The potential antidepressant properties of probiotics have been suggested, but their influence on the emotional processes that may underlie this effect is unclear.

Depressed volunteers (n = 71) were recruited into a randomised double-blind, placebo-controlled study to explore the effects of a daily, 4-week intake of a multispecies probiotic or placebo on emotional processing and cognition. Mood, anxiety, positive and negative affect, sleep, salivary cortisol and serum C-reactive peptide (CRP) were assessed before and after supplementation.

Compared with placebo, probiotic intake increased accuracy at identifying faces expressing all emotions (+12%, p < 0.05, total n = 51) and vigilance to neutral faces (mean difference between groups = 12.28 ms ± 6.1, p < 0.05, total n = 51). Probiotic supplementation also reduced reward learning (−9%, p < 0.05, total n = 51), and interference word recall on the auditory verbal learning task (−18%, p < 0.05, total n = 50), but did not affect other aspects of cognitive performance. Although actigraphy revealed a significant group × night-time activity interaction, follow up analysis was not significant (p = 0.094). Supplementation did not alter salivary cortisol or circulating CRP concentrations. Probiotic intake significantly reduced (−50% from baseline, p < 0.05, n = 35) depression scores on the Patient Health Questionnaire-9, but these did not correlate with the changes in emotional processing.

The impartiality to positive and negative emotional stimuli or reward after probiotic supplementation have not been observed with conventional antidepressant therapies. Further studies are required to elucidate the significance of these changes with regard to the mood-improving action of the current probiotic.

We aimed at examining the relation between stress markers (cortisol levels and state anxiety) with memory for emotional information in AD patients and in healthy elderly.

Baseline and changes in stress markers during memory testing were assessed in a sample of 98 elderly (46 mild-to-moderate Alzheimer's disease patients and 52 controls) recruited from dementia day centers and adult day centers, respectively.

Salivary cortisol, state anxiety, and measures of immediate recall and delayed recognition using the International Affective Pictures System.

Patients’ performance in memory tasks was not associated with either cortisol levels or anxiety. In controls, quadratic and linear associations were found between cortisol and immediate recall scores (total and bias, respectively). Besides, quadratic and linear associations were observed between anxiety and delayed recognition scores (total and bias, respectively).

The emotional memory of patients with Alzheimer´s disease is not related to stress markers as healthy older adults’ is. Future studies that include moderating variables are needed to explain the lack of association.

Decades of research have investigated the impact of clinical depression on memory, which has revealed biases and in some cases impairments. However, little is understood about the effects of subclinical symptoms of depression on memory performance in the general population.

Here we report the effects of symptoms of depression on memory problems in a large population-derived cohort (N = 2544), 87% of whom reported at least one symptom of depression. Specifically, we investigate the impact of depressive symptoms on subjective memory complaints, objective memory performance on a standard neuropsychological task and, in a subsample (n = 288), objective memory in affective contexts.

There was a dissociation between subjective and objective memory performance, with depressive symptoms showing a robust relationship with self-reports of memory complaints, even after adjusting for age, sex, general cognitive ability and symptoms of anxiety, but not with performance on the standardised measure of verbal memory. Contrary to our expectations, hippocampal volume (assessed in a subsample, n = 592) did not account for significant variance in subjective memory, objective memory or depressive symptoms. Nonetheless, depressive symptoms were related to poorer memory for pictures presented in negative contexts, even after adjusting for memory for pictures in neutral contexts.

Thus the symptoms of depression, associated with subjective memory complaints, appear better assessed by memory performance in affective contexts, rather than standardised memory measures. We discuss the implications of these findings for understanding the impact of depressive symptoms on memory functioning in the general population.

Objective – Delusions and lack of insight have traditionally been viewed as the defining characteristics of insanity and in modern psychiatry continue to be central to the diagnosis of psychosis. Little is known about the mechanisms of delusion formation and much of the research into delusions and lack of insight has been focussed on schizophrenia, in spite of the fact that these symptoms are also prominent in other disorders e.g., affective psychosis. The objective of this paper is to review the literature on existing theories of delusions and insight with reference to the effects of affective disturbance on memory processes. Method – Narrative review supplemented by literature searches using Medline, PsycINFO and EMBASE databases for the period 1980 to present using terms “delusion”, “insight” and “affect”. Results – The role of affect on memory in normal psychology and delusions in psychopathology is being increasingly recognised. We sketch out a theory which gives weight to locating the formation and maintenance of mood congruent and mood incongruent delusional beliefs (and insight into such beliefs) within a model of normal memory processes. Conclusion – We conclude that delusional beliefs may represent false or biased memories of internal or external events modified and strengthened of by affective states. We propose that insight rests on an ability to identify these memories as internally generated or biased. In view of the growing body of knowledge accumulating from the study of memory, emotion and their neuropsychological correlates we would suggest using this as an evidence base for the further neuropsychiatric investigation of delusional beliefs.

Declaration of Interest: none.