The effect of tryptophan on quarrelsomeness, agreeableness, and mood in everyday life

Diet Quality and Mental Health Amongst Acute Inpatient Psychiatric Patients

This is the first study that explored the self-reported dietary habits of acute psychiatric inpatients. We found that 75% of the psychiatric inpatients have an unhealthy diet, which correlates with higher body mass index (BMI) and lower education level. We also found an increased sugar consumption in inpatients with schizophrenia. The link between nutrition and mental health has been explored to a limited extent owing to the cumbersome nature of conducting research that involves specific dietary intervention and follow up. Yet, there is existing literature linking poor diet with impaired mental health and poor recovery from depression, amongst other disorders. Good nutrition can be exemplified with diets like the Mediterranean diet with a focus on certain food groups that provide the nutrients linked to neurotransmitters and a fairly new concept of the gut-brain axis. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression. A randomised controlled trial published in the nutritional neuroscience journal yielded a positive outcome and improvement in the overall well-being of the patients enrolled. We explored the dietary habits of acute inpatients. After gathering a detailed diet history, their food habits were compared to a Mediterranean dietary index to assess their dietary patterns. Additionally, variables such as socio-economic characteristics, physical activity, income, BMI, and educational achievement were taken into consideration, with the intention to understand the effect of these factors on a diet consumed by acute patients and the relationship of the diet with their mental wellbeing. Ultimately, this study aims at an important aspect of preventive mental health, i.e., improved dietary habits (e.g., Mediterranean diet) may contribute to more rapid symptoms resolution and acute stabilization on a short-stay inpatient unit.

The effects of 5-hydroxytryptophan on attention and central serotonin neurochemistry in the rhesus macaque

Psychiatric disorders, particularly depression and anxiety, are often associated with impaired serotonergic function. However, serotonergic interventions yield inconsistent effects on behavioral impairments. To better understand serotonin's role in these pathologies, we investigated the role of serotonin in a behavior frequently impaired in depression and anxiety, attention. In this study, we used a quantitative, repeated, within-subject, design to test how L-5-hydroxytryptophan (5-HTP), the immediate serotonin precursor, modulates central serotoninergic function and attention in macaques. We observed that intramuscular 5-HTP administration increased cisternal cerebrospinal fluid (CSF) 5-HTP and serotonin. In addition, individuals' baseline looking duration, during saline sessions, predicted the direction and magnitude in which 5-HTP modulated attention. We found that 5-HTP decreased looking duration in animals with high baseline attention, but increased looking duration in low baseline attention animals. Furthermore, individual differences in 5-HTP's effects were also reflected in how engaged individuals were in the task and how they allocated attention to salient facial features-the eyes and mouth-of stimulus animals. However, 5-HTP constricted pupil size in all animals, suggesting that the bi-directional effects of 5-HTP cannot be explained by serotonin-mediated changes in autonomic arousal. Critically, high and low baseline attention animals exhibited different baseline CSF concentrations of 5-HTP and serotonin, an index of extracellular functionally active serotonin. Thus, our results suggest that baseline central serotonergic functioning may underlie and predict variation in serotonin's effects on cognitive operation. Our findings may help inform serotonin's role in psychopathology and help clinicians predict how serotonergic interventions will influence pathologies.

Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior

Serotonin regulates a wide variety of brain functions and behaviors. Here, we synthesize previous findings that serotonin regulates executive function, sensory gating, and social behavior and that attention deficit hyperactivity disorder, bipolar disorder, schizophrenia, and impulsive behavior all share in common defects in these functions. It has remained unclear why supplementation with omega-3 fatty acids and vitamin D improve cognitive function and behavior in these brain disorders. Here, we propose mechanisms by which serotonin synthesis, release, and function in the brain are modulated by vitamin D and the 2 marine omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Brain serotonin is synthesized from tryptophan by tryptophan hydroxylase 2, which is transcriptionally activated by vitamin D hormone. Inadequate levels of vitamin D (∼70% of the population) and omega-3 fatty acids are common, suggesting that brain serotonin synthesis is not optimal. We propose mechanisms by which EPA increases serotonin release from presynaptic neurons by reducing E2 series prostaglandins and DHA influences serotonin receptor action by increasing cell membrane fluidity in postsynaptic neurons. We propose a model whereby insufficient levels of vitamin D, EPA, or DHA, in combination with genetic factors and at key periods during development, would lead to dysfunctional serotonin activation and function and may be one underlying mechanism that contributes to neuropsychiatric disorders and depression. This model suggests that optimizing vitamin D and marine omega-3 fatty acid intake may help prevent and modulate the severity of brain dysfunction.

Clinical and physiological correlates of irritability in depression: results from the Netherlands study of depression and anxiety

Objective. Irritable and nonirritable depressed patients differ on demographic and clinical characteristics. We investigated whether this extends to psychological and physiological measures. Method. We compared irritable and nonirritable unipolar depressed patients on symptomatology, personality, and (psycho)physiological measures (cortisol, cholesterol, and heart rate variability). Symptomatology was reassessed after one year, and we also compared depressed patients who were irritable or non-irritable at both time points (Irr++ versus Irr--). Results. Almost half (46%; N = 420) of the sample was classified as irritable. These patients scored higher on depression severity, anxiety, hypomanic symptoms, and psychological variables. No differences were observed on physiological markers after correction for depression severity. The same pattern was found when comparing Irr++ and Irr-- groups. Conclusion. Irritable and non-irritable depressed patients differ on clinical and psychological variables, but not on the currently investigated physiological markers. The clinical relevance of the distinction and the significance of the hypomanic symptoms remain to be demonstrated.