Journals of Gerontology Series B: Psychological Sciences and Social Sciences, Vol 54, Issue 3 P173-P179, Copyright © 1999 by The Gerontological Society of America
Origins of individual differences in episodic memory in the oldest-old: a population-based study of identical and same-sex fraternal twins aged 80 and older
B Johansson, K Whitfield, NL Pedersen, SM Hofer, F Ahern and GE McClearn
Institute of Gerontology, University College of Health Sciences, Jonkoping, Sweden. [email protected]
The relative importance of genetic and environmental influences on episodic
memory in very late life was studied using a quantitative genetic approach.
Identical (n = 125) and same-sex fraternal (n = 157) twin pairs, aged 80
and older (mean age = 83.3; SD = 3.1) and without a diagnosis of dementia
were tested with seven memory measures: (1-2) Digit Span Forward and
Backwards, (3) Prose Recall, (4) Thurstone's picture memory test, and the
Memory in Reality (MIR) test, including the subtasks of (5) free recall,
(6) recognition, and (7) relocation. Heritabilities, estimated by
structural equation modeling, ranged from .04 to .49. The digit span
backward test showed the highest heritability (h2 = .49), while
heritabilities were typically lower for the long-term memory measures. The
results demonstrate genetic influences on memory in the oldest-old, but
suggest that the magnitude of these effects differs across memory measures.
