Journal of General Internal Medicine

, Volume 21, Issue 12, pp 1276–1281 | Cite as

Recoverable cognitive dysfunction at hospital admission in older persons during acute illness

  • Sharon K. InouyeEmail author
  • Ying Zhang
  • Ling Han
  • Linda Leo-Summers
  • Richard Jones
  • Edward Marcantonio
Original Articles


BACKGROUND: While acute illness and hospitalization represent pivotal events for older persons, their contribution to recoverable cognitive dysfunction (RCD) has not been well examined.

OBJECTIVE: Our goals were to estimate the frequency and degree of RCD in an older hospitalized cohort; to examine the relationship of RCD with delirium and dementia; and to determine 1-year cognitive outcomes.

DESIGN: Prospective cohort study.

PARTICIPANTS: Four hundred and sixty patients aged ≥70 years drawn from consecutive admissions to an academic hospital.

MEASUREMENTS: Patients underwent interviews daily during hospitalization and at 1 year. The primary outcome was RCD, defined as an admission Mini-Mental State Examination (MMSE) score that improved by 3 or more points by discharge.

RESULTS: Recoverable cognitive dysfunction occurred in 179 of 460 (39%) patients, with MMSE impairment at baseline ranging from 3 to 13 points (median=5.0 points). The majority of cases were not characteristic of either delirium or dementia, as 144 of 179 (80%) cases did not meet criteria for delirium, and 133 of 164 (81%) cases did not meet criteria for dementia at baseline. In multivariable analysis controlling for baseline MMSE level, 3 factors were predictive of RCD: higher educational level, preadmission functional impairment, and higher illness severity. At 1 year, further improvement in MMSE score occurred in 38 of 92 (41%) patients with RCD. Recoverable cognitive dysfunction was independently predictive of 1-year mortality with an adjusted odds ratio of 1.82 (95% confidence interval [95% CI] 1.03 to 3.20).

CONCLUSIONS: Acute illness is accompanied by a high rate of RCD that is neither characteristic of delirium or dementia. Our observations underscore the reversible nature of this cognitive dysfunction with continued improvement over the ensuing year, and highlight the potential clinical implications of this under-recognized phenomenon.

