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In a large twin registry study from Sweden,
Gatz et al compared heritability for AD in male and female
monozygotic twins, male and female dizygotic twins, and unlike-sex
twins. Concordance rates for monozygotic twins ranged from 45%
to 61%, significantly higher than dizygotic twins which were
19% to 41%. After adjusting for age, there were no significant
differences in heritability between the genders. The authors
suggested that while heritability accounted for 58% to 79% of
the variance, the remainder was likely due to environmental
influences that may be the target of therapeutic interventions
to reduce risk.
Role of genes and environments for
explaining Alzheimer disease
(ARCH GEN PSYcHIATRY 2006;63:168-174)
MARGARET GATZ, PhD,
CHANDRA A. REYNOLDS, PhD,
LAURA FRATIGLIONI, MD, PhD,
BOO JOHANSSON, PhD,
ET AL,
los angeles, ca,
tampa , fl,
stockholm, göteborg, sweden
THE link BETWEEN DEPRESSON
AND DEMENTIA
Two recent studies shed light on the complicated
relationship between depression and dementia in the elderly.
In a 12-year, prospective, epidemiological study, Ganguli et
al studied 1,265 elderly people without dementia at baseline.
Those with depressive symptoms at baseline performed worse on
cognitive measures than those without. However, subsequent cognitive
decline over time was noted only in individuals who developed
dementia. These authors concluded therefore, that depression
is associated cross-sectionally with cognitive impairment but
that subsequent cognitive decline is probably due to incipient
dementia rather than depression. In an autopsy study (Rapp et
al), patients with AD and a lifetime history of depression
were compared to patients without depression. Patients with
depression had higher plaque and tangle counts in the hippocampus
and appeared to experience a more rapid cognitive decline.
Depressive symptoms and cognitive
decline in late life
(ARCH GEN PSYCHiaTRY 2006;63:153-160)
MARY GANGULI, MD, MPH,
YANGCHUN DU, MS,
HIROKO H. DODGE, PhD,
GRAHAM G. RATCLIFF, phd,
ET AL,
PITTSBURGH, PA
Increased hippocampal plaques and
tangles in patients with Alzheimer disease with a lifetime history
of major depression
(ARCH GEN PSYCHIATRY 2006;63:161-167
MICHAEL A. RAPP, MD, PhD,
MICHAL SCHnaIDER-BEERI, PhD,
HILLEL T. GROSSMAN, MD,
MARY SANO, PhD,
ET AL,
NEW YORK, BRONX, NY
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