Isabelle Lussier

A double-blind, placebo-controlled study of the effects of lithium on cognition in healthy subjects: mild and selective effects on learning

BACKGROUND Several studies have shown cognitive impairment in short-term memory, long-term memory and psychomotor speed in bipolar patients taking lithium. The aim of the study was to look at the effect of lithium in normal subjects (N=30) taking lithium for 3 weeks. A comprehensive battery was used to assess attention and memory. METHODS Subjects were randomized to double-blind treatment with either lithium (N=15) or placebo (N=15) for a 3-week period. Thirteen participants in the lithium group and 15 in the placebo group completed the study. The lithium and placebo were administered twice daily in doses varying from 1050 to 1950 mg (mean=1569 mg). The initial daily dose was calculated according to the Pepin formula to achieve a blood serum lithium level of about 0.8 mmol/l. Cognitive performance (attention, memory) was assessed in each subjects during three periods, i.e. at baseline, after 3 weeks of lithium or placebo, and 2 weeks after discontinuation of study medication. RESULTS In short-term memory tasks, the performance of subjects in the lithium group was worst 3 weeks after lithium treatment compared to 2 weeks after discontinuation. In long-term memory, a significantly higher number of words was recalled by the placebo group but not the lithium group. CONCLUSIONS Lithium may have an effect on learning when long-term explicit memory test are administered repeatedly. It means that the practice effect when a subject performs the same task several times is less in the lithium-treated group than in the placebo group. This practice effect is related to the learning of a task.

The heterogeneity of memory dysfunction in schizophrenia.

Objective: To characterize the memory dysfunction of schizophrenic patients. Method: The components of the human memory system are described, and then a review of the various memory deficits identified among patients suffering from schizophrenia is presented. Finally, an overview of the latest developments in the comprehension of schizophrenia and a discussion on certain proposals advanced by various researchers in the field intended to shed light on the disorder is provided. Results: Schizophrenia appears to be an amalgamation of many different disorders. No single model for identifying the disorder has been able to encompass every aspect of schizophrenia. Conclusion: Future studies will need to consider new ways of selecting and grouping schizophrenic patients.

Double‐blind, placebo‐controlled study comparing effects of zopiclone and temazepam on cognitive functioning of insomniacs

The purpose of this study was to compare the cognitive effect of two medications frequently prescribed to patients suffering from insomnia. Using a double‐blind design, we evaluated three parallel groups of 20 insomniac patients treated over a period of 3 weeks with zopiclone, temazepam and placebo, respectively. Our hypothesis was that the impact of zopiclone 7.5 mg/day on cognitive functioning would be minimal 12 h after administration and that temazepam 30 mg/day would affect explicit memory, as is the case with other benzodiazepines. Patients were assessed at baseline following a 1‐week, single‐blind placebo‐intake period, and again at the end of each of the 3 weeks of the comparative phase. Then, in order to estimate the severity and duration of potential rebound insomnia, patients were again assessed following another 1‐week, single‐blind placebo‐washout period at the end of the 3 weeks of treatment. The overall duration of the study for each patient was thus 5 weeks. The instruments of measure used were the Hamilton scale for anxiety, daily self‐rating questionnaire for assessment of sleep onset, duration and quality, and two large batteries of psychometric tests. The first of these batteries assessed memory and included span tests for short‐term memory, cued recall tasks for long‐term explicit memory, and a word‐completion task for implicit memory; the second measured attention and concentration through the assessment of alertness, sustained attention and divided attention. The sleep and anxiety results obtained confirm the findings of previous research. Zopiclone and temazepam possess a clinically significant hypnotic activity, with no rebound insomnia or anxiety, during the week of drug withdrawal. The results indicate that the two hypnotic drugs studied have little impact on cognitive functioning. We can therefore conclude that at the doses administered over the 3 weeks, the two hypnotic drugs in question are relatively safe and efficacious in the treatment of insomnia and enable patients to enjoy a good quality of life. Copyright

The Effect of Risperidone on Cognitive and Psychopathological Manifestations of Schizophrenia

The purpose of this study was to evaluate the effect of risperidone on the cognitive functioning of patients with schizophrenia and how it relates to the alleviation of psychopathological symptoms usually observed in patients receiving treatment. Twelve schizophrenic patients were evaluated while being treated with a traditional neuroleptic, and again approximately 8 and 24 weeks after initiation of risperidone. Patients were compared with a group of normal controls (n=24) who underwent the same cognitive evaluation across time. The normal control group was included to evaluate the level of impairments in patients, but also to test for practice effects. The cognitive evaluation included measures of short-term and long-term memory; attention (alertness, sustained and selective); and executive functioning (verbal and category fluency). Clinical symptoms were rated on the Positive and Negative Symptoms Scale (PANSS) and the Brief Psychiatric Rating Scale (BPRS). Extrapyramidal symptoms were rated with the Extrapyramidal Symptoms Rating Scale. During treatment with risperidone, schizophrenic patients improved their BPRS and PANSS scores, their performance level on tests of alertness, and both sustained and selective attention.