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ARTICLES: Pieter Jelle Visser, Arnold Kester, Jellemer Jolles, and Frans Verhey Ten-year risk of dementia in subjects with mild cognitive impairment Neurology 2006; 67: 1201-1207 [Abstract] [Full text] [PDF]

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Ten-year risk of dementia in subjects with mild cognitive impairment

Francesco Panza, Cristiano Capurso, Alessia D’Introno, Anna M. Colacicco, Antonio Capurso, and Vincenzo Solfrizzi   (13 November 2006)

Reply from the Authors

Pieter Jelle Visser, Arnold Kester, Jellemer Jolles, and Frans Verhey   (13 November 2006)

Ten-year risk of dementia in subjects with mild cognitive impairment 13 November 2006
Francesco Panza, Department of Geriatrics, Center for Aging Brain, Memory Unit, University of Bari Policlinico, Piazza Giulio Cesare, 11, 70124 Bari - Italy, Cristiano Capurso, Alessia D’Introno, Anna M. Colacicco, Antonio Capurso, and Vincenzo Solfrizzi Send Correspondence to journal: Re: Ten-year risk of dementia in subjects with mild cognitive impairment geriat.dot{at}geriatria.uniba.it Francesco Panza, et al.	We read with great interest the study by Visser et al. The authors show that the majority of their patients (40-85 years old) with mild cognitive impairment (MCI) did not progress to dementia in a 10-year follow-up. In addition, the dementia risk in subjects with MCI was strongly dependent on age and varied with the definition of MCI used. [1] The authors discuss these results in relation to studies that included subjects with MCI across a smaller age range and with a shorter follow-up. [2,3] In the Italian Longitudinal Study on Aging (ILSA) [2], we evaluated 2,963 individuals from a population-based sample and found a progression rate to dementia of 3.8/100 person-years in a 3.5-year follow- up. We used a more general concept of MCI, selecting these MCI patients on the basis of the memory loss. Therefore, they may be well represented by amnestic MCI (aMCI), and in the study by Visser et al this was the only predementia syndrome subgroup that developed dementia in the long term. [1] Compared to population-based studies with a 10-year follow-up that used the definition of aMCI and were conducted in subjects of on average 75 to 77 years, [3] the 10-year dementia risk in the group of subjects with aMCI of 70 to 85 years old from the study by Visser et al was 0.55 to 0.72 higher. [1] This finding suggests that the dementia risk of subjects with MCI is substantially higher in a memory clinic setting than in population-based settings, confirming the heterogeneity in progression to dementia of MCI and other predementia syndromes of population-based studies with shorter follow-up. [2-4] Previous data suggested that, in contrast with clinical-based studies where progression is more uniform, in population-based studies the MCI classification is unstable. The apparent homogeneity of MCI and its progression to dementia in clinical-based samples may reflect referral patterns and selection criteria suggesting that MCI is a heterogeneous descriptor and that the outcome at follow-up depends on which population is studied and how MCI is defined. [3,4] Furthermore, the study by Visser et al demonstrates that the risk for dementia in the long term was dependent on the definition of MCI. The highest risk for dementia was observed when the criteria of aMCI and mild functional impairment (a score of 3 on the Global Deterioration Scale) were used. [1] In particular, several recent studies have suggested that subjects classified as having MCI could have visual, auditory, or muscoloskeletal disabilities impairing their activities of daily living (ADL), in the absence of functionally disabling cognitive impairment. [3,5] In the early stages of cognitive impairment, subtle but important changes in everyday functional competence are evident. In the ILSA, while we generally adhered to the diagnostic criteria for MCI as defined by Petersen et al, [2,3] we allowed for the presence of noncognitive disabilities and comorbid illnesses. In conclusion, we suggest that a predementia syndrome with higher predictive diagnostic value may have a cognitive pattern with a central role for memory decline (aMCI) and with the category of normal "ADL/instrumental ADL" criterion suggesting that the diagnosis of MCI should include subtle functional changes in everyday life activities (mild functional impairment). References 1. Visser PJ, Kester A, Jolles J, Verhey F. Ten-year risk of dementia in subjects with mild cognitive impairment. Neurology 2006;67:1201–1207. 2. Solfrizzi V, Panza F, Colacicco AM, et al for the Italian Longitudinal Study on Aging Working Group. Vascular risk factors, incidence of MCI, and rates of progression to dementia. Neurology. 2004;63:1882-1891. 3. Panza F, D'Introno A, Colacicco AM, et al.Current epidemiology of mild cognitive impairment and other predementia syndromes. Am J Geriatr Psychiatry 2005;13:633-644. 4. Panza F, Capurso C, D'Introno A, Colacicco AM, Capurso A, Solfrizzi V. Heterogeneity of mild cognitive impairment and other predementia syndromes in progression to dementia. Neurobiol Aging 2006 Sep 6; [Epub ahead of print]. 5. Boeve B, McCormick J, Smith G, et al. Mild cognitive impairment in the oldest old. Neurology 2003;60:477-480. Disclosures: The authors report no conflicts of interest.
Reply from the Authors 13 November 2006
Pieter Jelle Visser, Department of Psychiatry and Neuropsychology, University of Maastricht PO Box 616, 6200 MD Maastricht, The Netherlands, Arnold Kester, Jellemer Jolles, and Frans Verhey Send Correspondence to journal: Re: Reply from the Authors pj.visser{at}np.unimaas.nl Pieter Jelle Visser, et al.	We thank Dr Panza et al for their comments. They suggest that the predictive accuracy of MCI for dementia can be improved if MCI is defined as amnestic MCI in combination with subtle functional changes in activities of daily living. There is evidence that functional impairments may improve the predictive accuracy of MCI for dementia.[6,7] In our sample, the 10-year risk of dementia in subjects with both amnestic MCI and mild functional impairment was somewhat higher than that in subjects with other types of MCI (10-year risk was 0.56 in the total sample, 0 in the age group 40-54 years, 0.58 in the age group 55-69 years, and 1.0 in the age group 70-85 years). [1] However, a disadvantage of a combination of amnestic MCI with functional changes may be a decrease in sensitivity to detect subjects with preclinical dementia as some subjects with preclinical dementia do not have functional deficits and some may have non-amnestic MCI. [7,8,9] The sensitivity of the combination of amestic MCI and mild functional impairment for predicting dementia in our sample was 0.55, which was lower than the sensitivity of any other MCI definition in our study (0.64 to 0.93). [1] We would like to emphasize that also a combination of amnestic MCI with mild functional impairment may give a lower risk of dementia in population-based samples than in clinical samples.[1,7-9] References 6. Tabert MH, Albert SM, Borukhova-Milov L, et al. Functional deficits in patients with mild cognitive impairment: prediction of AD. Neurology 2002; 58:758-764. 7. Peres K, Chrysostome V, Fabrigoule C, Orgogozo JM, Dartigues JF, Barberger-Gateau P. Restriction in complex activities of daily living in MCI: impact on outcome. Neurology 2006;67:461-466. 8. Storandt M, Grant EA, Miller JP, Morris JC. Longitudinal course and neuropathologic outcomes in original vs revised MCI and in pre-MCI. Neurology 2006;67:467-473. 9. Palmer K, Backman L, Winblad B, Fratiglioni L. Detection of Alzheimer's disease and dementia in the preclinical phase: population based cohort study. BMJ 2003;326:245. Disclosure: The authors report no conflicts of interest.