Brain volume abnormalities and neurocognitive deficits in diabetes mellitus: points of pathophysiological commonality with mood disorders?

The effect of Mediterranean diet instructions on depression, anxiety, stress, and anthropometric indices: A randomized, double-blind, controlled clinical trial

Evidence suggests that adopting a healthy diet, such as the Mediterranean Diet (MD), can positively affect mental health. To further explore this, a study was conducted to determine the impact of MD instruction over 12 weeks on depression, anxiety, stress, and anthropometric indices. The study is a randomized, double-blind, controlled clinical trial with sixty participants who reported stress, anxiety, and depression conducted in Tabriz, Iran (2022-2023). They were randomly assigned to either the intervention group (n = 30), which received MD instruction, or the control group (n = 30), which received standard healthy nutrition education. Both groups were asked to follow their respective nutrition education plans for 12 weeks. After 12 weeks, depression, anxiety, and stress levels were measured using the DASS-21 questionnaire, and anthropometric indices were assessed. Initially, the unadjusted DASS-21 scores for depression, anxiety, and stress did not show significant differences between the two groups. However, after adjusting for baseline variables (model 2), all scores decreased significantly (the P-value for all scores was < 0.001). There was no significant difference in weight and BMI between the intervention and control groups. However, after adjusting the results based on baseline values (Model 2) and adherence to the program (Model 3), weight and BMI were significantly reduced in the MD group (P-values for both cases and both models were < 0.001). Overall, despite some significant findings, the results were not noticeable from a clinical perspective. The study provides some indications that following the Mediterranean diet may lead to improvements in weight and mental well-being.

Type-2 Diabetes Alters Hippocampal Neural Oscillations and Disrupts Synchrony between the Hippocampus and Cortex

Type 2 diabetes mellitus (T2DM) increases the risk of neurological diseases, yet how brain oscillations change as age and T2DM interact is not well characterized. To delineate the age and diabetic effect on neurophysiology, we recorded local field potentials with multichannel electrodes spanning the somatosensory cortex and hippocampus (HPC) under urethane anesthesia in diabetic and normoglycemic control mice, at 200 and 400 days of age. We analyzed the signal power of brain oscillations, brain state, sharp wave associate ripples (SPW-Rs), and functional connectivity between the cortex and HPC. We found that while both age and T2DM were correlated with a breakdown in long-range functional connectivity and reduced neurogenesis in the dentate gyrus and subventricular zone, T2DM further slowed brain oscillations and reduced theta-gamma coupling. Age and T2DM also prolonged the duration of SPW-Rs and increased gamma power during SPW-R phase. Our results have identified potential electrophysiological substrates of hippocampal changes associated with T2DM and age. The perturbed brain oscillation features and diminished neurogenesis may underlie T2DM-accelerated cognitive impairment.

Glucagon-like peptide 1 (GLP-1) receptor agonists as a protective factor for incident depression in patients with diabetes mellitus: A systematic review

Glucagon-like peptide 1 (GLP-1) receptor agonists are widely used for glycemic control in patients with diabetes mellitus (DM) and are primarily indicated for type 2 diabetes mellitus (T2DM). GLP-1 receptor agonists have also been shown to have neuroprotective and antidepressant properties. Replicated evidence suggests that individuals with DM are significantly more likely to develop depression. Herein, we aim to investigate whether GLP-1 receptor agonists can be used prophylactically on patients with DM to lower the risk of incident depression. We conducted a systematic search for English-language articles published on the PubMed/MEDLINE, Scopus, Embase, APA, PsycInfo, Ovid and Google Scholar databases from inception to June 6, 2022. Four retrospective observational studies were identified that evaluated the neuroprotective effects of GLP-1 receptor agonists on incident depression in patients with DM. We found mixed results with regards to lowering the risk of incident depression, with two studies demonstrating a significant reduction in risk and two studies showing no such effect. A single study found that dulaglutide may lower susceptibility to depression. Our results were limited by high interstudy heterogeneity, paucity of literature, and lack of controlled trials. While we did not find evidence of GLP-1 receptor agonists significantly lowering risk of incident depression in patients with DM, promising neuroprotective data presented in two of the included papers, specifically on dulaglutide where information is scarce, provide the impetus for further investigation. Future research should focus on better elucidating the neuroprotective potential of different classes and doses of GLP-1 receptor agonists using controlled trials.

Type-2 diabetes alters hippocampal neural oscillations and disrupts synchrony between hippocampus and cortex

Type 2 diabetes mellitus (T2DM) increases the risk of neurological diseases, yet how brain oscillations change as age and T2DM interact is not well characterized. To delineate the age and diabetic effect on neurophysiology, we recorded local field potentials with multichannel electrodes spanning the somatosensory cortex and hippocampus (HPC) under urethane anesthesia in diabetic and normoglycemic control mice, at 200 and 400 days of age. We analyzed the signal power of brain oscillations, brain state, sharp wave associate ripples (SPW-Rs), and functional connectivity between the cortex and HPC. We found that while both age and T2DM were correlated with a breakdown in long-range functional connectivity and reduced neurogenesis in the dentate gyrus and subventricular zone, T2DM further slowed brain oscillations and reduced theta-gamma coupling. Age and T2DM also prolonged the duration of SPW-Rs and increased gamma power during SPW-R phase. Our results have identified potential electrophysiological substrates of hippocampal changes associated with T2DM and age. The perturbed brain oscillation features and diminished neurogenesis may underlie T2DM-accelerated cognitive impairment.

