Uniform Data Set version 4
UDSv4 - Template

United States

Reference ID

USDv4

Producer(s)

National Alzheimer’s Coordinating Center (NACC) and the NIA-funded ADRC network

Collections

Clinical Trial

Metadata

DDI/XML JSON

Created on

Jul 02, 2026

Last modified

Jul 07, 2026

Page views

14351

Study Description
Data Dictionary

5d. B12 deficiency (b12def)

Data file: UDSv4TemplateForXMLD_2026-04-14_0731.REDCap.xml

Overview

Valid: 56

Range: -

Format:

Questions and instructions

Categories

Value	Category	Cases
0	Absent	19	33.9%
1	Recent/active	26	46.4%
2	Remote/inactive	9	16.1%
9	Unknown	2	3.6%

Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.

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