Key words

delirium dementia cognitive impairment hospitalization geriatrics 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Covinsky KE, Palmer RM, Fortinsky RH, et al. Loss of independence in activities of daily living in older adults hospitalized with medical illnesses: increased vulnerability with age. J Am Geriatr Soc. 2003;51:451–8.PubMedCrossRefGoogle Scholar
  2. 2.
    Creditor MC. Hazards of hospitalization of the elderly. Ann Intern Med. 1993;118:219–23.PubMedGoogle Scholar
  3. 3.
    Brennan TA, Leape LL, Laird NM, et al. Incidence of adverse events and negligence in hospitalized patients: results of the Harvard Medical Practice Study 1. N Engl J Med. 1991;324:370–6.PubMedCrossRefGoogle Scholar
  4. 4.
    Inouye SK. Current concepts: delirium in older persons. N Engl J Med. 2006;354:1157–65.PubMedCrossRefGoogle Scholar
  5. 5.
    Cole MG. Delirium in elderly patients. Am J Geriatr Psychiatry. 2004;12:7–21.PubMedCrossRefGoogle Scholar
  6. 6.
    Meagher DJ. Delirium: optimising management. BMJ. 2001;322:144–9.PubMedCrossRefGoogle Scholar
  7. 7.
    Fields SD, MacKenzie CR, Charlson ME, Sax FL. Cognitive impairment: can it predict the course of hospitalized patients? J Am Geriatr Soc. 1986;34:579–85.PubMedGoogle Scholar
  8. 8.
    Hickey A, Clinch D, Groarke EP. Prevalence of cognitive impairment in the hospitalized elderly. Int J Geriatr Psychiatry. 1997;12:27–33.PubMedCrossRefGoogle Scholar
  9. 9.
    Fields SD, MacKenzie CR, Charlson ME, Perry SW. Reversibility of cognitive impairment in medical inpatients. Arch Intern Med. 1986;146:1593–6.PubMedCrossRefGoogle Scholar
  10. 10.
    Treloar AJ, Macdonald AJD. Outcome of delirium, Part I: outcome of delirium diagnosed by DSM-III-R, ICD-10 and CAMDEX and derivation of the reversible cognitive dysfunction scale among acute geriatric inpatients. Int J Geriatr Psychiatry. 1997;12:609–13.PubMedCrossRefGoogle Scholar
  11. 11.
    Treloar AJ, Macdonald AJF. Outcome of delirium, Part II: clinical features of reversible cognitive dysfunction. Are they the same as accepted definitions of delirium? Int J Geriatr Psychiatry. 1997;12:614–8.PubMedCrossRefGoogle Scholar
  12. 12.
    Cassel EJ, Leon AC, Kaufman SG. Preliminary evidence of impaired thinking in sick patients. Ann Intern Med. 2001;134:1120–3.Google Scholar
  13. 13.
    Inouye SK, Bogardus ST, Charpentier PA, et al. A multicomponent intervention to prevent delirium in hospitalized older patients. N Engl J Med. 1999;340:669–76.PubMedCrossRefGoogle Scholar
  14. 14.
    Folstein MF, Folstein SE, McHugh PR. The Folstein Mini-Mental State Examination: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189–98.PubMedCrossRefGoogle Scholar
  15. 15.
    Cummings JL. Clinical Neuropsychiatry. Orlando: Grune and Stratton; 1985:9.Google Scholar
  16. 16.
    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;113:941–8.PubMedGoogle Scholar
  17. 17.
    Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged: the index of ADL, a standardized measure of biological and psychosocial function. JAMA. 1963;185:914–9.PubMedGoogle Scholar
  18. 18.
    Cornoni-Huntley J, Brock DB, Ostfeld AM, Taylor JO, Wallace RB. Established Populations for Epidemiologic Studies of the Elderly: Resource Data Book. NIH publication no. 86-2443. Bethesda: National Institute on Aging; 1986.Google Scholar
  19. 19.
    MacPhee GJ, Crowther JA, McAlpine CH. A simple screening test for hearing impairment in elderly patients. Age Ageing. 1988;17:347–51.PubMedCrossRefGoogle Scholar
  20. 20.
    Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Crit Care Med. 1985;13:818–29.PubMedCrossRefGoogle Scholar
  21. 21.
    Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40:373–83.PubMedCrossRefGoogle Scholar
  22. 22.
    Blessed G, Tomlinson BE, Roth M. The association between quantitative measures of dementia and of senile change in the cerebral grey matter of elderly subjects. Br J Psychiatry. 1968;114:797–811.PubMedGoogle Scholar
  23. 23.
    Uhlmann RF, Larson EB, Buchner DM. Correlations of Mini-Mental State and Modified Dementia Rating Scale to measures of transitional health status in dementia. J Gerontol. 1987;42:33–6.PubMedGoogle Scholar
