Statistical Methodological Issues in Handling of Fatty Acid Data: Percentage or Concentration, Imputation and Indices

Basic aspects in the handling of fatty acid-data have remained largely underexposed. Of these, we aimed to address three statistical methodological issues, by quantitatively exemplifying their imminent confounding impact on analytical outcomes: (1) presenting results as relative percentages or absolute concentrations, (2) handling of missing/non-detectable values, and (3) using structural indices for data-reduction. Therefore, we reanalyzed an example dataset containing erythrocyte fatty acid-concentrations of 137 recurrently depressed patients and 73 controls. First, correlations between data presented as percentages and concentrations varied for different fatty acids, depending on their correlation with the total fatty acid-concentration. Second, multiple imputation of non-detects resulted in differences in significance compared to zero-substitution or omission of non-detects. Third, patients’ chain length-, unsaturation-, and peroxidation-indices were significantly lower compared to controls, which corresponded with patterns interpreted from individual fatty acid tests. In conclusion, results from our example dataset show that statistical methodological choices can have a significant influence on outcomes of fatty acid analysis, which emphasizes the relevance of: (1) hypothesis-based fatty acid-presentation (percentages or concentrations), (2) multiple imputation, preventing bias introduced by non-detects; and (3) the possibility of using (structural) indices, to delineate fatty acid-patterns thereby preventing multiple testing

Examining techniques for measuring the effects of nutrients on mental performance and mood state

Purpose: Intake of specific nutrients has been linked to mental states and various indices of cognitive performance although the effects are often subtle and difficult to interpret. Measurement of so-called objective variables (e.g. reaction times) is often considered to be the gold standard for assessing outcomes in this field of research. It can, however, be argued that data on subjective experience (e.g. mood) are also important and may enrich existing objective data. The aim of this review is to evaluate methods for measuring mental performance and mood, considering the definition of subjective mood and the validity of measures of subjective experience. Methods: A multi-stakeholder expert group was invited by ILSI Europe to come to a consensus around the utility of objective and subjective measurement in this field, which forms the basis of the paper. Therefore, the present review reflects a succinct overview of the science but is not intended to be a systematic review. Results: The proposed approach extends the traditional methodology using standard ‘objective’ measurements to also include the consumers’ subjective experiences in relation to food. Specific recommendations include 1) using contemporary methods to capture transient mood states; 2) using sufficiently sensitive measures to capture effects of nutritional intervention; 3) considering the possibility that subjective and objective responses will occur over different time frames; and 4) recognition of the importance of expectancy and placebo effects for subjective measures. Conclusions: The consensus reached was that the most informative approach should involve collection and consideration of both objective and subjective data

Effects of short-term varenicline administration on emotional and cognitive processing in healthy, non-smoking adults: a randomized, double-blind, study.

Varenicline is an effective and increasingly prescribed drug for smoking cessation, but has been associated with depressive symptoms and suicidal behavior. However, it remains unclear whether those changes in mood and behavior are directly related to varenicline use, or caused by smoking cessation itself or reflects depression and suicidality rates in smokers, independent of treatment. To investigate the influence of varenicline on mood and behavior independent of smoking and smoking cessation, we assessed the effects of varenicline on emotional processing (a biomarker of depressogenic effects), emotion-potentiated startle reactivity, impulsivity (linked with suicidal behavior), and cognitive performance in non-smoking subjects. We used a randomized, double-blind design, in which we administered varenicline or placebo to healthy subjects over 7 days (0.5 mg/day first 3 days, then 1 mg/day). Cognitive and emotional processing was assessed by a battery of computerized tasks and recording of emotion-potentiated startle response. A total of 41 subjects were randomized, with 38 subjects included in the analysis. The varenicline group did not differ from placebo in terms of negative biases in emotional processing or mood. However, compared with placebo, the varenicline group scored higher on working and declarative memory. In conclusion, short-term varenicline use did not influence negative biases in emotional processing or impulsivity in non-smoking subjects, thereby not supporting direct depressogenic or suicidal risk behavior-inducing effects. In contrast, varenicline may have cognitive-enhancing effects

Effects of short-term varenicline administration on cortisol in healthy, non-smoking adults: a randomized, double-blind, study.

RATIONALE: Varenicline is the most effective drug for smoking cessation, but its use decreased because of reports of depressogenic side effects. However, because smoking and smoking cessation on their own are associated with depression, it remains unclear whether reported depressogenic effects are attributable to varenicline, or to smoking, and/or smoking cessation themselves. OBJECTIVES: Previously, we observed no depressogenic effects of varenicline on a psychological level. In the present study, we aimed at investigating potential depressogenic effects of the partial nicotinergic acetylcholine receptor agonist varenicline on a biological level. A possible pathway would be an effect of varenicline on the hypothalamic-pituitary-adrenal (HPA) axis, considering the relation between the HPA axis and (1) the cholinergic system and (2) depression. METHODS: In a randomized, double-blind design, we administered varenicline or placebo for 7 days (0.5 mg/day first 3 days, then 1 mg/day) to healthy never-smoking subjects, thereby eliminating bias by (previous) smoking status. We used repeated measures (before and after treatment) of the salivary free cortisol awakening response to measure HPA axis activity and flexibility. RESULTS: Salivary cortisol data of 34 subjects were included in the analysis. Results showed no effect of varenicline on height (F₁,₃₂ = 0.405; P = 0.529) or shape (F₂,₃₁ = 0.110; P = 0.164) of the cortisol awakening response. CONCLUSIONS: Results do not suggest depressogenic effects of varenicline on the HPA axis. Although this does not preclude other biological depressogenic effects of varenicline, it seems that concerns about effects of varenicline on the HPA axis should not limit its potential to treat nicotine and related addictions

Associations Between Daily Affective Instability and Connectomics in Functional Subnetworks in Remitted Patients with Recurrent Major Depressive Disorder

Remitted patients with major depressive disorder (rMDD) often report more fluctuations in mood as residual symptomatology. It is unclear how this affective instability is associated with information processing related to the default mode (DMS), salience/reward (SRS), and frontoparietal (FPS) subnetworks in rMDD patients at high risk of recurrence (rrMDD). Sixty-two unipolar, drug-free rrMDD patients (>= 2 MDD episodes) and 41 healthy controls (HCs) were recruited. We used experience sampling methodology to monitor mood/cognitions (10 times a day for 6 days) and calculated affective instability using the mean adjusted absolute successive difference. Subsequently, we collected resting-state functional magnetic resonance imaging data and performed graph theory to obtain network metrics of integration within (local efficiency) the DMS, SRS, and FPS, and between (participation coefficient) these subnetworks and others. In rrMDD patients compared with HCs, we found that affective instability was increased in most negative mood/cognition variables and that the DMS had less connections with other subnetworks. Furthermore, we found that rrMDD patients, who showed more instability in feeling down and irritated, had less connections between the SRS and other subnetworks and higher local efficiency coefficients in the FPS, respectively. In conclusion, rrMDD patients, compared with HCs, are less stable in their negative mood and these dynamics are related to differences in information processing within-and between-specific functional subnetworks. These results are a first step to gain a better understanding of how mood fluctuations in real life are represented in the brain and provide insights into the vulnerability profile of MDD