The Burden of Carbohydrates in Health and Disease

Foods high in carbohydrates are an important part of a healthy diet, since they provide the body with glucose to support bodily functions and physical activity. However, the abusive consumption of refined, simple, and low-quality carbohydrates has a direct implication on the physical and mental pathophysiology. Then, carbohydrate consumption is postulated as a crucial factor in the development of the main Western diseases of the 21st century. We conducted this narrative critical review using MedLine (Pubmed), Cochrane (Wiley), Embase, and CinAhl databases with the MeSH-compliant keywords: carbohydrates and evolution, development, phylogenetic, GUT, microbiota, stress, metabolic health, consumption behaviors, metabolic disease, cardiovascular disease, mental disease, anxiety, depression, cancer, chronic kidney failure, allergies, and asthma in order to analyze the impact of carbohydrates on health. Evidence suggests that carbohydrates, especially fiber, are beneficial for the well-being and growth of gut microorganisms and consequently for the host in this symbiotic relationship, producing microbial alterations a negative effect on mental health and different organic systems. In addition, evidence suggests a negative impact of simple carbohydrates and refined carbohydrates on mood categories, including alertness and tiredness, reinforcing a vicious circle. Regarding physical health, sugar intake can affect the development and prognosis of metabolic disease, as an uncontrolled intake of refined carbohydrates puts individuals at risk of developing metabolic syndrome and subsequently developing metabolic disease.

Differences in brain activity between normal and diabetic rats under isoflurane anesthesia: a resting-state functional MRI study

BACKGROUND

Altered neural activity based on the fractional amplitude of low-frequency fluctuations (fALFF) has been reported in patients with diabetes. However, whether fALFF can differentiate healthy controls from diabetic animals under anesthesia remains unclear. The study aimed to elucidate the changes in fALFF in a rat model of diabetes under isoflurane anesthesia.

METHODS

The first group of rats (n = 5) received a single intraperitoneal injection of 70 mg/kg streptozotocin (STZ) to cause the development of diabetes. The second group of rats (n = 7) received a single intraperitoneal injection of the same volume of solvent. Resting-state functional magnetic resonance imaging was used to assess brain activity at 4 weeks after STZ or solvent administration.

RESULTS

Compared to the healthy control animals, rats with diabetes showed significantly decreased fALFF in various brain regions, including the cingulate cortex, somatosensory cortex, insula, and striatum (all P < 0.05). The decreased fALFF suggests the aberrant neural activities in the diabetic rats. No regions were detected in which the control group had a lower fALFF than that in the diabetes group.

CONCLUSIONS

The results of this study demonstrated that the fALFF could be used to differentiate healthy controls from diabetic animals, providing meaningful information regarding the neurological pathophysiology of diabetes in animal models.

Cognitive function in diabetic persons with peripheral neuropathy: a systematic review and meta-analysis

OBJECTIVES

The aim of this study is to improve our knowledge of cognitive function in individuals with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus and with peripheral diabetic neuropathy (DPN).

METHODS

A systematic review and meta-analysis was performed of publications included in PubMed, Scopus, PsycInfo and Web of Science databases until November 2021. The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) with reference number: CRD42021229163.

RESULTS

A total of 832 articles were identified, 19 of which were selected. The presence of DPN was associated with global cognitive impairment in the T1DM persons in two studies (p=0.046; p=0.03) and T2DM persons in four (p<0.001; p<0.02; p=0.011; p=<0.05). Differences in specific dimensions - memory, attention, and psychomotor speed - were found in both kinds of diabetes. The meta-analysis showed that the individuals with T2DM and DPN presented a lower mean cognitive performance than those without DPN (-1.0448; 95% CI: -1.93%; -0.16%). Depression was associated with impaired cognitive function in these diabetic persons (p<0.01).

CONCLUSION

The review reveals the great variability in instruments and methodologies, while providing results that support the presence of both global and domain-specific cognitive impairment in diabetic persons with DPN.

Association of type 1 diabetes and educational achievement in 16-20-year-olds: A Danish nationwide register study

AIMS

The objective of the study was to compare grade point averages (GPAs) on compulsory school exit exams (exam GPA) and educational attainment at age 16 and 20 for individuals with and without type 1 diabetes.

METHODS

This study was a population-based retrospective cohort study, which included the 1991 to 1998 birth cohorts in Denmark. Follow-up was conducted at age 16 and 20 (follow-up period; 1 January, 2007 to 31 December, 2018). There were 2083 individuals with and 555,929 individuals without type 1 diabetes. Linear regression and generalized linear models compared outcomes with and without adjustments for socio-economic characteristics.

RESULTS

A total of 558,012 individuals (51% males) were followed to the age of 20. Having type 1 diabetes was associated with a lower exam GPA when adjusting for socio-economic status (difference: -0.05 (95% CI, -0.09 to -0.01), a higher relative risk of not completing compulsory school by age 16 (1.37, 95% CI, 1.22 to 1.53)), and a higher relative risk of not completing or being enrolled in upper secondary education by age 20 (1.05, 95% CI, 1.00 to 1.10). Haemoglobin A1c (HbA1c) <58 mmol/mol (7.5%), >7 BGM/day and insulin pump use were associated with better educational achievement.

CONCLUSION

Type 1 diabetes was associated with a marginally lower exam GPA and a higher risk of not completing compulsory school by age 16 and lower educational attainment by age 20. The findings were modified by HbA1c, BGM and insulin pump use.

