P3‐404: Relationship between patient dependence on others and clinical measures of cognition, function and behavior in Alzheimer's disease (AD): Results from a longitudinal study

Dependence on others for care needs has been recommended as a unifying construct in defining severity in AD. Much of the support for the dependence construct has been based on cross-sectional data showing relationships between dependence, measured using the Dependence Scale (DS), and clinical measures of cognition, function and behavior. The objective of this study is to measure how these relationships change over time. An analysis of data from participants with AD enrolled in a longitudinal observational study from 39 study sites across the United States and Europe, was conducted. The study was conducted between 2006 and 2009 and the entry criteria were similar to those used in the Alzheimer's Disease Neuroimaging Initiative (ADNI). The DS (range 0-15), and measures of cognition, Mini Mental State Inventory (MMSE; range 0-30), function, Disability Assessment for Dementia (DAD; range 0-40) and behavior, Neuropsychiatric Inventory (NPI; range 0-144) were administered at 6-monthly intervals. The relationship between changes in the DS over 1 year and changes in MMSE, DAD and NPI was examined for patients with concurrent DS, and the 3 clinical measures at 2 time points, one year apart, using Pearson correlation coefficients. In addition, a repeated measures model examined the relationship between the DS and the three clinical measures over 3 sequential, 6-month time points. 196 participants with AD were recruited in this study. The mean score changes for the DS, MMSE, DAD and NPI over the 1 year interval examined were 0.83 (N=69),-1.50 (N=142), -7.55 (N=140), 0.93 (N=138), respectively. Significant correlations between the change in DS summated score and changes in MMSE (r=-0.38; p < 0.005), DAD (r=-0.37; p < 0.005) and NPI (r = 0.29; p < 0.05). The repeated measures models confirmed significant relationships between the DS and MMSE (DS=10.6778 - 0.2599*MMSE, p < 0.0001), DAD (DS=11.1167 - 0.08222*DAD, p < 0.0001) and NPI (DS = 4.6392 + 0.08851*NPI, p < 0.0001). The relationships observed in previously published cross-sectional analyses were confirmed longitudinally. These data further support the concept of dependence on others for care needs as a potential method of translating the effect of changes in cognition, function, and behavior into a more holistic description of AD progression.