Skip to main content

Delirium in elderly patients: association with educational attainment

  • Sónia Martins (a1), José Artur Paiva (a2), Mário R. Simões (a3) and Lia Fernandes (a4)

Among cognitive reserve markers, educational attainment is the most widely studied, with several studies establishing a strong association with risk of dementia. However, it has not yet been fully examined in delirium. This study aims to analyse the relationship between educational attainment and delirium.


The study included elderly hospitalised patients admitted (≥48 h) into an intermediate care unit (IMCU) of Intensive Care Medicine Service. Exclusion criteria were as follows: Glasgow Coma Scale (total≤11), blindness/deafness, inability to communicate or to speak Portuguese. The European Portuguese Version of the Confusion Assessment Method (CAM) was used for delirium assessment.


The final sample (n=157) had a mean age of 78.8 (SD=7.6) the majority being female (52.2%), married (51.5%) and with low educational level (49%). According to CAM, 21% of the patients had delirium. The delirium group presented the fewest years of education (median 1 vs. 4), with statistical significance (p=0.003). Delirium was more frequent among male patients [odds ratio (OR) 0.32; 95% confidence interval (CI) 0.12–0.86; p=0.023], as well as those patients with lower education (OR 0.76; 95% CI 0.62–0.95; p=0.016), and with respiratory disease (OR 3.35; 95% CI 1.20–9.33; p=0.020), after controlling for age and medication.


Similar to previous studies, these findings point to a negative correlation between education and delirium. This study appears as an attempt to contribute to the knowledge about the role of cognitive reserve in risk of delirium, particularly because is the first one that has been carried out in an IMCU, with lower educated elderly patients. Further studies are needed to clarify this relationship considering other markers (e.g. cognitive activities), which can contribute to the definition of preventive strategies.

