We studied the correlation between the caregiver's feelings of burden and the cognitive, behavioral and functional impairment of demented patients. We attempted to show the influence of caregiver's feelings of burden on their perception of the patients' functional status and to establish the predictors of feelings of burden. Twenty-five probable Alzheimer disease patients (NINCDS-ADRDA criteria) were assessed on cognitive measures and functional status (DAFS). The caregiver's index of burden (CIB), obtained from an adapted version of the Zarit Burden Interview, was correlated with the caregiver's report on the patient's instrumental activities of daily living (IADL) and physical self-maintenance functions (ADL); total and partial DAFS scores, and patient's cognitive and behavioral problems rated with the Functional Dementia Scale (FDS). The CIB correlated with the caregiver's report on the patient's behavioral disturbances (r = 0.71, p < 0.001) and physical self-maintenance activities (r = 0.62, p < 0.001), but not with cognitive impairment, IADL and the DAFS. The patients showed better functional performance in the direct assessment than in that reported by their caregivers (mainly in shopping, feeding, dressing, and ambulation). Thus, burden may foster a growing intolerance of the caregiver, inducing an underestimation of the patient's actual functional competence. The caregiver's report on the patient's behavioral problems was the best predictor of feelings of burden (F = 19,9, p < 0.001). We emphasized the utility of the DAFS for a more objective assessment of functional status, treatment of the patient's behavioral problems to lessen the caregiver's feeling of burden, and the assessment and control of the caregiver's burden to highlight the need for medical assistance or support groups.

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Pigeons and goldfish were trained in red-green discrimination in daily sessions, with the rewarded color changed every 2 days. Improvement in the performance of the pigeons could be traced to decrements in retention from each day to the next. The goldfish showed no improvement and no decrements in retention. The results suggest that progressive improvement in habit reversal is a product of proactive interference, and that the absence of improvement in the fish is due, not to the lack of some higher-order process which operates to produce improvement in higher vertebrates, but to a difference in learning-retention mechanisms.

5 groups of rats were trained in discrete trials to press a retractable lever. 1 group was consistently reinforced; for the other 4 (partially reinforced) groups, percentage and distribution of reinforcement were varied factorially. 2 effects of partial reinforcement appeared in the data of extinction: 1 which distinguished the consistent from all partial groups early in extinction, and a second which distinguished among the partial groups much later in extinction. For the partial groups, resistance to extinction increased with number of successive nonreinforcements in training, but it was not significantly affected by percentage of reinforcement alone, or by total number of nonreinforcements in training.

Two experiments are reported in which goldfish failed to show the inverse relation between resistance to extinction and amount of reward and failed also to show the depression effect under conditions analogous to those which most clearly produce these effects in rats.