Given the improvement in mortality rates associated with breast cancer, the importance of understanding the long-term neuropsychological consequences of chemotherapy is becoming increasingly vital. This study applies meta-analytic techniques to the scant literature on the relationship between contemporary adjuvant chemotherapy treatment for breast cancer and cognitive dysfunction as examined through neuropsychological indices. Seven studies (involving more than 300 participants) were selected from over 200 potential articles, based on three inclusion criteria: presence of breast cancer, administration of chemotherapy treatment, and use of neuropsychological tests. From these, nine treatment-control comparisons were used to generate 129 Hedge's d effect sizes across the cognitive domains of simple attention, working memory short- and long-term memory, speed of processing, language, spatial abilities, and motor function. Small to medium cumulative effect sizes, showing diminished cognitive function for chemotherapy treatment groups compared to control groups, were obtained for each of the eight cognitive domains. Overall, these results suggest that women who undergo adjuvant chemotherapy as treatment for breast cancer may experience subtle yet consequential cognitive decline.

These data suggest that hormonal therapies exert a subtle negative influence on cognition in breast cancer patients. Further analyses indicated that this effect was not fully accounted for by demographic factors or fatigue. Methodological limitations of the current study are addressed, along with recommendations for future studies in this area.

Younger age was associated with more FCR among breast cancer patients, regardless of motherhood status. Our findings suggest new, potentially valuable ways of managing FCR by helping affected people to reduce anxiety and illness intrusiveness.

These data suggest that there is a subtle negative impact of chemotherapy on cognitive function in breast cancer patients shortly following completion of treatment, but that this resolves within 1 year. However, given that our control group comprises breast cancer patients receiving hormonal therapy, and indications that hormonal therapy may also adversely affect cognition, such conclusions must be considered tentative.

These data support previous findings of a subtle negative influence of chemotherapy on cognitive function in a subgroup of breast cancer patients. The results are discussed in terms of the importance of study design.

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Rats lever pressed for concurrent electrical stimulation of the lateral hypothalamus and ventral tegmentum. The pulse-pair stimulation technique was used, with the first pulse of each pair applied to one electrode and the second to the other electrode; the intrapair interval was varied. The effectiveness of stimulation, measured behaviorally, increased abruptly (within .4 msec) as the intrapair interval was increased in the range from 1.0 to 2.0 msec These results, which do not resemble single-electrode refractory period results, are interpreted as evidence of collision in the directly stimulated, reward-related neurons linking the two sites. We conclude that self-stimulation of the medial forebrain bundle involves the direct activation of long-axon, longitudinal pathways. Estimates of the conduction velocity in the fibers subserving the collision-like effects are consistent with the properties of small myelinated axons but not central monoaminergic fibers.

The role of ascending and descending fibers in self-stimulation of the lateral hypothalamus and ventral tegmental area in the rat was assessed by noting whether anodal hyperpolarization of one of these sites could reduce the rewarding effect of stimulating the other site. Strength-duration curves were obtained by psychophysical means, with one of the depth electrodes serving as the cathode and the other as the anode. It was anticipated that at long pulse durations, conduction in some of the fibers stimulated at the cathode would be blocked at the anode. At shorter durations, the anodal hyperpolarization should have dissipated before the arrival of the action potentials triggered by the cathode. Thus, the predicted effect of the block was to bend the strength-duration curves obtained with two depth electrodes upward at long pulse durations, provided that the anode lay between the cathode and the efferent stages of the pathway responsible for the rewarding effect. To control for possible differences in the density of the reward substrate in the lateral hypothalamic and ventral tegmental areas, the strength-duration curves obtained with a given cathode and a depth anode were compared to curves obtained with the same cathode but with an anode consisting of a set of skull screws. It was expected that the concentrated current entering from the depth anode would much more effectively block conduction in the medial forebrain bundle than the diffuse current entering from the large, distant skull screws. The predicted change in the shape of the strength-duration curves was observed only when the ventral tegmental electrode served as the anode and the lateral hypothalamic electrode as the cathode. This is consistent with the notion that in at least some of the neurons responsible for the rewarding effect, action potentials elicited by the lateral hypothalamic electrode had to pass through the ventral tegmental area in order to reach the efferent stages of the reward pathway. In the simplest anatomical arrangement consonant with this view, the somata of these cells lie in the forebrain and give rise to descending axons. As a test of the hypothesis that anodal block was responsible for changing the shape of the strength-duration curve obtained with the ventral tegmental anode, a psychophysical version of the collision test was used to determine whether the tips of the lateral hypothalamic and ventral tegmental electrodes were indeed linked by a common set of reward-related fibers.(ABSTRACT TRUNCATED AT 400 WORDS)