  24. 24.
    Roccaforte WH, Burke WJ, Bayer BL, Wengel SP. Validation of a telephone version of the Mini-Mental State Examination. J Am Geriatr Soc. 1992;40:697–702.PubMedGoogle Scholar
  25. 25.
    Anthony JC, LeResche L, Niaz U, Von Korff MR, Folstein MF. Limits of the ‘Mini-Mental State’ as a screening test for dementia and delirium among hospital patients. Psychol Med. 1982;12:397–408.PubMedCrossRefGoogle Scholar
  26. 26.
    Tombaugh TN, McIntyre NJ. The Mini-Mental State Examination: a comprehensive review. J Am Geriatr Soc. 1992;40:922–35.PubMedGoogle Scholar
  27. 27.
    Van Belle G, Uhlmann RF, Hughes JP, Larson EB. Reliability of estimates of changes in mental status test performance in senile dementia of the Alzheimer type. J Clin Epidemiol. 1990;43:589–95.PubMedCrossRefGoogle Scholar
  28. 28.
    Salmon DP, Thal LJ, Butters N, Heindel WC. Longitudinal evaluation of dementia of the Alzheimer type: a comparison of 3 standardized mental status examinations. Neurology. 1990;40:1225–30.PubMedGoogle Scholar
  29. 29.
    Stockton P, Cohen-Mansfield J, Billig N. Mental status change in older surgical patients. Am J Geriatr Psychiatry. 2000;8:40–6.PubMedCrossRefGoogle Scholar
  30. 30.
    Inouye SK, Robison JT, Froehlich TE, Richardson ED. The Time and Change Test: a simple screening test for dementia. J Gerontol A Biol Sci Med Sci. 1998;53A:M281-M286.Google Scholar
  31. 31.
    Froehlich TE, Robison JT, Inouye SK. Screening for dementia in the outpatient setting: the time and change test. J Am Geriatr Soc. 1998;46:1506–11.PubMedGoogle Scholar
  32. 32.
    Le Carret N, Lafont S, Letenneur L, Dartigues JF, Mayo W, Fabrigoule C. The effect of education on cognitive performances and its implication for the constitution of the cognitive reserve. Dev Neuropsychol. 2003;23:317–37.PubMedCrossRefGoogle Scholar
  33. 33.
    Liao YC, Liu RS, Teng EL, et al. Cognitive reserve: a SPECT study of 132 Alzheimer’s disease patients with an education range of 0–19 years. Dement Geriatr Cogn Disord. 2005;20:8–14.PubMedCrossRefGoogle Scholar
  34. 34.
    Inouye SK, Charpentier PA. Precipitating factors for delirium in hospitalized elderly persons: predictive model and inter-relationship with baseline vulnerability. JAMA. 1996;275:852–7.PubMedCrossRefGoogle Scholar
  35. 35.
    Cole M, McCusker J, Dendukuri N, Han L. The prognostic significance of subsyndromal delirium in elderly medical inpatients. J Am Geriatr Soc. 2003;51:754–60.PubMedCrossRefGoogle Scholar
  36. 36.
    Levkoff SE, Liptzin B, Cleary P, et al. Subsyndromal delirium. Am J Geriatr Psychiatry. 1996;4:320–9.Google Scholar
  37. 37.
    Jönsson L, Lindgren P, Wimo A, Jönsson B, Winblad B. Costs of Mini-Mental State Examination-related cognitive impairment. Pharmacoeconomics. 1999;16:409–16.PubMedCrossRefGoogle Scholar
  38. 38.
    McKhann G, Drachman D, Folstein M, Katzman R, Price D, Stadlan EM. Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA work group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease. Neurology. 1984;34:939–44.PubMedGoogle Scholar
  39. 39.
    World Health Organization. The ICD-10 Classification of Mental and Behavioral Disorders: Diagnostic Criteria for Research. Geneva: World Health Organization; 1992:F00-F09.Google Scholar
  40. 40.
    American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. fourth edition. Washington, DC: American Psychiatric Association; 1994:133–55.Google Scholar

Copyright information

© the Society of General Internal Medicine 2006

Authors and Affiliations

  • Sharon K. Inouye
    • 1
    • 2
    Email author
  • Ying Zhang
    • 1
    • 2
  • Ling Han
    • 3
  • Linda Leo-Summers
    • 3
  • Richard Jones
    • 1
    • 2
  • Edward Marcantonio
    • 1
    • 2
  1. 1.Department of MedicineBeth Israel Deaconess Medical Center, Harvard Medical SchoolBoston
  2. 2.Aging Brain Center, Institute for Aging ResearchHebrew Senior LifeBoston
  3. 3.Program on AgingYale University School of MedicineNew HavenUSA

Personalised recommendations