Corresponding author
Lia Fernandes, Faculty of Medicine, University of Porto, Al. Hernâni Monteiro, 4200-319 Porto, Portugal. Tel: +00 351 22 205 2525; Fax: +00 351 22 551 3623; E-mail:
Hide All
1. Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet 2014;383:911922.
2. Siddiqi N, House AO, Holmes JD. Occurrence and outcome of delirium in medical in-patients: a systematic literature review. Age Ageing 2006;35:350364.
3. Witlox J, Eurelings LS, De Jonghe JF, Kalisvaart KJ, Eikelenboom P, Van Gool WA. Delirium in elderly patients and the risk of postdischarge mortality, institutionalization, and dementia: a meta-analysis. JAMA 2010;304:443451.
4. Leentjens AF, Rundell J, Rummans T et al. Delirium: an evidence-based medicine (EBM) monograph for psychosomatic medicine practice, commissioned by the Academy of Psychosomatic Medicine (APM) and the European Association of Consultation Liaison Psychiatry and Psychosomatics (EACLPP). J Psychosom Res 2012;73:149152.
5. Inouye SK, Charpentier PA. Precipitating factors for delirium in hospitalized elderly persons. Predictive model and interrelationship with baseline vulnerability. JAMA 1996;275:852857.
6. Jones RN, Yang FM, Zhang Y, Kiely DK, Marcantonio ER, Inouye SK. Does educational attainment contribute to risk for delirium? A potential role for cognitive reserve. J Gerontol A Biol Sci Med Sci 2006;61:13071311.
7. Jones RN, Manly J, Glymour MM, Rentz DM, Jefferson AL, Stern Y. Conceptual and measurement challenges in research on cognitive reserve. J Int Neuropsychol Soc 2011;17:593601.
8. Katzman R, Terry R, Deteresa R et al. Clinical, pathological, and neurochemical changes in dementia: a subgroup with preserved mental status and numerous neocortical plaques. Ann Neurol 1988;23:138144.
9. Stern Y. What is cognitive reserve? Theory and research application of the reserve concept. J Int Neuropsychol Soc 2002;8:448460.
10. Stern Y. The concept of cognitive reserve: a catalyst for research. J Clin Exp Neuropsychol 2003;25:589593.
11. Stern Y. Cognitive reserve in ageing and Alzheimer’s disease. Lancet Neurol 2012;11:10061012.
12. Fratiglioni L, Wang HX. Brain reserve hypothesis in dementia. J Alzheimer’s Dis 2007;12:1122.
13. Dekhtyar S, Wang HX, Scott K, Goodman A, Koupil I, Herlitz A. A life-course study of cognitive reserve in dementia-from childhood to old age. Am J Geriatr Psychiatry 2015;23:885896.
14. Saczynski JS, Inouye SK, Kosar C et al. Brain reserve capacity on symptom onset after brain injury: a formulation and review of evidence for threshold theory. Neuropsychology 1993;7:273295.
15. Fay TB, Yeates KO, Taylor HG et al. Cognitive reserve as a moderator of postconcussive symptoms in children with complicated and uncomplicated mild traumatic brain injury. J Int Neuropsychol Soc 2010;16:94105.
16. Bigler ED, Stern Y. Traumatic brain injury and reserve. Handb Clin Neurol 2015;128:691710.
17. Staff RT, Murray AD, Deary IJ, Whalley LJ. What provides cerebral reserve? Brain 2004;127:11911199.
18. Stern Y. Cognitive reserve. Neuropsychologia 2009;47:20152028.
19. Valenzuela MJ, Sachdev P. Brain reserve and cognitive decline: a non-parametric systematic review. Psychol Med 2006;36:10651073.
20. Valenzuela MJ, Sachdev P. Brain reserve and dementia: a systematic review. Psychol Med 2006;36:441454.
21. Valenzuela MJ, Sachdev P. Assessment of complex mental activity across the lifespan: development of the Lifetime of Experiences Questionnaire (LEQ). Psychol Med 2007;37:10151026.
22. Schmand B, Smit JH, Geerlings MI, Lindeboom J. The effects of intelligence and education on the development of dementia. A test of the brain reserve hypothesis. Psychol Med 1997;27:13371344.
23. Nelson HE. National Adult Reading Test (NART): for the assessment of premorbid intelligence in patients with dementia: test manual. Windsor, UK: NFER-Nelson, 1982.
24. Mortimer JA, Graves AB. Education and other socioeconomic determinants of dementia and Alzheimer’s disease. Neurology 1993;43(Suppl. 4):S39S40.
25. Meng X, D’Arcy C. Education and dementia in the context of the cognitive reserve hypothesis: a systematic review with meta-analyses and qualitative analyses. PLoS One 2012;7:e38268.
26. Hugo J, Ganguli M. Dementia and cognitive impairment: epidemiology, diagnosis, and treatment. Clin Geriatr Med 2014;30:421442.
27. Pompei P, Foreman M, Rudberg MA, Inouye SK, Braund V, Cassel CK. Delirium in hospitalized older persons: outcomes and predictors. J Am Geriatr Soc 1994;42:809815.