Hippocampal-specific insulin resistance elicits behavioral despair and hippocampal dendritic atrophy

Insulin resistance is a major contributor to the neuroplasticity deficits observed in patients with metabolic disorders. However, the relative contribution of peripheral versus central insulin resistance in the development of neuroplasticity deficits remains equivocal. To distinguish between peripheral and central insulin resistance, we developed a lentiviral vector containing an antisense sequence selective for the insulin receptor (LV-IRAS). We previously demonstrated that intra-hippocampal injection of this vector impairs synaptic transmission and hippocampal-dependent learning and memory in the absence of peripheral insulin resistance. In view of the increased risk for the development of neuropsychiatric disorders in patients with insulin resistance, the current study examined depressive and anxiety-like behaviors, as well as hippocampal structural plasticity in rats with hippocampal-specific insulin resistance. Following hippocampal administration of either the LV-control virus or the LV-IRAS, anhedonia was evaluated by the sucrose preference test, despair behavior was assessed in the forced swim test, and anxiety-like behaviors were determined in the elevated plus maze. Hippocampal neuron morphology was studied by Golgi-Cox staining. Rats with hippocampal insulin resistance exhibited anxiety-like behaviors and behavioral despair without differences in anhedonia, suggesting that some but not all components of depressive-like behaviors were affected. Morphologically, hippocampal-specific insulin resistance elicited atrophy of the basal dendrites of CA3 pyramidal neurons and dentate gyrus granule neurons, and also reduced the expression of immature dentate gyrus granule neurons. In conclusion, hippocampal-specific insulin resistance elicits structural deficits that are accompanied by behavioral despair and anxiety-like behaviors, identifying hippocampal insulin resistance as a key factor in depressive illness.

Two weeks of moderate intensity locomotor training increased corticosterone concentrations but did not alter the number of adropin-immunoreactive cells in the hippocampus of diabetic type 2 and control rats

Adropin (ADR) plays a role in metabolism regulation and its alterations in obesity and diabetes have been found. Treatment with ADR was beneficial in metabolic diseases, and physical exercise increased ADR concentrations in obese patients. However, data on the distribution of ADR in the brain are sparse. The role of metabolic status and physical exercise on its expression in the brain is undiscovered. We hypothesized that diabetes type 2 (DM2) and/or exercise will alter number of ADR-immunoractive (-ir) cells in the rat brain. Animals were divided into groups: diabetes type 2 (receiving high-fat diet and injections of streptozotocin) and control (fed laboratory chow diet; C). Rats were further divided into: running group (2 weeks of forced exercise on a treadmill) and non-running group. Body mass, metabolic and hormonal profiles were assessed. Immunohistochemistry was run to study ADR-ir cells in the brain. We found that: 1) in DM2 animals, running decreased insulin and increased glucose concentrations; 2) in C rats, running decreased insulin concentrations and had no effect on glucose concentration in blood; 3) running increased corticosterone (CORT) concentrations in DM2 and C rats; 4) ADR-ir cells were detected in the hippocampus and ADR-ir fibers in the arcuate nucleus of the hypothalamus, which is a novel location; 5) metabolic status and running, however, did not change number of these cells. We concluded that 2 weeks of forced moderate intensity locomotor training induced stress response present as increased concentration of CORT and did not influence number of ADR-ir cells in the brain.

Meta-analysis of cognitive and behavioral tests in leptin- and leptin receptor-deficient mice

Leptin is a hormone produced by adipocytes that regulates food intake and metabolism. Leptin-related gene-deficient mice, such as db/db and ob/ob mice, are widely used to study diabetes and its related diseases. However, broad effects of leptin appear to cause variability in behavioral test results. We performed a meta-analysis of major behavioral tests in db/db and ob/ob mice. These mice exhibited significant impairments in the Morris water maze, forced swim, novel object recognition, Y-maze, tail suspension, and light-dark box tests, whereas the elevated plus maze and open field tests did not reveal significant changes. We also performed correlation and regression analyses between the animals' performances and the experimental protocols and conditions. The memory-related tests were characterized by the correlations of their results with animal age, while the performances in the elevated plus-maze and forced swim tests were affected by the width of the devices used. In conclusion, db/db and ob/ob mice mainly exhibit memory deficits and depression-like behavior, although experimenters should be aware of animal age and device size in conducting experiments.

Association of impaired fasting glucose and Type 2 Diabetes Mellitus with brain volume changes in Alzheimer's Disease patients analyzed by MRI: a retrospective study

Objectives

Alzheimer’s disease (AD), impaired fasting glucose (IFG), and Type 2 diabetes mellitus (T2DM) were reported associated with smaller brain volumes. Nevertheless, the association of hyperglycemia with brain volume changes in AD patients remains unclear. To investigate this issue, structural magnetic resonance imaging was used to compare brain volumes among AD patients with different fasting glucose levels.

Methods

Eighty-five AD patients were divided into three groups based on their fasting glucose level as suggested by the American Diabetes Association: normal fasting glucose group (AD_NFG, n = 45), AD_IFG group (n = 15), and AD_T2DM group (n = 25). Sagittal 3D T1-weighted images were obtained to calculate the brain volume. Brain parenchyma and 33 brain structures were automatically segmented. Each regional volume was analyzed among groups. For regions with statistical significance, partial correlation analysis was used to evaluate their relationships with fasting glucose level, corrected for Mini-Mental State Examination score, age, education level, cholesterol, triglyceride, and blood pressure.

Results

Compared with the AD_IFG and AD_NFG groups, the volume of pons in AD_T2DM group was significantly smaller. Fasting glucose was negatively correlated with pontine volume.

Conclusions

T2DM may exacerbate pontine atrophy in AD patients, and fasting glucose level is associated with pontine volume.

Food and mood: how do diet and nutrition affect mental wellbeing?

