Adult Changes in Thought Study

Biennial Study Visit Data

Data Description

The Adult Changes in Thought (ACT) Study biennial visit dataset contains all baseline study visits (N=5,763), biennial in-person follow-up visits (20,826), and telephone follow-up visits (N=1,158) ever completed by ACT participants as of the current data freeze date March 5, 2020. This constitutes a total of 27,747 visits spanning 1994 through the freeze date. A cumulative total of 1,347 ACT participants developed dementia over that time period.

This dataset includes one row per visit and contains only a limited set of demographic and administrative variables along with information of study outcomes (e.g., dementia diagnosis, etc.). It is meant to serve as the core starting file to which other datasets, including the individual study forms described below, are linked.

Study Forms

Research staff collect ACT participant information at study visits on paper forms. Each of these study forms collect specific domains of data. Form contents have changed over the years — some individual question items have changed, while others have been discontinued or added. Entirely new forms have also been added over the years and others discontinued. 

A summary list of the standard study forms collected at ACT baseline and biennial follow-up visits are provided below.

Baseline and Biennial Visits

These forms have been collected on ACT participants at in-person visits over the entirety of the ACT Study (1994 to present) unless otherwise specified:

  • Form 71 – Administrative 
  • Form 72 – Vision, Hearing, and Olfaction 
  • Form 73 – Memory and Functioning
  • Form CES-D – Center for Epidemiology Studies Depression Scale
  • Form 74 - Participant Comments
    • Collected at baseline visit only
  • Form 75 – Demographics 
  • Form 76 – Family History
    • Collected at baseline visit only and stopped collecting on new participants as of March 2017
  • Form 77 – Medical History 
  • Form 78 – Epidemiology 
  • Form 82 – Interviewer Assessment
    • Collected at baseline visit only
  • Form 84 – Cognitive Abilities Screening Instrument (CASI)
  • Form 85 – Blood Pressure and Neurology 
  • Forms 24/25 - Anthropometric and Early-Life
    • Only collected from ~1998 - 2005
  • Form 28 - Alcohol Drinking Questions
    • Only collected from ~1999 - 2004

If an ACT participant was unable to undergo one of their biennial visits, then the above forms were not collected. Instead, a check-in telephone visit was offered to collect a limited set of information from the following forms:

  • Form 68 – Telephone Follow-up 
  • Form 69 – Telephone versions of the CASI and Adult Lifestyles and Function Interview Mini-Mental State Examination (ALFI-MMSE)

Starting in April 2016, ACT participants were invited to complete a take-home questionnaire as part of their ACT Study visits to capture information on activities, sedentary behavior, sleep, falls, and various other elements:

  • Form 66 – Take Home Questionnaire 
    • Started offering in April 2016 and collection is ongoing 

Key Publications

The following publications provide additional detail on the biennial study visit data elements. These may be helpful supporting citations when publishing analyses using these data. 

  • Kukull WA, Higdon R, Bowen JD, McCormick WC, Teri L, Schellenberg GD, van Belle G, Jolley L, & Larson EB. (2002). Dementia and Alzheimer disease incidence: a prospective cohort study. Archives of Neurology, 59(11), 1737–1746. 
  • Larson EB, Wang L, Bowen JD, McCormick WC, Teri L, Crane P, & Kukull W. (2006). Exercise is associated with reduced risk for incident dementia among persons 65 years of age and older. Annals of Internal Medicine, 144(2), 73–81.  

Data Dictionary

An interim data dictionary is available to provide additional information about ACT data variables.