Betula - aging, memory and dementia

Summary

Strengths The Betula project has received funding for research infrastructures (large databases) from the Swedish Research Council. This means a major effort to make the Betula database available to researchers outside the project. The plan is that researchers granted access to Betula data will work against a closed system with terminals connected to a server to do their analyzes. The Betula Project is designed to make both cross-sectional and longitudinal analyses of the data for proper control of cohort effects, test-retest effects and effects of attrition. All participants are randomly sampled from the population registry of the city of Umeå. The attrition rate other than death is much lower in Betula than in any other ongoing study in the world. There is a very large number of variables used at each data collection (approximately 2000 variables). Weaknesses The data collections are very costly.

Type of data

Data Source
Survey

Type of Study
Survey different
Cohort study

Data gathering method
Face-to-face
Other: medical, physical and cognitive tests. Also genetic data and biological samples are connected to the Betula database.

Access to data

Conditions of access
Someone who wants to use Betula data will have to fill in an application according to what is shown below. The forms for such applications are called DTA (Data Transfer Agreement) and MTA (Material Transfer Agreement). These forms will be available here soon. It is shown in the forms which information that has to be provided and to whom the forms should be sent.

Type of available data (e.g. anonymised microdata, aggregated tables, etc.)
Anonymised microdata. But also Betula offers the possibility for external researchers to get access to data on cognition and health, blood and DNA samples, and neuroimaging data. For this to materialize some general considerations and specific rules need to be stated.

Formats available
Usually SAS, SPSS, Excel and texts (and others on request – see above)

Coverage

Coverage Years of collection, reference years, and sample sizes
The Betula Project is a longitudinal study of aging, memory and dementia. It has been going on in Umeå since 1988. In September 2013, a sixth data collection will begin. It is expected to be completed in March 2015. The participants of the project have been tested, interviewed and examined medically at five occasions (1988-1990, 1993-1995, 1998-2000, 2003-2005 and 2008-2010). The main objectives of the project is to study how memory functions and health change during adult life and old age, to identify risk factors for dementia and to identify early preclinical signs of dementia. Then the study began with including 1000 randomly selected individs from the Umeå municipality in the age groups 20, 35, 40, 45, 50, 55, 60, 65, 70, 75 and 80 years. It was 100 in each age cohort, and the gender distribution was similar to the population with about as many men as women in the younger age groups, and about twice as many women as men in the age groups 70 and over. Five years later, two more sample were included. The group has been monitored every five years: 1993, 1998, 2003 and 2008. A sixth wave of data collection is starting in September 2013. For each sample, each participant completed a thorough physical examination with blood tests of a nurse and a careful examination of a memory tester. There are data collected from approximately 4,700 participants. On each occasion, data for about 2000 variables were collected for each participant, which includes data on demographics, health, illness, medication, social and cognitive factors.

First year of collection
1998

Stratification if applicable
Mainly region of Västerbotten (around Umeå)

Base used for sampling

Geographical coverage and breakdowns
sample from City of Umeå

Age range
Individuals 20 to 80 years old; At present, those participants still alive in Betula are 25-100 years of age.

Statistical representativeness
Special group, please specify

Coverage of main and cross-cutting topics
The Betula project is a very multi-disciplinary research project with researchers from many different fields: psychology, neurophysiology, brain imaging, genetics, gerontology, computer simulations.

Linkage

Standardisation
The Betula project has not dealt with these standards and taxonomies. This is primarily a study on cognitive psychology, neuropsychology, brain imaging, genetics, neurophysiology, with many demographic variables like gender, age, education, illness of participants, illness of relatives, medication, life style, marital status etc.

Possibility of linkage among databases
Betula is used in many scientific settings (SWEDOLD, Linneaus database and many orhers) A running ID number of all participants exists. Participants are additionally identified by gender and age (in combination with the running ID number.)

Data quality

Entry errors if applicable
After each wave of data collection there is a careful quality check of the data collected. In addition, we do another quality check of the data now, when we are in the process of transferring the SPSS format to a MySQL format.

Breaks
The basic methodology design has been kept the same since the start of Betula in 1988. Some cognitive tests used originally have been deleted and others have been added primarily because of theoretical and methodological development in cognitive psychology, neuropsychology, neuroscience, brain imaging and other fields. Additional health tests have been added during the course of the project. For example, a very large sub-database has been added on oral health, bilingualism, hormones and women issues during menopause, cytokines, extensively on dementia, herpes virus, genetics (from single gene analyses to GWAS), brain imaging (structural and functional MRI, and PET data on some participants), for some social variables (primarily economic variables) we can connect to a database over the whole population of Sweden, in connection with another database we can relate Betula data to an extensive database on health and nutrition, in connection with still another database we can connect Betula participants to cause of death and diseases. We have also blood saved from 1988and saliva saved saved from 2005.

Consistency of terminology or coding used during collection
Terminology is the same since 1988, except from a few cognitive tests that are classified differently now as compared to 1988 due to the development of theory and methodology in the field.

Governance

Contact information
Lars-Göran Nilsson, principal investigator
Department of Psychology / Stockholm University

106 91 Stockholm Sweden Phone: +46-8-163940
Email: lgn(at)psychology.su.se
Url: http://www.betula.su.se/en/

Timeliness, transparency
Depends due to number of ongoing studies. Usually one year or more.