Cognitive function, mood and P3 latency: effects of the amelioration of anemia in dialysis patients.

Attention difficulties and psychomotor slowing associated with depressed mood affect the ability of individuals to perform on most neuropsychological tests. It has been suggested that latency of the P3 (P300) component of the event-related EEG potential is an index of neurocognitive status which is not affected by mood. Dialysis patients, who experience diminished dysphoric mood with the reversal of anemia when treated with recombinant human erythropoietin (rHuEPO), were tested for neurocognitive performance, mood and latency of P3. Prior to rHuEPO treatment mood was dysphoric, and neurocognitive testing showed mild deficits, but P3 latency was normal. After treatment, mood improved and neurocognitive test performance was normal. P3 amplitude increased over frontal areas, while P3 latency remained unchanged. Thus, in the case of dysphoric mood, P3 latency may provide a more accurate index of cognitive capacity (as opposed to level of functioning) than neurocognitive test measures.