Poor nutrition may be a causal factor in the experience of low mood, and improving diet may help to protect not only the physical health but also the mental health of the population, say Joseph Firth and colleagues

The effect of overweight/obesity on cognitive function in euthymic individuals with bipolar disorder

Background

Persistent impairment in cognitive function has been described in euthymic individuals with bipolar disorder. Collective work indicates that obesity is associated with reduced cognitive function in otherwise healthy individuals. This sub-group post-hoc analysis preliminarily explores and examines the association between overweight/obesity and cognitive function in euthymic individuals with bipolar disorder.

Methods

Euthymic adults with DSM-IV-TR-defined bipolar I or II disorder were enrolled. Subjects included in this post-hoc analysis (n = 67) were divided into two groups (normal weight, body mass index [BMI] of 18.5–24.9kg/m2; overweight/obese, BMI≥25.0kg/m2). Demographic and clinical information were obtained at screening. At baseline, study participants completed a comprehensive cognitive battery to assess premorbid IQ, verbal learning and memory, attention and psychomotor processing speed, executive function, general intellectual abilities, recollection and habit memory, as well as self-perceptions of cognitive failures.

Results

BMI was negatively correlated with attention and psychomotor processing speed as measured by the Digit Symbol Substitution Test (P<0.01). Overweight and obese bipolar individuals had a significantly lower score on the Verbal Fluency Test when compared to normal weight subjects (P<0.05). For all other measures of cognitive function, non-significant trends suggesting a negative association with BMI were observed, with the exception of measures of executive function (i.e. Trail Making Test B) and recollection memory (i.e. process-dissociation task).

Conclusion

Notwithstanding the post-hoc methodology and relatively small sample size, the results of this study suggest a possible negative effect of overweight/obesity on cognitive function in euthymic individuals with bipolar disorder. Taken together, these data provide the impetus for more rigorous evaluation of the mediational role of overweight/obesity (and other medical co-morbidity) on cognitive function in psychiatric populations.

The cognitive and psychological effects of living with type 1 diabetes: a narrative review

Across the lifespan, type 1 diabetes mellitus has a profound (neuro)psychological impact. In young people, type 1 diabetes can interfere with psychosocial development and hamper school performance. In adulthood, it can interfere with work life, relationships and parenting. A substantial minority of adults with type 1 diabetes experience coping difficulties and high diabetes-related distress. In youth and adulthood, type 1 diabetes is related to mild cognitive decrements as well as affective disorders, such as depression and anxiety. There is limited literature available that explores the interaction between cognitive and psychological comorbidity and underlying mechanisms. The aims of the present narrative review were to summarize the current state of the literature regarding both cognitive and psychological comorbidities in type 1 diabetes across the lifespan, and to explore potential links between the two domains of interest to make suggestions for future research and clinical practice.

Legume and nut consumption in relation to depression, anxiety and psychological distress in Iranian adults

PURPOSE

Although considerable research has been devoted to the link between consumption of legume and nuts and metabolic abnormalities, few studies have examined legume and nut consumption in relation to psychological disorders. The current study aimed to examine the association of legume and nut consumption with depression, anxiety and psychological distress in Iranian adults.

METHODS

This cross-sectional study was carried out among 3172 adult participants aged 18-55 years. Assessment of legume and nut consumption was conducted using a validated dish-based 106-item semi-quantitative food frequency questionnaire. The Iranian validated version of Hospital Anxiety and Depression Scale (HADS) was used to examine psychological health. Scores of 8 or more on either subscale in the questionnaire were considered to indicate the presence of depression or anxiety. Data on psychological distress were collected using the General Health Questionnaire (GHQ), in which the score of 4 or more was considered as having psychological distress.

RESULTS

The mean age of participants was 36.5 ± 7.9 years. In the fully adjusted model, men in the top quintile of legume and nut consumption were 66% less likely to be anxious than those in the bottom quintile (OR 0.34; 95% CI 0.14-0.82). However, such significant relationship was not observed among women (OR 1.06; 95% CI 0.63-1.77). We failed to find any other significant association between legume and nut consumption and depression or psychological distress after adjustment for potential confounders either in men or women.

CONCLUSIONS

We found that consumption of legume and nuts was associated with lower odds of anxiety in men, but not in women. No other significant association was seen among participants. Legume and nut consumption might be promising and, along with medications, could be used to prevent, control or delay psychological disorders.

Association between dietary insulin index and load and psychological disorders

The present study was carried out to determine whether the dietary insulin index (DII) and dietary insulin load (DIL) are related to psychological disorders in a cross-sectional study among adults. A total of 3172 Iranian adults (age range of 18–55 years) were included. Data on dietary intakes were collected using a validated dish-based 106-item semi-quantitative FFQ. DII and DIL were calculated using food insulin index values published earlier. To assess depression and anxiety, an Iranian validated version of the Hospital Anxiety and Depression Scale was used. Furthermore, psychological distress was examined using the General Health Questionnaire. Among women, a significant positive association was seen; such that women in the highest quartile of DIL had higher odds of depression than those in the lowest quartile (OR 1·84; 95 % CI 1·14, 2·96). In terms of DII, in the fully adjusted model, women in the top quartile of DII were more likely to be depressed compared with those in the bottom quartile (OR 1·65; 95 % CI 1·05, 2·58). In conclusion, we found a significant positive association between DIL and DII and odds of depression among women, but not in men. However, such findings were not seen for anxiety and psychological distress.

