Study Design

LASI-DAD draws a sub-sample of 4,000 respondents from the baseline LASI sample at age 60 or older. In collaboration with the Regional Geriatric Centers (RGCs), we interview the respondents either at their homes or at the participating hospitals, reaching out to both rural and urban areas in 18 states across the country, representing the country as a whole.

In selecting the study sample, we examine their cognitive test performance during the baseline LASI study and the proxy interviews for those who did not participate in the cognitive tests and identify those who are at high risk of cognitive impairment. We then oversample those at high risk and also recruit those at low and very low risk.

We administer the following list of cognitive tests:

  1. Hindi Mental State Exam
  2. HRS TICS
  3. Word Recall (Learning)
  4. Digit Span Forward and Backward
  5. Symbol Cancellation
  6. Word Recall (Delayed)
  7. Word List (Recognition)
  8. Logical Memory
  9. Constructional Praxis
  10. Logical Memory (Delayed)
  11. Logical Memory (Recognition)
  12. Retrieval Fluency
  13. Constructional Praxis (Recall)
  14. Executive Function
  15. Judgement & Problem Solving
  16. Serial 7s
  17. CSI-D
  18. RAVEN's
  19. Go-NoGo Task

The informant is someone who knows the respondent well, interacts with him/her frequently, and therefore knows his/her ability to complete daily functions and can report on them. Informants are most likely to be spouses, partners, children, or caregivers. Occasionally, they may be other relatives, friends, or neighbors.

The informant report includes:

  1. Demographics: asks about the informant's demographic characteristics and relationship with the respondent
  2. JORM IQCODE: asks about changes they observed about the respondent's cognitive abilities and memory compared to 10 years ago
  3. Blessed Scale Part 2: asks questions about the respondent's ability to take care of himself/herself without assistance from anyone or with some level of assistance
  4. Activities: asks about activities the respondent is doing, the frequency with which they are doing these activities, and whether they are doing them alone or with someone else
  5. Affect section: asks about the feelings the respondent experienced during his/her day while doing various activities
  6. CSI-D module: asks about the level of decline the respondent experienced while doing various daily activities in the past few years
  7. Blessed Scale Part 1: asks about the respondent's loss of ability

We assess the respondent's physical, mental, and functional health. Our geriatric assessment includes:

  1. Anthropometry: height, weight, mid-arm circumference, calf circumference
  2. Blood pressure and pulse
  3. Functional health: activities of daily living, instrumental activities of daily living
  4. Timed up and go test
  5. Mental health: Center for Epidemiological Studies - Depression, Beck's Anxiety Inventory
  6. 6-Minute walk test
  7. Mini Nutritional Assessment
  8. Hearing test
  9. Venous blood collection

Through the use of magnetic resonance imaging (MRI), we aim to better understand cognitive aging and impairment. We have obtained brain images from a subsample of LASI-DAD respondents.

Each individual going through MRI testing will receive numerous structural and functional MRI scans, according to the recently developed Laboratory of Neuro Imaging (LONI) Alzheimer's Disease Neuroimaging Initiative (ADNI) 3 protocol. Scan sequences such as T1, T2, DTI, and FLAIR allow us to better comprehend the presentation and physical development of MCI and dementia, while resting state fMRI will be used to help decipher functional differences that develop as these individuals begin to lose cognitive functionality.

Structural and functional images will be collected and compared with the other areas of our study, including genetics, cognitive and behavioral testing, and blood biomarkers. Ultimately, our goal is to first obtain a rich data set that details the initiation and progression of mild cognitive impairment and dementia. Afterwards, our aim is to better correlate the presentation and progression of the disease with the other areas of the project to give us a better understanding as to how structural and functional data aligns with behavioral and cognitive deficits.

Genomics has been one of the key initiatives of the LASI-DAD study, since the study's inception. As the first step under this initiative, we conducted a whole genome sequencing (WGS) validation study, demonstrating the feasibility and quality of sequencing. We then genotyped 960 geographically dispersed LASI-DAD respondents, using the Illumina Infinium Global Screening Array-24 v2.0 (GSA) BeadChip. It contains over 640,000 genetic markers, including highly optimized multi-ethnic genome-wide content, curated clinical research variants, and QC markers. The GSA data will be released to the wider research community later this year. Currently, we are in the process of preparing whole genome sequencing and population genetic analyses of 2,800 participants from 18 states and union territories of India.