No abstract

Acute tryptophan depletion (ATD) studies have been used to assess the role of the serotonergic system in various aspects of human behaviour. Changes in mood have already been described in selected groups of individuals submitted to ATD. The present study was a randomized, double-blind, cross-over trial designed to evaluate the effects of ATD on mood, memory, attention and induced anxiety in normal male volunteers. Twelve healthy male volunteers were submitted to two separate sessions of ATD, 1 week apart. Drinks containing either a balanced mixture of amino acids (B) or a similar mixture devoid of tryptophan (T-) were administered in each session. Mood was assessed using self-rating scales. Attention and memory were assessed using a battery of psychological tests. Anxiety induction was carried out using a simulation of public speaking. Blood levels of tryptophan were assessed before and after the B and T- drinks. Results showed that ATD markedly decreased plasma tryptophan (p < 0.0001). Mood ratings, memory and attention were not changed by the T- drink. There was no difference among the anxiety levels measured under T- or B mixtures. These data supports the notion that ATD does not change mood and cognitive function in healthy subjects.

Acute phenylalanine and tyrosine depletion (APTD) studies have been used to assess the role of the cathecholaminergic system in various aspects of human behaviour. In this study we conducted a randomized, double-blind, controlled and cross-over comparison to evaluate the effects of APTD on memory, attention and mood in normal subjects. Twelve healthy male volunteers were included in this study. The subjects ingested a nutritionally balanced mixture (B) or a similar mixture deficient in phenylalanine and tyrosine (PT-). Before and 5 h after ingestion of the drink, volunteers underwent tests on mood, memory and attention. Results of the memory tests showed that PT- mixture impaired word recall as measured in Rey's test (p = 0.016). The assessment of changes in mood showed that the balanced mixture improved scores of as alertness (VAMS factor I, p = 0.037) and the PT- mixture induces an opposite effect, increased scores of anxiety (Profiles of Mental State composed-anxious dimension, p = 0.022). These results suggest that tyrosine plasma levels and cathecholamines may be important factors in regulating mood and memory.

Executive functions and memory in bipolar disorders I and II: new insights from meta-analytic results.Objective: To perform a systematic review and meta-analysis of executive functions (EF) and episodic memory in bipolar disorder (BD). Methods: A literature search was conducted on three electronic databases. Results were combined using random-effects meta-analysis. Results: A total of 126 studies (6424 patients with BDI, 702 with BDII, and 8276 controls) were included. BDI was associated with moderate to large impairments across all cognitive functions and BDII with small-tomedium impairments. Small significant differences were identified between BDI and BDII on all cognitive functions except inhibition. The Trail Making Test (TMT) (g = 0.74, 95% CI: 0.67-0.80), Hayling Test (g = 0.58, 95% CI: 0.34-0.81), Digit Span Total (g = 0.79, 95% CI: 0.57-1.01), and Category Fluency (g = 0.59, 95% CI: 0.45-0.72) tasks were most sensitive to cognitive impairment in BDI. The TMT (g = 0.65, 95% CI: 0.50-0.80) and Category Fluency (g = 0.56, 95% CI: 0.37-0.75) were also sensitive to cognitive alterations in patients with BDII. Conclusion: BD type I was associated with more severe and widespread impairments than BDII, which showed smaller impairments on all functions except inhibition, where impairments were larger. Education and (hypo)manic symptoms should be further investigated in future studies due to their possible influence on the neuropsychological profile of BD. The instruments identified in this review should be considered for inclusion in cognitive assessment batteries in BD. Summations• Patients with BD type I performed worse than control subjects with moderate to large effect sizes, while patients with BD type II showed impairments with small-to-medium effect sizes. Small significant differences were identified between BD types I and II on all cognitive functions except inhibition.• Education, (hypo)mania symptom scores, and lithium use moderated cognitive impairments in BD.• The TMT B, Hayling Test B, Digit Span Total, and Category Fluency were most sensitive to cognitive impairments and to differences between cognitive performance in individuals with BD types I and II. Limitations• Small number of studies involving BD type II. • Large heterogeneity in effect sizes. • Inconsistent reporting of potential moderator variables (mood symptoms, medication use, comorbidities).