Adherence to Mediterranean dietary pattern is inversely associated with depression, anxiety and psychological distress

Background: Few studies have assessed adherence to the Mediterranean diet in relation to psychological health, in particular in the Middle East.Objective: To examine the association between adherence to Mediterranean dietary pattern and prevalence of psychological disorders among a large population of Iranian adults.Design: In this cross-sectional study on 3172 Iranian adults aged 18-55 years, we used a validated food frequency questionnaire for the assessment of dietary intakes. Adherence to the Mediterranean dietary pattern was examined using the Trichopoulou et al. method. To assess psychological health, the Iranian validated version of the Hospital Anxiety and Depression Scale (HADS) was used. Psychological distress was assessed through the use of General Health Questionnaire (GHQ).Results: Mean age of study participants was 36.54 ± 4.97 years. After controlling for potential confounders, participants with the greatest adherence to the Mediterranean diet had lower odds for depression (OR: 0.60, 95% CI: 0.46-0.78), anxiety (OR: 0.61, 95% CI: 0.42-0.86) and psychological distress (OR: 0.60, 95% CI: 0.45-0.79) compared with those with the lowest adherence. When the association with components of Mediterranean diet was examined, we found that high intake of fruits and vegetables was associated with a lower odds of depression, anxiety and psychological distress. In contrast, high intake of grains was positively associated with depression, anxiety and psychological distress.Conclusion: We found evidence indicating an inverse association between adherence to Mediterranean dietary pattern and odds of psychological disorders including depression, anxiety and psychological distress.

The effect of type 1 diabetes on the developing brain

The effect of type 1 diabetes on the developing brain is a topic of primary research interest. A variety of potential dysglycaemic insults to the brain can cause cellular and structural injury and lead to altered neuropsychological outcomes. These outcomes might be subtle in terms of cognition but appear to persist into adult life. Age and circumstance at diagnosis appear to play a substantial role in potential CNS injury. A history of diabetic ketoacidosis and chronic hyperglycaemia appear to be more injurious than previously suspected, whereas a history of severe hypoglycaemia is perhaps less injurious. Neurocognitive deficits manifest across multiple cognitive domains, including executive function and speed of information processing. Some evidence suggests that subtle brain injury might directly contribute to psychological and mental health outcomes. Impaired executive function and mental health, in turn, could affect patients' adherence and the ability to make adaptive lifestyle choices. Impaired executive functioning creates a potential feedback loop of diabetic dysglycaemia leading to brain injury, further impaired executive function and mental health, which results in suboptimal adherence, and further dysglycaemia. Clinicians dealing with patients with suboptimal glycaemic outcomes should be aware of these potential issues.

Brain and behavioral correlates of insulin resistance in youth with depression and obesity

Depression, together with insulin resistance, is increasingly prevalent among youth. These conditions have traditionally been compartmentalized, but recent evidence suggests that a shared brain motivational network underlies their co-occurrence. We posit that, in the context of depressive symptoms, insulin resistance is associated with aberrant structure and functional connectivity in the Anterior Cingulate Cortex (ACC) and hippocampus. This motivational neural circuit underlies dysfunctional behavioral responses and increased sensitivity to rewarding aspects of ingesting high calorie food that lead to disinhibition of eating even when satiated. To investigate this shared mechanism, we evaluated a sample of forty-two depressed and overweight (BMI > 85th%) youth aged 9 to 17. Using ACC and hippocampus structural and seed-based regions of interest, we investigated associations between insulin resistance, depression, structure (ACC thickness, and ACC and hippocampal area), and resting-state functional connectivity (RSFC). We predicted that aberrant associations among these neural and behavioral characteristics would be stronger in insulin resistant compared to insulin sensitive youth. We found that youth with greater insulin resistance had higher levels of anhedonia and more food seeking behaviors, reduced hippocampal and ACC volumes, and greater levels of ACC and hippocampal dysconnectivity to fronto-limbic reward networks at rest. For youth with high levels of insulin resistance, thinner ACC and smaller hippocampal volumes were associated with more severe depressive symptoms, whereas the opposite was true for youth with low levels of insulin resistance. The ACC-hippocampal motivational network that subserves depression and insulin resistance separately, may represent a critical neural interaction that link these syndromes together.

Physical performance and cognitive functioning among individuals with diabetes: Findings from the China Health and Retirement Longitudinal Study Baseline Survey

AIMS

The purpose of this study was to examine individual associations of each physical performance measure with domains of cognitive functioning and to determine best physical performance measures strongly associated with each domain of cognitive functioning among middle-aged and older adults with diabetes.

BACKGROUND

Tests of physical performance are strongly correlated with cognitive decline in general elderly population. However, far less is known about individual associations of each individual physical performance measure with domains of cognitive functioning among individuals with diabetes.

DESIGN

The study employed a retrospective, cross-sectional design.

METHODS

Baseline data from a national baseline survey collected from May 2011-March 2012 were used. A total of 17,314 individuals aged ≥45 years completed the baseline survey. Diabetes was confirmed for 1,905 participants and these individuals were included in this study.

RESULTS

When grip strength, walking speed, repeated chair stands and standing balance test were added in the regression models, walking speed was the only variable that was significantly associated with figure drawing and grip strength was the only variable that was significantly associated with episodic memory, orientation/attention and overall cognitive score.

CONCLUSION

Since grip strength was the most important factor associated with several domains of cognitive functioning, strategies that improve grip strength in patients with diabetes are prudent. Early interventions to increase levels of physical activity may be important to improve both grip strength and cognitive functioning in this growing population with diabetes.

