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ALZHEIMER disease (AD) is now recognised as a serious public health problem.in a large number of people, AD develops at a rather late age of about 65years. Alzheimer was hitherto considered to be a Western problembecause of longer life span - the us forexample has over four million peoplewith this degenerative brain disorder.But of late, AD is rapidly emerging as aimportant problem for the Indian senior citizens.
The Journal of American MedicalAssociation (JAMA) has justbrought out a special issue onAlzheimer disease, highlighting advancements made thisyear. Among the significantresults is the relationshipbetween strokes and AD byDavid Snowdon and his colleagues from the Universityof Kentucky, Lexington.Snowdon's group was looking for clues to understandageing and they persuadedmembers of a Roman Catholic religious order, theSchool Sisters of Notre Damein Mankato, Minnesota, toparticipate in this study. Thesisters took regular psychological tests and gave regularblood samples. He also madean unusual request: wouldthey be willing to donate their brainsafter death? 678 nuns who were 75 orover signed up and so the study took off(JAMA, Vol 277, No 10).
The investigators V the break-through when Sister Mary died in 1995,at the age of I0I and her brain wasexamined. Researchers saw in her brainsigns of devastation from microscopicplaques and tangles to gaping holeswhere millions of brain cells had diedalthough she was quite normal andactive until her death. SlowlySnowdon's group realised that SisterMary was not unique. Until then theyhad considered these old ladies as amodel of successful ageing as despiteadvanced age most of them could live anear normal life both in respect of intellectual and physical functions. Therewere 19 among the 61 deceased nunswho seemed to have escaped the confusion and memory loss that makes thisform of dementia (irreversible organicdeterioration of mental faculties) so devastating.
According to them the reasonappears to be that these nuns, unliketheir counter parts whose symptomswere severe, had not suffered fromstrokes, especially small strokes so commonplace in the elderly. They noticedthat only 57 per cent of the stroke-freenuns developed dementia as comparedto over 93 per cent of nuns with a historyof mini-strokes. This is considered animportant finding, since it provideswhat may be the clearest sign yet that amedically treatable condition like strokecan accelerate the decline of Alzheimer'spatients and makes the differencebetween independent living and nursedat home. By preventing strokes inolder people, it may now be possible topostpone the development of symptomsof people with AD.
Even if medical researchers canuse this information to be able toreduce the symptoms of people with AD,they would have achieved a greaterdeal. Besides costing a lot to the healthcare systems and patients' families,the social consequences of nursing aparent with AD are significant. Scientistsestimate that postponing the symptoms of AD by five years could cut thehealth care costs by nearly half and thepatient will have five more years of near normal life.
Scientists have been looking forclues to understand what causesAlzheimer's and what we have noware a intriguing set of hypothesis.The most popular theory holds that thedisease process starts when a proteincalled beta amyloid accumulates outsidethe nerve cells, forming the depositsknown as plaques. The plaquesappear to impair the ability of theneurons in the brain to absorbglucose from the blood stream resultingin the devastating mental problems.Another hypothesis says that AD beginsnot with beta amyloid but with aprotein called tau. According to theproponents of this theory, abnormalvariants of this protein clutter theinteriors of the neurons with tangledfilaments that disrupt cellular metabolism.
Researchers have nowrealised through the study ofgenes that contribute to theformation of these lesionsthat both theories may betrue. People with this defective gene involved in makingbeta amyloid have high rates of AD. But there areothers with a AD-susceptibilitygene called Apo-E4, which produces a protein that appears to affect tau. According to AD researchers,people who carry two copiesof this gene have an elevatedrisk of developing AD before70. And if they suffer a stroke,they are more likely to developfull-blown dementia.