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Introduction: Schizophrenia patients perform below the norm on verbal fluency tests. The causes for this are unknown, but defective memory, executive functioning and psychomotor speed may play a role. Method: We examined 50 patients with schizophrenia and related disorders, and 25 healthy controls with a cognitive test battery containing tests for verbal memory, executive functioning and psychomotor speed, and a categorical fluency test. Results: Patients obtained significantly lower test results than the controls on most cognitive measures including the verbal fluency test. During the fluency test, they formed as many clusters, and switched as often between clusters as the controls did, but they generated fewer words per cluster. Interestingly, in the control group, fluency performance was predicted by memory and executive functioning, but not by psychomotor speed. In patients, verbal fluency was predicted by psychomotor speed, but not by memory or executive functioning. Discussion: We conclude that psychomotor speed could be a crucial factor in cognition, and its influence on cognitive test performance should be considered in schizophrenia research. Furthermore, these data illustrate the importance of qualitative analysis of cognitive impairments in schizophrenia patients, as traditional cognitive tests often only provide quantitative information.

Objective. The aim of this study was to examine the effects of transcutaneous electrical nerve stimulation (TENS) on cognition, behavior, and the rest-activity rhythm in children with attention deficit hyperactivity disorder, combined type (ADHD-CT). Methods. Twenty-two children diagnosed with ADHD-CT received TENS treatment during 6 weeks, 2 times 30 min a day. Neuropsychological tests were administered to assess cognition, parent/teacher behavioral rating scales were used to measure behavior, and actigraphy was used to assess the rest-activity rhythm. Results. TENS appeared to have a moderate beneficial influence on cognitive functions that load particularly on executive function. There was also improvement in behavior as measured by parent/teacher behavioral rating scales. Moreover, motor restlessness during sleep and motor activity during the day decreased by TENS. Conclusions. The effects of TENS in children with ADHD are modest but encouraging and warrant further research. © 2004, Sage Publications. All rights reserved.

In previous studies, transcutaneous electrical nerve stimulation (TENS) improved cognition and behaviour in patients with Alzheimer's disease (AD). The rationale underlying these studies was that TENS could activate, e.g. the septo-hippocampal region and the hypothalamus through direct and indirect pathways. As these areas are also affected in normal aging, the present study examined the effects of TENS on cognition and behaviour in nondemented elderly persons. The results suggest an improvement in visual short-term and verbal long-term (recognition) memory, and semantic verbal fluency. Moreover, stimulated elderly persons felt less depressed. Limitations are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.