Hippocampal brain-derived neurotrophic factor determines recruitment of anatomically connected networks after stress in diabetic mice

Diabetes increases adrenal steroids in humans and animal models, but potential interactions with psychological stress remain poorly understood. Diabetic rodents exhibit anxiety and reductions in hippocampal brain-derived neurotrophic factor (BDNF) expression, and these studies investigated whether loss of BDNF-driven hippocampal activity promotes anxiety and disinhibits the HPA axis. Mice with genetic obesity and diabetes (db/db) received intrahippocampal injections of lentivirus for BDNF overexpression (db/db-BDNFOE), and Wt mice received lentiviral constructs for BDNF knockdown (Wt-BDNFKD). Behavioral anxiety and glucocorticoid responses to acute restraint were compared with mice that received a fluorescent reporter (Wt-GFP, db/db-GFP). These experiments revealed that changes in hippocampal BDNF were necessary and sufficient for behavioral anxiety and HPA axis disinhibition. To examine patterns of stress-induced regional activity, we used algorithmic detection of cFos and automated segmentation of forebrain regions to generate maps of functional covariance, which were subsequently aligned with anatomical connectivity weights from the Brain Architecture Management database. db/db-GFP mice exhibited reduced activation of the hippocampal ventral subiculum (vSub) and anterior bed nucleus of stria terminalis (aBNST), and increases in the paraventricular hypothalamus (PVH), relative to Wt-GFP. BDNFKD recapitulated this pattern in Wt mice, and BDNFOE normalized activation of the vSub > aBNST > PVH pathway in db/db mice. Analysis of forebrain activation revealed largely overlapping patterns of network disruption in db/db-GFP and Wt-BDNFKD mice, implicating BDNF-driven hippocampal activity as a determinant of stress vulnerability in both the intact and diabetic brain.

Insulin resistance is associated with smaller brain volumes in a preliminary study of depressed and obese children

OBJECTIVE

During childhood, the brain can consume up to 65% of total calories, and a steady supply of the brain's main fuel glucose needs to be maintained. Although the brain itself is not dependent on insulin for the uptake of glucose, insulin plays an important role in energy homeostasis. Thus, the risk for insulin resistance during brain development may negatively impact the whole brain volume.

METHODS

We investigated the link between the insulin resistance and the whole brain volume as measured by structural Magnetic resonance imaging (MRI) in 46 unmedicated depressed and overweight youths between the ages of 9 and 17 years.

RESULTS

Smaller whole brain volumes were associated with insulin resistance independent of age, sex, depression severity, body mass index, socioeconomic status, Tanner Stage, and Intelligence quotient (IQ) (r = 0.395, P = .014)

CONCLUSIONS

There may be a significant cost for developing insulin resistance on the developing brain. Disentangling the precise relationship between the insulin resistance and the developing brain is critical.

Prefronto-temporal white matter microstructural alterations 20 years after the diagnosis of type 1 diabetes mellitus

OBJECTIVE

Microvascular pathophysiology that uniquely manifests as white matter (WM) abnormalities is often implicated in type 1 diabetes mellitus (T1DM)-related central nervous system (CNS) complications. This study sought to identify regional WM abnormalities in young adults diagnosed with T1DM and further examine their association with cognitive and emotional dysfunction.

RESEARCH DESIGN AND METHODS

Diffusion tensor images (DTI) obtained from 34 young adults with T1DM for ≥15 years (mean duration, 20.9 years), and 16 age- and sex-matched healthy control subjects were analyzed using tract-based spatial statistics. Fractional anisotropy (FA) values of the whole brain were analyzed, and their associations with memory function and depressive symptoms were assessed.

RESULTS

Whole brain voxel-wise analyses showed that T1DM-related FA reductions were most prominent within the fronto-temporo-parietal regions of the brain. Reduced FA values in the bilateral superior longitudinal fasciculi, at which group differences were most prominent, correlated with lower working memory performance in young adults with T1DM (left, P < .001; right, P = .009). Subsyndromal depressive symptoms were also associated with lower FA values in the right inferior fronto-occipital fasciculus (P = .004).

CONCLUSION

Widespread WM microstructural abnormalities in the fronto-temporo-parietal brain regions, which are associated with emotional and cognitive dysfunction, may be a contributing factor to the neural mechanisms underlying T1DM-related CNS complications, thus affecting the quality of life in young adults with T1DM.

Redefining neuroendocrinology: Epigenetics of brain-body communication over the life course

The brain is the central organ of stress and adaptation to stress that perceives and determines what is threatening, as well as the behavioral and physiological responses to the stressor, and it does so somewhat differently in males and females. The expression of steroid hormone receptors throughout the brain has broadened the definition of 'neuroendocrinology' to include the reciprocal communication between the entire brain and body via hormonal and neural pathways. Mediated in part via systemic hormonal influences, the adult and developing brain possess remarkable structural and functional plasticity in response to stress, including neuronal replacement, dendritic remodeling, and synapse turnover. This article is both an account of an emerging field elucidating brain-body interactions at multiple levels, from molecules to social organization, as well as a personal account of my laboratory's role and, most importantly, the roles of trainees and colleagues, along with my involvement in interdisciplinary groups working on this topic.

