presents differently according to the type of dementia.
• Alzheimer’s shows loss of function in the temporal lobe in PET scan while dementia show a global loss of function.
Image Courtesy:
1.’Alzheimers brain’ By National Institutes of Health (Public Domain) via Commons Wikimedia
Also read the Difference Between Amnesia and Dementia