The past three decades saw a dramatic improvement in our understanding of what brings about Alzheimer’s disease. Two proteins are thought to be responsible: amyloid and tau. The most widely accepted theory is that a critical level of amyloid in the brain triggers the build-up of the more toxic tau protein. This has led to several studies testing drugs and vaccines that remove amyloid and tau to see if they can improve or even prevent dementia. Results have been disappointing.
All studies in dementia patients have failed to show improvements, even if amyloid itself was affected. In a prominent case, a vaccine given to patients was shown to have cleared the brain of amyloid of people who nonetheless died of profound dementia.
Over the same period, studies in people destined to develop the condition because of a genetic mutation reported that the changes leading to dementia begin up to 25 years before any symptoms. One logical interpretation is that attempts to find a cure for dementia may have failed because the patients in drug trials were treated too late in the disease process.
Oxford is a subscribing member of The Conversation. Find out how you can write for The Conversation.
Katika miongo mitatu iliyopita kulikuwa na uboreshaji mkubwa katika uelewa wetu wa kile kinachosababisha ugonjwa wa Alzheimer. Inafikiriwa kwamba protini mbili ndizo zinazosababisha ugonjwa huo: amyloid na tau. Nadharia inayokubaliwa sana ni kwamba kiwango kikubwa cha amyloid katika ubongo husababisha kuunganishwa kwa protini ya tau yenye sumu zaidi. Kwa sababu hiyo, utafiti umefanywa ili kuchunguza dawa na chanjo zinazotenganisha amyloid na tau ili kuona kama zinaweza kuboresha au hata kuzuia ugonjwa wa akili. Matokeo yamekuwa yenye kuvunja moyo. Uchunguzi wote uliofanywa kwa wagonjwa wenye ugonjwa wa kukosa fahamu umeshindwa kuonyesha uboreshaji, hata ikiwa amyloid yenyewe iliathiriwa. Katika kesi maarufu, chanjo iliyotolewa kwa wagonjwa ilionyeshwa kuwa imeondoa amyloid kwenye ubongo wa watu ambao walikufa kutokana na ugonjwa wa akili. Katika kipindi hichohicho, utafiti uliofanywa kwa watu waliopaswa kuugua ugonjwa huo kwa sababu ya mabadiliko ya chembe za urithi ulionyesha kwamba mabadiliko yanayoongoza kwenye ugonjwa huo huanza miaka 25 kabla ya dalili zozote kutokea. "Ufafanuzi mmoja wa kimantiki ni kwamba majaribio ya kupata tiba ya ugonjwa wa akili huenda yalishindwa kwa sababu wagonjwa katika majaribio ya dawa walitibiwa marehemu sana katika mchakato wa ugonjwa.""" Oxford ni mwanachama wa usajili wa Mazungumzo. Tafuta jinsi ya kuandika kwa ajili ya The Conversation.