Cognitive Patterns of Normal Elderly Subjects Are Consistent With Frontal Cortico-Subcortical and Fronto-Parietal Neuropsychological Models of Brain Aging

Abstract

Three neuropsychological theories have been developed according to a possible existence of a similar pattern of cognitive decline in elderly individuals and patients with brain damage. The respective neuropsychological theories attribute age-related deficits to: (a) dysfunction of the frontal lobes, (b) temporo-parietal dysfunction, or (c) decline of right-hemisphere functions. In the present study, we examined which of these theories best explains the cognitive patterns of normal elderly subjects older than 80 years of age (old elderly). Thirty normal old elderly subjects, 14 patients with subcortical vascular dementia, 14 with mild Alzheimer's disease, 15 with damage of the right hemisphere of the brain, and 20 young elderly controls participated. A test battery covering the main cognitive domains was administered to all participants. A hierarchical cluster analysis revealed five groups of individuals with different cognitive patterns across the whole sample. Old elderly subjects were assigned to four groups according to: (a) preserved overall cognitive performance, (b) processing speed decline, (c) attention decline, or (d) executive impairment. The results of the study are most congruent with models emphasizing frontal-lobe cortical–subcortical and fronto-parietal changes in old age. The results also indicate considerable heterogeneity in the cognitive patterns of normal old elderly adults.

Key words:

• cluster analysis
• frontal aging hypothesis
• hemi-aging hypothesis
• neurodegenerative hypothesis of aging
• neuropsychology
• normal aging

ACKNOWLEDGEMENTS

We thank Professor Tadeusz Parnowski, neuropsychologist Sławomira Kotapka-Minc, MA, and geropsychiatrists from the Second Department of Psychiatry, Institute of Psychiatry and Neurology in Warsaw, Poland, for help in patient recruitment. We thank participants and their families for their generous contribution. We also thank the anonymous reviewers for their helpful comments on the manuscript. This study was supported by funding that Emilia Łojek was awarded by Faculty of Psychology, University of Warsaw (BST 1340/08, 445/01/09, 14502/10, and 161500/51/11).

Notes

OE = old elderly; YE = young elderly; SIVD = subcortical vascular ischemic dementia; AD = Alzheimer's disease; RHD = right-hemisphere damage; MMSE = Mini-Mental State Examination; BDI-II = Beck Depression Inventory-II; ns = not significant.

Note. Only loadings >.4 are shown. CVLT = California Verbal Learning Test-Polish normalization; RHLB-PL = Right-Hemisphere Language Battery-Polish version; WCST = Wisconsin Card-Sorting Test-Polish normalization; WAIS-R (PL) = Polish version of the Wechsler Adult Intelligence Scale-Revised version.

Note. Effect size is expressed as partial eta squared (η²). OE = old elderly; YE = young elderly; SIVD = subcortical vascular ischemic dementia; AD = Alzheimer's disease; RHD = right-hemisphere damage; ns = not significant.

Note. Effect size is expressed as partial eta squared (η²).

OE = old elderly.

F = female; M = male; OE = old elderly; YE = young elderly; SIVD = subcortical vascular ischemic dementia; AD = Alzheimer's disease; SIVD/AD, AD/SIVD = mixed dementia, main disease is first; RHD = right-hemisphere damage; CT = computer tomography; MRI = magnetic resonance imaging; TIA = transient ischemic attack; COPD = chronic obstructive pulmonary disease; EEG = electroencephalogram.