28. Galanakis P, Bickel H, Gradinger R, Von Gumppenberg S, Förstl H. Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications. Int J Geriatr Psychiatry 2001;16:349355.
29. Yang FM, Inouye SK, Fearing MA, Kiely DK, Marcantonio ER, Jones RN. Participation in activity and risk for incident delirium. J Am Geriatr Soc 2008;56:14791484.
30. Fisher BW, Flowerdew G. A simple model for predicting postoperative delirium in older patients undergoing elective orthopedic surgery. J Am Geriatr Soc 1995;43:175178.
31. Lerner AJ, Hedera P, Koss E, Stuckey J, Friedland RP. Delirium in Alzheimer disease. Alzheimer Dis Assoc Disord 1997;11:1620.
32. Mccusker J, Cole M, Dendukuri N, Belzile É, Primeau F. Delirium in older medical inpatients and subsequent cognitive and functional status: a prospective study. CMAJ 2001;165:575583.
33. Leung JM, Sands LP, Mullen EA, Wang Y, Vaurio L. Are preoperative depressive symptoms associated with postoperative delirium in geriatric surgical patients? J Gerontol A Biol Sci Med Sci 2005;60:15631568.
34. Saczynski JS, Inouye SK, Kosar CM. Cognitive and brain reserve and the risk of postoperative delirium in older patients: analysis of data from a prospective observational study. Lancet Psychiatry 2014;1:437443.
35. Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet 1974;2:8184.
36. Inouye SK, Van Dyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz RI. Clarifying confusion: the Confusion Assessment Method. A new method for detection of delirium. Ann Intern Med 1990;113:941948.
37. Martins S, Lourenço C, Pinto-De-Sousa J et al. Validation study of the European Portuguese version of the Confusion Assessment Method (CAM). Int Psychogeriatr 2015;27:777784.
38. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. DSM-IV-TR, 4th edn. (Text Review). Washington, DC: APA, 2000.
39. Folstein MF, Folstein SE, Mchugh PR. Mini-mental state. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975;12:189198.
40. Wechsler D. Wechsler Adult Intelligence Scale-III. San Antonio, TX: The Psychological Corporation, 1997.
41. Saxena S, Lawley D. Delirium in the elderly: a clinical review. Postgrad Med J 2009;85:405413.
42. National Institute for Health and Clinical Excellence. Delirium: diagnosis, prevention and management (Clinical guideline 103) NICE. 2010. Available at Accessed June 2015.
43. Elie M, Cole MG, Primeau FJ, Bellavance F. Delirium risk factors in elderly hospitalized patients. J Gen Intern Med 1998;13:204212.
44. Noimark D. Predicting the onset of delirium in the post-operative patient. Age Ageing 2009;38:368373.
45. Aldemir M, Özen S, Kara IH, Sir A, Baç B. Predisposing factors for delirium in the surgical intensive care unit. Crit Care 2001;5:265.
46. Takeuchi T, Matsushima E, Moriya H, Shintani M, Nakamura S. Delirium in inpatients with respiratory diseases. Psychiatry Clin Neurosci 2005;59:253258.
47. Cavallazzi R, Saad M, Marik PE. Delirium in the ICU: an overview. Ann Intensive Care 2012;2:49.
48. Manly JJ, Byrd D, Touradji P, Sanchez D, Stern Y. Literacy and cognitive change among ethnically diverse elders. Int J Psychol 2004;39:4760.
49. Katzman R. Education and the prevalence of dementia and Alzheimer’s disease. Neurology 1993;43:1320.
50. Jones RN, Fong TG, Metzger E et al. Aging, brain disease, and reserve: implications for delirium. Am J Geriatr Psychiatry 2010;18:117127.
51. Kolanowski AM, Fick DM, Clare L, Therrien B, Gill DJ. An intervention for delirium superimposed on dementia based on cognitive reserve theory. Aging Ment Health 2010;14:232242.
52. Kolanowski AM, Fick DM, Litaker MS, Clare L, Leslie D, Boustani M. Study protocol for the recreational stimulation for elders as a vehicle to resolve delirium superimposed on dementia (Reserve For DSD) trial. Trials 2011;12:119.
53. Kramer AF, Bherer L, Colcombe SJ, Dong W, Greenough WT. Environmental influences on cognitive and brain plasticity during aging. J Gerontol A Biol Sci Med Sci 2004;59:M940M957.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Acta Neuropsychiatrica
  • ISSN: 0924-2708
  • EISSN: 1601-5215
  • URL: /core/journals/acta-neuropsychiatrica
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 8
Total number of PDF views: 123 *
Loading metrics...

Abstract views

Total abstract views: 437 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 23rd February 2018. This data will be updated every 24 hours.