Trajectories of behavioral disturbance in dementia.

Predicting the progression of dementia is a challenge for clinicians yet this information is highly valued by patients' families. An informally observed 4-stage model of dementia can be helpful in educating caregivers and preparing them for what lies ahead. In the behavioral variant of frontotemporal dementia (bvFTD), this model describes the evolution of behavioral disturbances and is characterized by an inflection point between stage 2 (progressively severe behavioral aberration) and stage 3 (increasing apathy and remission of behavior problems). In this study, we sought evidence for this model using a database of serial Neuropsychiatric Inventory (NPI) scores for 45 patients with FTD and 47 patients with Alzheimer's disease (AD). We transformed the NPI scores into a single variable for each participant that represented the yearly rate of change in total NPI score and used this as the dependent variable in a multivariate linear regression. Age at onset of dementia, NPI score at initial visit, and duration of illness at first NPI all contributed significantly to the regression model in the bvFTD group. Participants with an initial NPI acquired before 6 years of disease duration tended to have a more positive rate of change in NPI total score (representing worsening behavioral disturbances) than those with an initial NPI performed after 6 years. None of the aforementioned variables were significantly associated with yearly change in NPI total score in the AD group. These results support a crescendo-decrescendo trajectory of behavioral symptoms in bvFTD but do not suggest that there is a similar pattern in AD, and further longitudinal data collection is necessary.