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Memory and aging

One of the key concerns of older adults is the experience of memory loss, especially as it is one of the hallmark symptoms of Alzheimer's disease. However, memory loss is qualitatively different in normal aging from the kind of memory loss associated with a diagnosis of Alzheimer's.[1]

Contents

[edit] Mild cognitive impairment

Recent research has identified a transitional state between the cognitive changes of normal aging and Alzheimer's disease (AD), known as mild cognitive impairment (MCI). Many people who experience mild cognitive impairment are at a high risk of developing Alzheimer's disease. Several studies have indicated that MCI individuals are at an increased risk for developing AD, ranging from 1% to 25% per year; 24% of MCI patients progressed to AD in 2 years and 20% more over 3 years, whereas a recent study indicated that the progression of MCI subjects was 55% in 4.5 years.[2]


[edit] Memory decline in normal aging

The ability to encode new memories of events or facts and working memory shows decline in both cross-sectional and longitudinal studies.[3] Studies comparing the effects of aging on episodic memory, semantic memory, short-term memory and priming find that episodic memory is especially impaired in normal aging.[4] These deficits may be related to impairments seen in the ability to refresh recently processed information.[5] In addition, even when equated in memory for a particular item or fact, older adults tend to be worse at remembering the source of their information,[6] a deficit that may be related to declines in the ability to bind information together in memory during encoding and retrieve those associations at a later time.[7][8]

A postmortem examination of five brains of elderly people with better memory than average'called "super aged" -- found that these individuals had less fiber-like tangles of tau protein than found in typical elderly brains, but a similar amount of amyloid plaque.[9]

[edit] Domains of memory mostly spared

In contrast, implicit, or procedural memory typically shows no decline with age[10], short-term memory shows little decline[4] and semantic knowledge, such as vocabulary, actually improves somewhat with age.[11] In addition, the enhancement seen in memory for emotional events is also maintained with age.[12]

[edit] Qualitative changes

Most research on memory and aging has focused on how older adults perform less well at a particular memory task. However, recently researchers have also discovered that simply saying that older adults are doing the same thing, only less of it, is not always accurate. In some cases, older adults seem to be using different strategies than younger adults. For example, brain imaging studies have revealed that older adults are more likely to use both hemispheres when completing memory tasks than younger adults.[13] In addition, older adults sometimes show a positivity effect when remembering information, which seems to be a result of the increased focus on regulating emotion seen with age.[12] For instance, eye tracking reveals that older adults showed preferential looking toward happy faces and away from sad faces.[14]

[edit] See also

[edit] References

  1. ^ Budson AE, Price BH (February 2005). "Memory dysfunction". N. Engl. J. Med. 352 (7): 692'9. doi:10.1056/NEJMra041071. PMID 15716563. http://content.nejm.org/cgi/pmidlookup?view=short&pmid=15716563&promo=ONFLNS19. 
  2. ^ Arn�¡iz E, Almkvist O (2003). "Neuropsychological features of mild cognitive impairment and preclinical Alzheimer's disease". Acta Neurol. Scand., Suppl. 179: 34'41. PMID 12603249. 
  3. ^ Hedden T, Gabrieli JD (February 2004). "Insights into the ageing mind: a view from cognitive neuroscience". Nat. Rev. Neurosci. 5 (2): 87'96. doi:10.1038/nrn132310.1038/nrn1323. PMID 14735112. 
  4. ^ a b Nilsson LG (2003). "Memory function in normal aging". Acta Neurol. Scand., Suppl. 179: 7'13. PMID 12603244. 
  5. ^ Johnson MK, Reeder JA, Raye CL, Mitchell KJ (2002). "Second thoughts versus second looks: An age-related deficit in selectively refreshing just-active information". Psychological Science 13: 64'7. http://memlab1.eng.yale.edu/PDFs/2002_Johnson_Reeder_Raye_PsychSci.pdf. 
  6. ^ Johnson MK, Hashtroudi S, Lindsay DS (July 1993). "Source monitoring". Psychol Bull 114 (1): 3'28. PMID 8346328. http://content.apa.org/journals/bul/114/1/3. 
  7. ^ Naveh-Benjamin M (September 2000). "Adult age differences in memory performance: tests of an associative deficit hypothesis". J Exp Psychol Learn Mem Cogn 26 (5): 1170'87. PMID 11009251. http://content.apa.org/journals/xlm/26/5/1170. 
  8. ^ Mitchell KJ, Johnson MK, Raye CL, Mather M, D'Esposito M (September 2000). "Aging and reflective processes of working memory: binding and test load deficits". Psychol Aging 15 (3): 527'41. PMID 11014715. http://content.apa.org/journals/pag/15/3/527. 
  9. ^ EurekAlert. 'Super-aged' brains reveal first secrets of sharp memory in old age.
  10. ^ Fleischman DA, Wilson RS, Gabrieli JD, Bienias JL, Bennett DA (December 2004). "A longitudinal study of implicit and explicit memory in old persons". Psychol Aging 19 (4): 617'25. doi:10.1037/0882-7974.19.4.617. PMID 15584787. http://content.apa.org/journals/pag/19/4/617. 
  11. ^ Verhaeghen P (June 2003). "Aging and vocabulary scores: a meta-analysis". Psychol Aging 18 (2): 332'9. PMID 12825780. http://content.apa.org/journals/pag/18/2/332. 
  12. ^ a b Mather M, Carstensen LL (October 2005). "Aging and motivated cognition: the positivity effect in attention and memory". Trends Cogn. Sci. (Regul. Ed.) 9 (10): 496'502. doi:10.1016/j.tics.2005.08.005. PMID 16154382. http://linkinghub.elsevier.com/retrieve/pii/S1364-6613(05)00237-8. 
  13. ^ Cabeza R (March 2002). "Hemispheric asymmetry reduction in older adults: the HAROLD model". Psychol Aging 17 (1): 85'100. PMID 11931290. http://content.apa.org/journals/pag/17/1/85. 
  14. ^ Isaacowitz DM, Wadlinger HA, Goren D, Wilson HR (March 2006). "Selective preference in visual fixation away from negative images in old age? An eye-tracking study". Psychol Aging 21 (1): 40'8. doi:10.1037/0882-7974.21.1.40. PMID 16594790. http://content.apa.org/journals/pag/21/1/40. 

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