- University of Kuopio
Series of Reports
Department of Neurology
No. 39
- KUOPION YLIOPISTO
JYVÄSKYLÄN
YLIOPISTOUNIVERSITY OF KUOPIO
UNIVERSITY OF JYVÄSKYLÄ
Tuomo Hänninen
AGE-ASSOCIATED MEMORY
IMPAIRMENT
A neuropsychological and epidemiological study
Doctoral Dissertation
To be presented with the assent of the Faculty of Social Sciences of the University of Jyväskylä for public examination in the auditorium S212, Seminarium building, University of Jyväskylä, on November 23, 1996, at 12 o'clock noon.
Departments of Neurology and Medicine
University of Kuopio
Department of Psychology
University of Jyväskylä
Kuopio 1996
Author's address:
Department of Neurology
Distribution: University of Kuopio
P.O. Box 1627
70211 Kuopio
FINLAND
Tel: +358 17 173004
Fax: +358 17 173019
Supervisors:
Professor Hilkka Soininen, M.D.
Department of Neurology
University of Kuopio
Professor Heikki Lyytinen, Ph.D.
Department of Psychology
University of Jyväskylä
Reviewers:
Professor Raimo Sulkava, M.D.
Department of Geriatrics
University of Kuopio
Hely Kalska, Ph.D.
Department of Psychology
University of Helsinki
Opponent:
Docent Juhani Vilkki, Ph.D.
Department of Psychology
University of Helsinki
ISBN 951-780-971-9
ISSN 0357-6043
Kuopio University Printing Office
Kuopio 1996
Finland
Hänninen, Tuomo. Age-associated memory impairment. A neuropsychological
and epidemiological study.
Series of Reports, No 39, Department of Neurology, University of Kuopio.
1996. 86 p. + appendix.
ISBN 951-780-971-9
ISSN 0357-6043
URL of the department of Neuroscience and Neurology: http://www.uku.fi/laitokset/neuro/
URL of the thesis: http://www.uku.fi/laitokset/neuro/39the.htm
ABSTRACT
The aim of this study was to characterize the neuropsychological and epidemiological aspects involved in diagnosing age-related changes in cognition. The properties of the diagnostic criteria for age-associated memory impairment (AAMI) proposed by the National Institute of Mental Health and for age-associated cognitive decline (AACD) proposed by the International Psychogeriatric Association were evaluated in a large random sample and in smaller select groups of elderly subjects.
According to the high prevalence of AAMI found in the present study, AAMI appeared likely to be a phenomenon of normal aging rather than a continuum from normal aging to a pathologic state such as Alzheimer's disease. As in some previous studies, the neuropsychological methods used for AAMI diagnosis also appeared ambiguous in this study. The follow-up of AAMI subjects suggested that AAMI, in general, is nonprogressive, but that the AAMI population also includes subjects with very early dementia. However, these subjects can be differentiated by means of a more detailed neuropsychological evaluation. In comparison with age-matched controls, AAMI subjects appeared to be impaired not only in tests assessing memory, but also in tests of executive functions associated with frontal lobe function. This finding agrees with previous reports suggesting an important role for frontal lobe dysfunction in the memory loss of elderly people. The comparison of subjects with high and low frequencies of subjective complaints of memory loss suggested that these subjective feelings of memory impairment are more closely associated with personality traits than with actual memory performance in normal elderly people. This complicates the use of memory complaints in the inclusion criteria for AAMI and AACD diagnosis.
The prevalence of AACD was found to be lower than that of AAMI. As AAMI tends to identify a very heterogeneous subject group, the AACD diagnosis might prove superior to AAMI for differentiating a meaningful subgroup from the elderly population, both for research purposes and in clinical settings. This remains to be confirmed in follow-up studies. This study demonstrated that the AAMI diagnosis appears to identify a very heterogeneous group of subjects of only vague clinical or theoretical significance. The significance of the AACD diagnosis remains to be confirmed in follow-up studies. Nevertheless, more reliable diagnostic approaches are needed in studies trying to identify risk factors for dementia or to find treatments for very early dementia.
National Library of Medicine Classification: WT 100, WL 103.5, WL 359
Medical Subject Headings: aging; memory; memory disorders; dementia; Alzheimer’s disease; neuropsychological tests; risk factors; epidemiology; diagnosis; classification; personality; frontal lobe/physiopathology.
