Alzheimer’s is an irreversible degenerative brain disorder that tends to alter human capabilities of behavior, memory and thinking. It usually occurs in older people – over 60 years and, knowing to be usually causing dementia. The disease is often over-looked as one of the common signs of aging, but it shouldn’t be done as it worsens with time. Though the exact cause remains mysterious, it includes a combination of genetic, environmental, and lifestyle factors.
Alzheimer’s was first discovered by Dr. Alois Alzheimer in 1906 when he noticed unusual activity in the brain tissue of a woman who died of unusual causes.
Scientists continue to unravel the complex changes that take place in the brain during the onset and progression of the disease. The damage appears to take place a decade or more before cognitive and memory problems become evident in the hippocampus, part of brain’s limbic system which involved in emotions, learning and the formation of memories.
Abnormal deposition of proteins forms amyloid plaques and neurofibrillary or tau tangles throughout the brain are the main hallmarks of the disease. There is also loss of connection between neurons, inhibiting transmission of messages to and from the brain Ultimately, the neurons die and as the disease progresses, the brain tissue has shrunk significantly.
More than 5 million people in America suffer from Alzheimer’s and the numbers are mounting as the population ages. According to a recent study, it is the third largest cause of death in the U.S. in older people. The average life expectancy for people suffering from Alzheimer’s is 3-4 years if the person is over 80 years and between 10-15 years in younger people keeping in mind other medical conditions.
Early onset or Familial Alzheimer’s appears in people aged between 30-60 years of age and accounts for under 5% of all Alzheimer’s cases. It is usually inherited and caused by any one of a number of different single-gene mutations, such as mutations on chromosome 21, which causes the atypical form of amyloid precursor protein (APP) to be formed.
As stated earlier, in the preclinical stage, the patient may appear completely normal on physical and mental examination. There are usually three stages of the disease:
- Early stage or Mild Alzheimer’s
- Middle/ Moderate Stage
- Advanced/ Severe/ Late Stage
In the onset of the disease, a person may be able carry out normal activities independently like drive, work and other day-to-day activities while experiencing mild memory lapses like:
- Forgetting important dates, events and names,
- Struggle to find the right word in a conversation,
- Misplacing personal belongings and inability to retrace steps,
- Getting lost on a familiar route,
- Repetitive questions and conversations,
- Poor decision-making ability,
- Challenges in problem solving, trouble paying bills and solving simple calculations,
- Inability to plan and organize events, and
- Mood and personality changes.
Moderate Stage: This stage is usually the longest and patients may require greater care. Symptoms include:
- Increased difficulty and time in performing everyday tasks,
- Worsened ability to absorb and remember information like forgetting where the bathroom is, unable to recognize family members,
- Disorientation – confusion regarding place, time, people and things,
- Inability to carry out simple or sequential tasks like cooking a meal, playing a game, choosing and wearing clothes, operate simple equipment, etc..
- Impaired speech, writing and spelling errors, reading,
- Impaired visuospatial skills: Inability to judge distance or seeing three-dimensional objects making it difficult to climb stairs etc.
- Lack of logical thinking and organizing thoughts, decreased attention span,
- Personality changes including suspiciousness, delusions, hallucinations, wandering away from home and getting lost, irritability, restlessness, depressed, fearful and socially withdrawn.
- Obsessive, compulsive and socially unacceptable behavior like using vulgar language, undressing at inappropriate times.
In the later stages, the person is completely dependent on others, cannot communicate, does not recognize anyone and sense of self. Has
- Difficulty in swallowing, seizures,
- Disturbed sleep patterns,
- Increased risk of infections, and
- Loss of bladder control.
Although there is at present no cure for Alzheimer’s, current approaches aim at maintaining mental function, managing behavioral problems and slowing or delaying the symptoms of the disease.
The mainstay of symptomatic therapy for patients with Alzheimer’s is the use of two main drug types: Cholinesterase inhibitors and a partial NMDA (N-methyl D-aspartate) antagonist. The drugs approved by the F.D.A modulate neurotransmitters either acetylcholine or glutamate.
Cholinesterase inhibitors are usually well tolerated and prescribed to treat dementia in patients with Alzheimer’s disease, as well as other cognitive symptoms such as memory loss, problems with thinking, confusion and other thought processes. These drugs act by slowing down or preventing the breakdown of acetylcholine, a neurotransmitter, keeping communication between nerve cells going. Thus, delaying worsening of symptoms for 6-12 months, on an average.
Memantine is prescribed for treatment of moderate to severe Alzheimer’s. This medicine has been shown to decrease abnormal activity and improve the ability to think and remember. It can be used alone or with Donepezil and works by regulating the activity of glutamate.
Calcium enters the cell when glutamate attaches itself to “docking sites” on the surface of the cell, called NMDA. Learning and memory is facilitated by this process, aided by cell signaling. In Alzheimer’s disease, however, damaged cells release excess glutamate, which speeds up cell damage as they are overexposed to calcium, leading to the development of a chronic condition. Partial blockage by Memantine, of NMDA receptors prevents the series of events that can cause possible destruction.
To treat the secondary behavioral symptoms of Alzheimer’s, the following classes of psychotropic medications have been used. However, these drugs have limited or no efficacy.
- Antidepressants
- Anxiolytics
- Antiparkinsonian agents
- Beta-blockers
- Antiepileptic drugs (for their effects on behavior)
- Neuroleptics
In ongoing clinical trials, scientists are developing and practically implementing various interventions that could bear fruit such as immunization therapy, drug therapies, cognitive training and physical activity.
A variety of experimental therapies have been proposed for AD. To being with, antiamyloid therapy, estrogen therapy, free-radical scavenger therapy and vitamin E therapy are some of them. The results have been disappointing though when these therapies were brought under study.
ScienceSwitch 