Protein intake is associated with cognitive functioning in individuals with psychiatric disorders

Effect of dietary protein intake on cognitive function in the elderly with chronic kidney disease: analysis of the National Health and Nutrition Examination Survey 2011-2014

BACKGROUND

Cognitive dysfunction is prevalent among the elderly diagnosed with chronic kidney disease (CKD). Low protein diets are used for retarding the progression of CKD in clinical practice. Nonetheless, the impact of dietary protein consumption on cognitive function in this population remains uncertain.

METHODS

We recruited 2306 participants (≥60 years) from 2011 to 2014 National Health and Nutrition Examination Survey (NHANES). 24-h dietary recall questionnaire was utilized to evaluate protein intake. Cognitive function was measured using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). Participants' characteristics were analyzed, and the interaction between protein consumption and CKD on cognitive impairment were analyzed using a logistic regression model.

RESULTS

We divided participants into three groups based on CKD stages: no CKD, CKD stage G1 to G2 (19%), and CKD stage G3 to G5 (18%). The average protein intake was 0.97 g/(kg·d). In the higher protein intake group, CKD stages G1 to G2 elevated the risk of immediate memory impairment (OR: 2.441, 95% Cl: 1.161-5.132 for protein consumption in 1.0-1.2g/(kg·d); OR: 2.225, 95% Cl: 1.015-4.876 for protein consumption in >1.2 g/(kg·d)). However, no similar resuts were observed in the lower protein intake group. In addition, the interaction between CKD status and protein intake on immediate memory was statistically significant (p = .041).

CONCLUSION

A higher probability of cognitive impairment in the elderly with early-stage CKD may be linked to higher protein intake. Low protein diets may be a potential strategy to release cognitive impairment in the elderly with early-stage CKD.

Causal relationships between dietary habits and five major mental disorders: A two-sample Mendelian randomization study

OBJECTIVE

To explore the causal relationship between dietary habits and five major mental disorders using the two-sample Mendelian randomization (MR) analysis.

METHODS

This study was based on the summary data of the genome-wide association study (GWAS) on diet and five major mental disorders in the European population. The genetic locus data of five major mental disorders (mania, bipolar disorder, manic depression, depression, schizophrenia) from those who never eat eggs, dairy, wheat, and sugar were used. Two-sample MR analysis was conducted to evaluate the causal relationship between diet and five major mental disorders.

RESULTS

This study revealed a causal relationship between "Never eat Wheat products" and all five types of mental disorders (mania, bipolar disorder, manic depression, depression, schizophrenia), demonstrating a significant negative correlation (P < 0.05). However, no significant causal relationship was observed between "Never eat Sugar or foods/drinks containing sugar" and any of the five mental disorders (P > 0.05). Furthermore, the study found that the statement "Never eat eggs, dairy, wheat, sugar: I eat all of the above" had a causal relationship with mania, bipolar disorder, and manic depression, showing a significant positive correlation (P < 0.05). However, this statement did not exhibit a significant causal relationship with depression and schizophrenia (P > 0.05).

CONCLUSION

There was a negative correlation between never eating wheat products and the five mental disorders (mania, bipolar disorder, manic depression, depression, schizophrenia), indicating that never eating wheat products may reduce the risk of mental disorders.

Restriction of dietary protein in rats increases progressive-ratio motivation for protein

Low-protein diets can impact food intake and appetite, but it is not known if motivation for food is changed. In the present study, we used an operant behavioral task - the progressive ratio test - to assess whether motivation for different foods was affected when rats were maintained on a protein-restricted diet (REST, 5% protein diet) compared to non-restricted control rats (CON, 18% protein). Rats were tested either with nutritionally-balanced pellets (18.7% protein, Experiment 1) or protein-rich pellets (35% protein, Experiment 2) as reinforcers. Protein restriction increased breakpoint for protein-rich pellets, relative to CON rats, whereas no difference in breakpoint for nutritionally-balanced pellets was observed between groups. When given free access to either nutritionally-balanced pellets or protein-rich pellets, REST and CON rats did not differ in their intake. We also tested whether a previous history of protein restriction might affect present motivation for different types of food by assessing breakpoint of previously REST animals that were subsequently put on standard maintenance chow (protein-repleted rats, REPL, Experiment 2). REPL rats did not show increased breakpoint, relative to their initial encounter with protein-rich pellets while they were protein-restricted. This study demonstrates that restriction of dietary protein induces a selective increased motivation for protein-rich food, a behavior that disappears once rats are not in need of protein.

Nutrition and bipolar disorder: a systematic review

INTRODUCTION

Individuals with bipolar disorder (BD) have higher rates of unhealthy lifestyles and risk for medical comorbidities Research currently suggests that dietary factors may play a role in the development of depression and anxiety. Therefore, nutritional approaches are potential strategies for the treatment of BD. The aim of this review is to summarize the available evidence on nutrition and BD.

MATERIALS AND METHODS

The paper was developed based on PRISMA 2020 guidelines. The search was conducted in Sep-2021 using PubMed and Cochrane Library, augmented by manually checked references lists. The search found 986 studies, of which 47 were included, combined with 13 from reference lists, totaling 60 studies.

RESULTS

There were 33 observational trials, of which 15 focused on fatty acids, 9 on micronutrients, 5 on specific foods, 4 on macro and micronutrients. The 27 interventional studies mainly focused on fatty acids, micronutrients and N-acetylcysteine (NAC).

DISCUSSION

Dietary intake or supplementation of unsaturated fatty acids, mainly Omega-3 seems to be associated with improved BD symptoms, along with seafood, folic acid and zinc. Studies found variable, mainly non-significant impacts of creatine, carnitine, vitamin D, inositol or NAC supplementation on BD. There are promising results associated with Coenzyme Q10 (Coq10) and probiotics. Taken together, these preliminary findings suggest that dietetic approaches might be included as part of BD treatment. Also considering the high risk of metabolic disorders in individuals with BD, they should be encouraged to choose healthy dietary lifestyles, including daily intake of fruits, vegetables, seafood and whole grains.

Management of constipation in patients with schizophrenia—a case study and review of literature

Background

Schizophrenia is a disorder that affects about 1% of the US population, with an extensive impact on patients’ health and their risk of later developing comorbidities from treatment. While literature on the side effect profile of antipsychotics is abundant, there are few studies on identification of anticholinergic effects on gut motility and prophylaxis development. The aim of this review is to consider antipsychotic-associated constipation in patients with schizophrenia and to discuss management of antipsychotic-induced constipation as documented in the literature.

Main body

We present a case of antipsychotic-induced constipation and conducted a literature review assessing the prevalence of this issue in this population. The search was done on Embase, MEDLINE, Cochrane Library, and PubMed databases. Key word searches included constipation with concurrent antipsychotic use, antipsychotics and anticholinergic effects, factors causing constipation in schizophrenia, social disparities involved with constipation, and colorectal cancer screenings.

Main findings included high complication rates that may be explained by clozapine-specific side effects, negative health habits, disease, and treatment-related metabolic disorders. Co-existing negative symptoms could also be associated with health outcomes and was found to have adverse consequences on schizophrenia progression. Comorbidities of diabetes and cardiovascular complications contributed to gut hypomotility. Caregiver burden was a factor in delayed recognition of constipation as a side effect. Routine surveillance for symptoms and optimization of medications facilitates early recognition of constipation.

Conclusion

Overall, there is insufficient trial-based evidence to compare the effectiveness and safety of common pharmacological interventions for constipation, such as lactulose, polyethylene glycol, stool softeners, and lubricant laxatives.

Gut-brain axis: A matter of concern in neuropsychiatric disorders…!

The gut microbiota is composed of a large number of microbes, usually regarded as commensal bacteria. It has become gradually clear that gastrointestinal microbiota affects gut pathophysiology and the central nervous system (CNS) function by modulating the signaling pathways of the microbiota-gut-brain (MGB) axis. This bidirectional MGB axis communication primarily acts through neuroendocrine, neuroimmune, and autonomic nervous systems (ANS) mechanisms. Accumulating evidence reveals that gut microbiota interacts with the host brain, and its modulation may play a critical role in the pathology of neuropsychiatric disorders. Recently, neuroscience research has established the significance of gut microbiota in the development of brain systems that are essential to stress-related behaviors, including depression and anxiety. Application of modulators of the MGB, such as psychobiotics (e.g., probiotics), prebiotics, and specific diets, may be a promising therapeutic approach for neuropsychiatric disorders. The present review article primarily focuses on the relevant features of the disturbances of the MGB axis in the pathophysiology of neuropsychiatric disorders and its potential mechanisms.