Canadian Network for Mood and Anxiety Treatments (CANMAT) and International Society for Bipolar Disorders (ISBD) 2018 guidelines for the management of patients with bipolar disorder

The Canadian Network for Mood and Anxiety Treatments (CANMAT) previously published treatment guidelines for bipolar disorder in 2005, along with international commentaries and subsequent updates in 2007, 2009, and 2013. The last two updates were published in collaboration with the International Society for Bipolar Disorders (ISBD). These 2018 CANMAT and ISBD Bipolar Treatment Guidelines represent the significant advances in the field since the last full edition was published in 2005, including updates to diagnosis and management as well as new research into pharmacological and psychological treatments. These advances have been translated into clear and easy to use recommendations for first, second, and third- line treatments, with consideration given to levels of evidence for efficacy, clinical support based on experience, and consensus ratings of safety, tolerability, and treatment-emergent switch risk. New to these guidelines, hierarchical rankings were created for first and second- line treatments recommended for acute mania, acute depression, and maintenance treatment in bipolar I disorder. Created by considering the impact of each treatment across all phases of illness, this hierarchy will further assist clinicians in making evidence-based treatment decisions. Lithium, quetiapine, divalproex, asenapine, aripiprazole, paliperidone, risperidone, and cariprazine alone or in combination are recommended as first-line treatments for acute mania. First-line options for bipolar I depression include quetiapine, lurasidone plus lithium or divalproex, lithium, lamotrigine, lurasidone, or adjunctive lamotrigine. While medications that have been shown to be effective for the acute phase should generally be continued for the maintenance phase in bipolar I disorder, there are some exceptions (such as with antidepressants); and available data suggest that lithium, quetiapine, divalproex, lamotrigine, asenapine, and aripiprazole monotherapy or combination treatments should be considered first-line for those initiating or switching treatment during the maintenance phase. In addition to addressing issues in bipolar I disorder, these guidelines also provide an overview of, and recommendations for, clinical management of bipolar II disorder, as well as advice on specific populations, such as women at various stages of the reproductive cycle, children and adolescents, and older adults. There are also discussions on the impact of specific psychiatric and medical comorbidities such as substance use, anxiety, and metabolic disorders. Finally, an overview of issues related to safety and monitoring is provided. The CANMAT and ISBD groups hope that these guidelines become a valuable tool for practitioners across the globe.

The association of whole and refined grains consumption with psychological disorders among Iranian adults

PURPOSE

Although several studies have examined the link between different types of carbohydrate consumption and depression and anxiety, limited data are available linking whole and refined grains consumption to psychological disorders. We aimed to investigate the association of whole and refined grains consumption with psychological disorders among Iranian adults.

METHODS

A total of 3172 adult people with age range of 18-55 years were included in this cross-sectional study. Data on grains consumption were collected using a validated dish-based 106-item semi-quantitative food frequency questionnaire. To assess depression and anxiety, Iranian validated version of Hospital Anxiety and Depression Scale (HADS) was applied. Furthermore, psychological distress was examined using General Health Questionnaire (GHQ). Psychological disorders were defined based on standard criteria.

RESULTS

Mean age of participants was 36.5 ± 7.9 years. Women in the third quartile of whole grains consumption had lower odds for having anxiety (OR 0.62, 95% CI 0.45-0.85) compared with those in the first quartile. This relationship was also seen even after controlling for potential confounders (OR 0.65, 95% CI 0.44-0.96). In contrast, compared with the first quartile, women in the highest quartile of refined grains consumption had greater odds to have depression (OR 1.76, 95% CI 1.00-3.09) and anxiety (OR 2.03, 95% CI 1.00-4.10) after adjusting for covariates. Such relationships were not observed among men.

CONCLUSION

Moderate consumption of whole grain foods was inversely associated with anxiety in women, but not in men. Furthermore, we found a significant positive association between refined grains consumption, depression and anxiety in women.

Association between carbohydrate nutrition and prevalence of depressive symptoms in older adults

We aimed to examine the relationship between dietary glycaemic index (GI) and glycaemic load of foods consumed, intakes of carbohydrates, sugars and fibre, and the prevalence of depressive symptoms in older adults. Data collected from 2334 participants aged 55+ years and 1952 participants aged 60+ years were analysed. Dietary information was collected using a semi-quantitative FFQ. Depressive symptoms were based on antidepressant use or either the 36-Item Short-Form Survey, which included the Mental Health Index (MHI), or the Center for Epidemiologic Studies Depression-10 Scale. Participants in the highest v. lowest tertile of dietary GI intake had increased odds of depressive symptoms (assessed by the MHI scale), multivariable-adjusted OR 1·55 (95 % CI 1·12, 2·14). Participants in the highest compared with lowest tertile of fruit consumption had reduced odds of prevalent depressive symptoms, multivariable-adjusted OR 0·66 (95 % CI 0·46, 0·95). Total fibre, vegetable fibre and breads/cereal fibre intakes were all inversely associated with the prevalence of depressive symptoms, with global P values of 0·03, 0·01 and 0·03, respectively. Participants in the second v. first tertile of vegetable consumption had 41 % reduced odds of prevalent depressive symptoms, multivariable-adjusted OR 0·59 (95 % CI 0·40, 0·88). We show that dietary GI and fibre intakes as well as consumption of fruits and vegetables are associated with the prevalence of depressive symptoms.

Abdominal obesity is associated with impaired cognitive function in euthymic bipolar individuals

OBJECTIVES

Overweight/obesity has been implicated to play a role in cognitive deficits in bipolar disorder (BD). This study aims to identify the relationship between body fat distribution and different domains of cognition in BD during euthymia.

METHODS

A sample of 100 euthymic individuals with BD was measured with a cognitive test battery (i.e., Trail Making Test-A-B/TM-A/B, d2 Test of Attention, Stroop test, California Verbal Learning Test/CVLT) and an anthropometric measures set (body mass index, waist circumference, hip circumference, waist-to-hip-ratio, waist-to-height-ratio, and lipometry). Patient data were compared with a healthy control group (n = 64).

