Dec 20, 2012

Study partners play critical role in clinical trials for Alzheimer's disease

A new UCLA study has assessed the prevalence of the various types of study partners in Alzheimer's clinical trials and has discovered that who the study partner is can actually impact the results of the trials and the interpretations of results.

UCLA Mary S. Easton Center for Alzheimer's Disease Research.

Clinical trials for Alzheimer's disease | Alzheimer's Reading Room

"In contrast, in our analyses, 67 percent of the 2,041 Alzheimer's clinical trial participants had a spouse as their study partner.

We found that there were several differences between people with spouse and adult child study partners that could affect the results of the trials and interpretations of those results."

The study appears in the Dec. 19 online issue of the journal Neurology.

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Effect of study partner on the conduct of Alzheimer disease clinical trials

The Objective

Alzheimer disease (AD) dementia clinical trials require 2 participants: a patient and a study partner. We assessed the prevalence of study partner types and how these types associate with patient-related outcome measures.


Retrospective analyses of 6 Alzheimer’s Disease Cooperative Study (ADCS) randomized clinical trials were conducted.

Study partners were categorized as spouse, adult child, or other.

Prevalence of study partner type and associations between study partner type and trial outcomes including study completion and placebo decline on the Mini-Mental State Examination, the Alzheimer’s Disease Assessment Scale–cognitive subscale, the Clinical Dementia Rating scale Sum of the Boxes score, and the ADCS–Activities of Daily Living were examined.


More participants (67%) enrolled with spouses than adult children (26%) or other study partners (7%).

Participants with spouse partners had a lower dropout rate (25%) than those with adult child (32%) or other study partners (34%); only the difference vs others was statistically significant.

Participants with adult child and other partners randomized to placebo performed worse at baseline than those with spouse partners on the ADCS–Activities of Daily Living (p = 0.04), but were not different at 18 months.

There were no differences at baseline for the Mini-Mental State Examination, Clinical Dementia Rating scale Sum of the Boxes score, or Alzheimer’s Disease Assessment Scale–cognitive subscale. In multivariate models of the rates of change over time among placebo participants, no differences among study partner groups reached statistical significance.


Patients with nonspouse caregivers less frequently participate in AD dementia trials. Increased enrollment of AD patients with nonspouse caregivers may require additional recruitment and retention strategies.

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