ACKNOWLEDGEMENTS
This study was conducted in the Departments of Neurology and Medicine, University of Kuopio and Kuopio University Hospital, during the years 1989-1994.
I am greatly indebted to Professor Paavo Riekkinen, Sr., MD, for providing excellent facilities for carrying out this work. I wish to express my gratitude to Professor Hilkka Soininen, MD, and Professor Heikki Lyytinen, PhD, the supervisors of this thesis, for their patient guidance in various domains of research and scientific writing. I also wish to thank the official referees of this thesis, Professor Raimo Sulkava, MD, and Hely Kalska, PhD, for their valuable suggestions for improving the manuscript.
I have enjoyed working together with my highly competent collaborators, Keijo Koivisto, MD, Docent Kari Reinikainen, MD, Docent Eeva-Liisa Helkala, PhD, Merja Hallikainen, MD, Matti Vanhanen, MA, and Mikko Laakso, MD, from the Department of Neurology; Professor Kalevi Pyörälä, MD, Professor Markku Laakso, MD, and Leena Mykkänen, MD, from the Department of Medicine; and Kaarina Partanen, MD, from the Department of Radiology of the University of Kuopio. I sincerely thank you all for your indispensable contributions.
I will always remember with pleasure and gratitude the entire personnel of the Memory Research Clinic of the Department of Neurology for creating a friendly and supportive atmosphere in which to work during the years of this study.
I sincerely thank the personnel of the entire Department of Neurology of Kuopio University Hospital, the Library and the Printing Office of the University of Kuopio for valuable collaboration during this study. I also am thankful to Leslie Schultz-Suhonen, MD, for revising the English language of the manuscript.
I also wish to thank the participants in the different phases of the study.
My deep gratitude is due to my mother and my late father for giving me the opportunity and encouragement for academic education. I warmly thank my sister, her husband and my other relatives as well as all my friends for support during the years of this study.
Finally, I owe my deepest gratitude to my dear wife, Erja, for encouragement and support. I dedicate this thesis to her and to our infant twins born just prior to the public defense of this thesis.
The present study was financially supported by the University of Kuopio, the Medical Research Council of the Academy of Finland and the North Savo Regional Fund of the Finnish Cultural Foundation.
Kuopio, November 1996
Tuomo Hänninen
LIST OF ORIGINAL PUBLICATIONS
This thesis is based on the following original publications that are referred to in the text by the Roman numerals I-V:
(The publications are not included in the internet version of this thesis due to copyright reasons. Reprints of the publications may be inquired both from the author and from http://www.uku.fi/laitokset/neuro/publicat.htm)
I Koivisto K, Reinikainen KJ, Hänninen T, Vanhanen M, Helkala E-L, Mykkänen L, Laakso M, Pyörälä K, Riekkinen PJ Sr. Prevalence of age-associated memory impairment in a randomly selected population from eastern Finland. Neurology 45:741-747, 1995.
II Hänninen T, Hallikainen M, Koivisto K, Partanen K, Laakso MP, Riekkinen PJ Sr, Soininen H. Decline of frontal lobe functions in subjects with age-associated memory impairment. Neurology 48:148-153, 1997.
III Hänninen T, Reinikainen KJ, Helkala E-L, Koivisto K, Mykkänen L, Laakso M, Pyörälä K, Riekkinen PJ. Subjective memory complaints and personality traits in normal elderly subjects. Journal of the American Geriatrics Society 42:1-4, 1994.
IV Hänninen T, Hallikainen M, Koivisto K, Helkala E-L, Reinikainen KJ, Soininen H, Mykkänen L, Laakso M, Pyörälä K, Riekkinen PJ Sr. A follow-up study of age-associated memory impairment: Neuropsychological predictors of dementia. Journal of the American Geriatrics Society 43:1007-1015, 1995.
V Hänninen T, Koivisto K, Reinikainen KJ, Helkala E-L, Soininen H, Mykkänen L, Laakso M, Riekkinen PJ Sr. Prevalence of ageing-associated cognitive decline in an elderly population. Age and Ageing 25:201-205, 1996.