Alzheimer's Disease Education and Referral Center

Genetic Characterization of Dementia

Genetic Characterization of Dementia

Overall Status: 
Brief Description: 

The purpose of this observational study is to examine the genetic basis of dementia, which may help provide better tests and treatments for the condition. Investigators will interview individuals diagnosed with dementia, their family members, and healthy adults. Participants will provide blood samples for genetic testing and attend regular visits to monitor their brain health and function. Treatment will not be provided as part of the study.

Patient Qualifications: 
Min AgeMax AgeGenderHealthy Volunteers
18 Years
Accepts Healthy Volunteers
Inclusion Criteria: 
    • Previous diagnosis of dementia by a neurologist, other medical care provider, or researcher accompanied by sufficient clinical and/or laboratory evidence
    • Clinical confirmation of dementia by the investigator and his associates, either by direct examination and/or review of medical records
    • Family members of individual diagnosed with dementia
    • Healthy adult volunteers
Exclusion Criteria: 
    • Movement disorder secondary to a specific environmental exposure, birth injury, metabolic disorder, or brain infection such as encephalitis
Detailed Description: 

Dementia becomes more common with age, with a prevalence of 5 percent to 10 percent in people over age 65 and 20 percent in people over age 80. It is difficult to distinguish even the three most common types of dementia: Alzheimers disease, Lewy body disease and multi-infarct dementia. Alzheimer's, the most common form of dementia, is genetically complex. To date, mutations in three genes (APP, PSEN1, and PSEN2) have been identified as causes of familial early-onset Alzheimer's. In addition, a change in the apolipoprotein E (APOE) gene has been associated with the more common late-onset form of the disease. These four genes account for less than 30 percent of the genetic variance in age of onset for Alzheimer's disease. Numerous other genes that influence Alzheimer's risk may exist.

Another type of dementia, caused by Lewy body disease, accounts for 20 percent of all cases of dementia in old age. It can be associated with mutations in the alpha synuclein gene, but most Lewy body dementia is not. The ability to identify underlying genetic influences that result in different synuclein pathologies is key to understanding these disorders.

Investigators hope to gain a better understanding of the biochemical and physiological processes and complex genetic interactions underlying the diseases that cause dementia. Their first aim is to identify families with a history of dementia in an attempt to clone the causative gene defect(s). Their second aim is to investigate the association between genetic polymorphisms and dementia. This will be performed by a candidate gene approach, assessing the contribution of genes already associated with familial forms of disease, likely candidates, or genes within a genetic region previously linked to disease.

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Geolocation is 39.2713976, -76.5603828

National Institute of Aging, Clinical Research Unit
Lead Sponsor: 
National Institute on Aging (NIA)
Collaborator Sponsor: 
Facility Investigators: 
Andrew Singleton, PhD
Principal Investigator
National Institute on Aging (NIA)
Study Contact: 
Andrew Singleton, PhD
Locations ID 
NCT01867359 (follow link to view full record on in new window)
Official Title: 
The Genetic Characterization of Dementia
Study Start Date: 
March 2003
Study End Date: 
December 2016