Caregiver perception of apathy in persons with mild cognitive impairment or Alzheimer's disease: a longitudinal study.

OBJECTIVE: Discrepancy between self- and caregiver apathy ratings was examined longitudinally for persons with mild cognitive impairment or Alzheimer's disease. Particular focus was on the distinction between the positive and negative caregiver bias and its predictive value for a clinical diagnosis of apathy.
METHOD: Apathy rating discrepancy was based on the apathy evaluation scale. Dyads were categorized depending on whether the caregiver reported fewer deficits (positive caregiver bias) or more deficits (negative caregiver bias) than the cognitively impaired person did.
RESULTS: Caregiver ratings and rating discrepancy showed a significant increase from baseline to follow-up. By contrast, self- and clinician ratings showed no change across the two time points. Ratings with a negative caregiver bias remained stable, while those with a positive caregiver bias showed a significant increase in the caregiver ratings but also a significant decrease in the self-ratings. A negative caregiver bias at baseline was significantly related to greater likelihood of having clinical apathy at follow-up, adjusted for an array of control variables.
CONCLUSION: Positive and negative caregiver bias should be distinguished, as they seem to reflect distinct dyadic processes and are relevant for clinical outcome. Furthermore, negative rating discrepancies can be considered a risk factor for developing apathy.