RESULTS

Results show that overweight patients with BD exhibit lower performance in the TMT-A/B as well as in the free recall performance of the CVLT compared to normal-weight patients with BD and controls. In bipolar individuals, (abdominal) obesity was significantly associated with a poor cognitive performance. In bipolar females, associations with measures of verbal learning and memory were found; in bipolar males, associations with poor performance in the TMT-A/B and in the Stroop interference task were demonstrated. In controls, no associations were found.

CONCLUSIONS

There are several possible pathways moderating the association between obesity and cognition in BD. Anthropometric and lipometry data underline the substantial mediating impact of body fat distribution on cognition in BD.

Epigenetics and energetics in ventral hippocampus mediate rapid antidepressant action: Implications for treatment resistance

Although regulation of energy metabolism has been linked with multiple disorders, its role in depression and responsiveness to antidepressants is less known. We found that an epigenetic and energetic agent, acetyl-l-carnitine (LAC, oral administration), rapidly rescued the depressive- and central and systemic metabolic-like phenotype of LAC-deficient Flinders Sensitive Line rats (FSL). After acute stress during LAC treatment, a subset of FSL continued to respond to LAC (rFSL), whereas the other subset did not (nrFSL). RNA sequencing of the ventral dentate gyrus, a mood-regulatory region, identified metabolic factors as key markers predisposing to depression (insulin receptors Insr, glucose transporters Glut-4 and Glut-12, and the regulator of appetite Cartpt) and to LAC responsiveness (leptin receptors Lepr, metabotropic glutamate receptors-2 mGlu2, neuropeptide-Y NPY, and mineralocorticoid receptors MR). Furthermore, we found that stress-induced treatment resistance in nrFSL shows a new gene profile, including the metabolic regulator factors elongation of long chain fatty acids 7 (Elovl7) and cytochrome B5 reductase 2 (Cyb5r2) and the synaptic regulator NPAS4. Finally, while improving central energy regulation and exerting rapid antidepressant-like effects, LAC corrected a systemic hyperinsulinemia and hyperglicemia in rFSL and failed to do that in nrFSL. These findings establish CNS energy regulation as a factor to be considered for the development of better therapeutics. Agents such as LAC that regulate metabolic factors and reduce glutamate overflow could rapidly ameliorate depression and could also be considered for treatment of insulin resistance in depressed subjects. The approach here serves as a model for identifying markers and underlying mechanisms of predisposition to diseases and treatment responsiveness that may be useful in translation to human behavior and psychopathology.

Deconstructing Diabetes and Depression: Clinical Context, Treatment Strategies, and New Directions

Depression and diabetes are common, chronic, and frequently comorbid diseases that contribute substantially to global disability and mortality. Their relationship is bidirectional: depression increases the risk of developing type 2 diabetes mellitus (T2DM), and diabetes increases the risk of depression. Unhealthy lifestyles and poor self-care by patients with depression contribute to the increased T2DM risk. The psychosocial burden of a diabetes diagnosis and its eventual complications predispose diabetic patients to depressive symptoms. Neuroendocrine alterations and inflammation may underlie the increased risk of T2DM in depression but are also proposed as common causative factors for both illnesses. Screening for depression is essential in T2DM, and vice versa. Selective serotonin reuptake inhibitors effectively treat depression of patients with diabetes and positively influence glycemic control. Psychological interventions are effective for depressive symptoms, but their effect on glycemic control varies. Novel depression interventions targeting inflammation or insulin resistance underscore the common biological underpinnings of mood and metabolism.

Cognitive Deficits as a Mediator of Poor Occupational Function in Remitted Major Depressive Disorder Patients

Cognitive deficits in major depressive disorder (MDD) patients have been described in numerous studies. However, few reports have aimed to describe cognitive deficits in the remitted state of MDD and the mediational effect of cognitive deficits on occupational outcome. The aim of the current review is to synthesize the literature on the mediating and moderating effects of specific domains of cognition on occupational impairment among people with remitted MDD. In addition, predictors of cognitive deficits found to be vocationally important will be examined. Upon examination of the extant literature, attention, executive function and verbal memory are areas of consistent impairment in remitted MDD patients. Cognitive domains shown to have considerable impact on vocational functioning include deficits in memory, attention, learning and executive function. Factors that adversely affect cognitive function related to occupational accommodation include higher age, late age at onset, residual depressive symptoms, history of melancholic/psychotic depression, and physical/psychiatric comorbidity, whereas higher levels of education showed a protective effect against cognitive deficit. Cognitive deficits are a principal mediator of occupational impairment in remitted MDD patients. Therapeutic interventions specifically targeting cognitive deficits in MDD are needed, even in the remitted state, to improve functional recovery, especially in patients who have a higher risk of cognitive deficit.

Telomere length as a predictor of response to Pioglitazone in patients with unremitted depression: a preliminary study

We studied peripheral leukocyte telomere length (LTL) as a predictor of antidepressant response to PPAR-γ agonist in patients with unremitted depression. In addition we examined correlation between LTL and the insulin resistance (IR) status in these subjects. Forty-two medically stable men and women ages 23-71 with non-remitted depression participated in double-blind placebo-controlled add-on of Pioglitazone to treatment-as-usual. Oral glucose tolerance tests were administered at baseline and at 12 weeks. Diagnostic evaluation of psychiatric disorders was performed at baseline and mood severity was followed weekly throughout the duration of the trial. At baseline, no differences in LTL were detected by depression severity, duration or chronicity. LTL was also not significantly different between insulin-resistant and insulin-sensitive subjects at baseline. