Caffeine consumption and schizophrenia: A highlight on adenosine receptor-independent mechanisms

Chronic Caffeine Consumption, Alone or Combined with Agomelatine or Quetiapine, Reduces the Maximum EEG Peak, As Linked to Cortical Neurodegeneration, Ovarian Estrogen Receptor Alpha, and Melatonin Receptor 2

RATIONALE

Evidence of the effects of chronic caffeine (CAFF)-containing beverages, alone or in combination with agomelatine (AGO) or quetiapine (QUET), on electroencephalography (EEG), which is relevant to cognition, epileptogenesis, and ovarian function, remains lacking. Estrogenic, adenosinergic, and melatonergic signaling is possibly linked to the dynamics of these substances.

OBJECTIVES

The brain and ovarian effects of CAFF were compared with those of AGO + CAFF and QUET + CAFF. The implications of estrogenic, adenosinergic, and melatonergic signaling and the brain-ovarian crosstalk were investigated.

METHODS

Adult female rats were administered AGO (10 mg/kg), QUET (10 mg/kg), CAFF, AGO + CAFF, or QUET + CAFF, once daily for 8 weeks. EEG, estrous cycle progression, and microstructure of the brain and ovaries were examined. Brain and ovarian 17β-estradiol (E2), antimullerian hormone (AMH), estrogen receptor alpha (E2Rα), adenosine receptor 2A (A2AR), and melatonin receptor 2 (MT2R) were assessed.

RESULTS

CAFF, alone or combined with AGO or QUET, reduced the maximum EEG peak, which was positively linked to ovarian E2Rα, negatively correlated to cortical neurodegeneration and ovarian MT2R, and associated with cystic ovaries. A large corpus luteum emerged with AGO + CAFF and QUET + CAFF, antagonizing the CAFF-mediated increased ovarian A2AR and reduced cortical E2Rα. AGO + CAFF provoked TTP delay and increased ovarian AMH, while QUET + CAFF slowed source EEG frequency to δ range and increased brain E2.

CONCLUSIONS

CAFF treatment triggered brain and ovarian derangements partially antagonized with concurrent AGO or QUET administration but with no overt affection of estrus cycle progression. Estrogenic, adenosinergic, and melatonergic signaling and brain-ovarian crosstalk may explain these effects.

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.

The association between coffee consumption and risk of incident depression and anxiety: Exploring the benefits of moderate intake

Accumulating evidence has reported the associations of coffee consumption with physical conditions and mortality, but the associations with mental disorders were limited. The objective of this study was to examine the associations of coffee consumption with incident depression and anxiety, and to assess whether the associations differed by coffee subtypes (instant, ground, and decaffeinated coffee) or additives (milk, sugar-sweetened, and artificial-sweetened). In this prospective cohort study, we utilized data from the UK Biobank and included a total of 146,566 participants who completed the touchscreen questionnaire at baseline between 2006 and 2010. During the follow-up, incident depression and anxiety were measured in 2016 using the Patient Health Questionnaire (PHQ)-9 and the Generalised Anxiety Disorder Assessment (GAD)-7, respectively. Multivariable-adjusted logistic regression models and restricted cubic splines were used to assess the associations. Approximately 80.7% of participants reported consuming coffee, and most drank 2 to 3 cups per day (41.2%). We found J-shaped associations between coffee consumption and both incident depression and anxiety, with the lowest risk of the mental disorders occurring at around 2-3 cups per day. Results were similar for participants who drank 2-3 cups of ground coffee, milk-coffee, or unsweetened coffee. Our findings highlight that 2-3 cups of coffee consumption could be recommended as part of a healthy lifestyle to improve mental health.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

Caffeine-Induced Acute and Delayed Responses in Cerebral Metabolism of Control and Schizophrenia-Like Wisket Rats

Recently, morphological impairments have been detected in the brain of a triple-hit rat schizophrenia model (Wisket), and delayed depressive effects of caffeine treatment in both control and Wisket animals have also been shown. The aims of this study were to determine the basal and caffeine-induced acute (30 min) and delayed (24 h) changes in the cerebral ¹⁸fluorodeoxyglucose (¹⁸F-FDG) uptake by positron emission tomography (PET) in control and Wisket rats. No significant differences were identified in the basal whole-brain metabolism between the two groups, and the metabolism was not modified acutely by a single intraperitoneal caffeine (20 mg/kg) injection in either group. However, one day after caffeine administration, significantly enhanced ¹⁸F-FDG uptake was detected in the whole brain and the investigated areas (hippocampus, striatum, thalamus, and hypothalamus) in the control group. Although the Wisket animals showed only moderate enhancements in the ¹⁸F-FDG uptake, significantly lower brain metabolism was observed in this group than in the caffeine-treated control group. This study highlights that the basal brain metabolism of Wisket animals was similar to control rats, and that was not influenced acutely by single caffeine treatment at the whole-brain level. Nevertheless, the distinct delayed responsiveness to this psychostimulant in Wisket model rats suggests impaired control of the cerebral metabolism.

Sugars, Alcohol, and Caffeine Intake From Drinks Among Outpatients With Mental Health Disorders in Greece: A Pilot Study

Background and aim

Excessive intake of sugars and energy from drinks has been postulated to increase the risk of obesity, which may in turn be associated with mental health disorders. In addition, excessive intakes of alcohol and caffeine may co-occur with psychiatric disorders. The purpose of the present pilot study was to estimate energy, sugar, caffeine, and alcohol intakes through the consumption of drinks in patients with schizophrenia and affective disorders and assess potential differences in drink consumption between the two disorders.

Methodology

The current study included 89 outpatients with schizophrenia (n = 36) and affective disorders (n = 53) attending the psychiatric clinic of the University General Hospital of Larissa (UGHL) in Greece. In addition to anthropometric measurements, the patients were asked to complete a specific, previously validated questionnaire on the frequency of drink consumption in order to estimate sugar, caffeine, and alcohol intakes.

Results

The participants had a mean body mass index (BMI) of 28.9 ± 5.6 kg/m2 without significant differences between the two types of mental disorders. Similarly, the mean waist circumference (102.6 ± 15.7 cm) and mean body fat percentage (32.9% ± 10.8%) were above the recommended values. The total energy intake from drinks was more than a third of the estimated daily energy requirements. Although there was no significant difference in the mean daily caffeine intake, those with affective disorders had a significantly higher intake of sugars from drinks (median (Mdn) = 80.0 (interquartile range (IQR) = 89.8) g/day) and alcohol (Mdn = 45.6 (IQR = 31.1) g/day), compared to those with schizophrenia (Mdn = 60.0 (IQR = 45.4) g/day and Mdn = 24.9 (IQR = 19.8) g/day, respectively).

Conclusions

Considering the link between high sugar and alcohol intake with excess body weight and mental health, these preliminary data are of particular concern and point to the need for better dietary counseling in order to improve the dietary behaviors of these patients.