P1-549 UNDERSTANDING THE MOTIVATIONS, OBSTACLES ANDWAYS TO INCREASE ENGAGEMENT IN ONLINE STUDIES OF ALZHEIMER’S DISEASE: PRELIMINARY RESULTS FROM THE HEALTHY BRAIN PROJECT Lisa Bransby 1 , Alexandra Lavale 2 , David Baxendale 2 , Matthew P. Pase 3 , Nawaf Yassi 4,5 , Rachel F. Buckley 3,6,7 , Yen Ying Ying Lim 3 and The Healthy Brain Project Research Group, 1 Florey Institute of Neuroscience and Mental Health, Parkville, Australia; 2 The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia; 3 The Florey Institute of Neuroscience and Mental Health, Parkville, Australia; 4 The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia; 5 The University of Melbourne, Melbourne, Australia; 6 Harvard Medical School, Boston, MA, USA; 7 Massachusetts General Hospital, Boston, MA, USA. Contact e-mail: lisa.bransby@florey.edu.au Background: It is well established that Alzheimer’s disease (AD) can remain clinically silent for many decades, despite abnormal accumulation of AD proteinopathies. Many studies are now recruit- ing middle-aged adults to understand and characterise the nature of the disease in this very early stage. As AD is often viewed as a dis- ease of aging, the continued engagement of middle-aged adults in such studies can be challenging. One method has been to use online platforms to recruit, monitor and assess participants. We surveyed a large sample of middle-aged adults with a first- or second-degree family history of dementia to understand their motivations for participation, obstacles that may prevent their continued participa- tion, and methods of increasing participation and engagement in online studies. Methods: A total of 953 cognitively normal adults aged 40-70 with a first- or second-degree family history of demen- tia completed a series of questionnaires. Participants were asked whether they were generally motivated to participate in medical research, obstacles that may prevent them from participating, and methods of increasing participation and engagement in the future. Results: The most common obstacles for participation were time commitment (42%), inconvenience (28%), and not being aware of opportunities to participate (28%). The most common reason for participating in the Healthy Brain Project was a family history of dementia (51%) and the opportunity to help advance AD research (45%). To remain engaged, participants have indicated that they would like to receive personalised progress reports (84%) and reminder emails (64%). Most participants were willing to provide a saliva sample (83%) undergo neuroimaging and blood assessments (w74%). Most participants (73%) have also indicated that they would like to receive testing results even if they are used for research only and not clinically useful. Conclusions: Our results provide an important insight into factors that motivate middle-aged adults in participating in AD research. They also support the use of online platforms as a tool to recruit for more detailed biomarker as- sessments. Given the overwhelming interest in learning about test results, future research will need to focus on understanding the ethical implications of disclosure and best-practice methods of providing this information. P1-550 REFINING A LATENT DEMENTIA INDICATOR FOR A MULTI-STUDY CONSORTIUM Susan E. Luczak 1 , Christopher R. Beam 1 , Chandra A. Reynolds 2 , Matthew S. Panizzon 3 , Margaret Gatz 1 , the IGEMS Consortium, 1 University of Southern California, Los Angeles, CA, USA; 2 University of California, Riverside, Riverside, CA, USA; 3 University of California, San Diego, La Jolla, CA, USA. Contact e-mail: luczak@usc.edu Background: A variety of dementia indicators have been proposed in lieu of clinical diagnoses, ranging from cutoff scores on a cogni- tive screening measure such as MMSE to weighted combinations of cognitive test scores. Latent variable dementia indicators, “delta” (d), are reliable predictors of dementia risk (Gavett et al., Peh et al., Royall & Palmer). d reflects variance in a set of cognitive and functional ability indicators beyond variance already accounted for by a g’ factor solely indicated by cognitive scores. We built on this approach in a sample where clinical diagnoses were avail- able for testing the validity of d. Further, we used the twin sample to derive the genetic correlation between d and clinical diagnosis. Methods: We used confirmatory factor analysis to derive d and gen- eral cognitive ability residual (g’) scores for 1,471 individuals (39% demented) from the Study of Dementia in Swedish Twins (HAR- MONY). Functional ability and memory loaded onto d, but not g’. We fit a bivariate Cholesky model to 631 twin pairs (249 MZ; 382 DZ) to construct the genetic correlation between d and clinical diagnosis. Results: Delta more strongly correlated with dementia diagnoses than did g’ (r ¼ -.78 vs. r ¼ -.12). The genetic correlation between d and clinical diagnosis was -.77 (SE ¼ .14, p < .001). Conclusions: A latent dementia factor, comprised of memory, func- tional ability, and cognitive functioning has more predictive valid- ity for dementia risk compared with a residual general cognitive ability factor. The same genetic sources of variance strongly contribute to both d and clinical diagnosis. Genetic influences un- derlying dementia account for approximately 60% of genetic vari- ance in d. This approach provides a way to reconcile studies that use varying measures of cognitive, functional, and memory abilities. Results advance the conceptualization of a latent dementia model in differentiating g’ to represent a unique cognitive ability factor, from d as a construct that strongly overlaps with dementia risk. This study highlights the utility of a continuous dementia construct that provides greater power and variance to test genetic models than dichotomous clinical diagnoses or dichotomous indicators. Fund- ing: NIH Grant No. R01 AG060470. P1-551 “MEMORY RESEARCH: IS IT RIGHT FOR ME?” A VIDEO/PEER ROLE MODEL INTERVENTION TO CHANGE RESEARCH ATTITUDES AMONG ELDERLY MINORITIES Mari Umpierre 1 , Judith Neugroschl 1 , Margaret Sewell 1 , Carolyn W. Zhu 1,2 , Nelly Velasco 1 , Shehan Chin 3 , Sabrina Gonzalez 4 , Gabriela Silva 5 , Mitchell Bayne 6 , Luca Bianchetti 7 , Mary Sano 8,9 , 1 Icahn School of Medicine at Mount Sinai, New York, NY, USA; 2 James J. Peters VA Medical Center, Bronx, NewYork, USA; 3 Icahn School of Medicine, New York, NY, USA; 4 Cornell University, Ithaca, NY, USA; 5 City University of NewYork, New York, NY, USA; 6 Icahn School of Medicine, New York, NY, USA; 7 University of Brescia, Brescia, Italy; 8 Department of Psychiatry, Alzheimer’s Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA; 9 James J. Peters VA Medical Center, New York, NY, USA. Contact e-mail: mari.umpierre@mountsinai.org Background: Minorities are underrepresented in dementia research. Educational videos and peers may encourage research participa- tion. In a previous study (JAD 2016, 53:69–72) we assessed research attitudes in urban poor minority elders attending senior Poster Presentations: Sunday, July 14, 2019 P483