This Article  • References  • Full text PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Social Bookmarking   What's this?

Gary W. Small, MD; Andrew F. Leuchter, MD; Mark A. Mandelkern, MD, PhD; Asenath La Rue, PhD; Anna Okonek, PhD; Robert B. Lufkin, MD; Lissy F. Jarvik, MD, PhD; Steven S. Matsuyama, PhD; William Bondareff, MD, PhD

Arch Neurol. 1993;50(2):209-219.

Abstract
• Objective.
—The study of monozgotic twins can elucidate possible environmental causes for a disease in genetically identical subjects. To this end, we studied a pair of monozygotic female twins appearing discordant for dementia of the Alzheimer type (DAT).

Design.
—Clinical and neuroimaging findings were compared in terms of potential environmental risk factors.

Setting.
—University referral center.

Participants.
—An 81-year-old female monozygotic twin pair.

Outcome Measures.
—Clinical assessments, standardized rating scales, and brain imaging studies, including magnetic resonance imaging, positron emission tomography, and electroencephalography, were performed. Neuropsychological tests were performed initially and after 1 year.

Results.
—Although DAT was confirmed clinically in only one twin, neuropsychological and brain imaging studies suggested that the unaffected twin may be developing the prodrome of DAT. The twins' varied life histories suggest that environmental risk factors may contribute to apparent discordance for DAT and possible delay in disease onset for the currently nondemented twin.

Conclusions.
—These results suggest that both genetic and nongenetic factors influence disease onset and expression. Moreover, review of previous reports of monozygotic twin pairs concordant or discordant for Alzheimer's disease, with adequate family history data, suggest a pattern indicating interactions among age at dementia onset, sex, and familiality. Such patterns point to hypotheses regarding neurobiologically meaningful Alzheimer's disease subgroups.

Author Affiliations
From the Departments of Psychiatry and Biobehavioral Sciences (Drs Small, Leuchter, La Rue, Okonek, Jarvik, and Matsuyama) and Radiological Sciences (Dr Lufkin), UCLA School of Medicine, Los Angeles, Calif; the Veterans Affairs Medical Center, West Los Angeles (Drs Small, Leuchter, Mandelkern, Jarvik, and Matsuyama); the Department of Psychiatry and Behavioral Sciences, University of Southern California, Los Angeles (Dr Bondareff); and the Department of Physics, University of California, Irvine (Dr Mandelkern).

Footnotes
Accepted for publication August 18, 1992.

The views expressed are those of the authors and do not necessarily represent those of the Department of Veterans Affairs.

Reprint requests to the UCLA Neuropsychiatric Institute, 760 Westwood Plaza, Los Angeles, CA 90024 (Dr Small).

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati     What's this?

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Voxel-based analysis of cerebral glucose metabolism in mono- and dizygotic twins discordant for Alzheimer disease
Virta et al.
J. Neurol. Neurosurg. Psychiatry 2009;80:259-266.
ABSTRACT | FULL TEXT  

Role of Genes and Environments for Explaining Alzheimer Disease
Gatz et al.
Arch Gen Psychiatry 2006;63:168-174.
ABSTRACT | FULL TEXT  

Copper Perturbation in 2 Monozygotic Twins Discordant for Degree of Cognitive Impairment
Squitti et al.
Arch Neurol 2004;61:738-743.
ABSTRACT | FULL TEXT  

Hippocampal MRI volumetry in cognitively discordant monozygotic twin pairs
Jarvenpaa et al.
J. Neurol. Neurosurg. Psychiatry 2004;75:116-120.
ABSTRACT | FULL TEXT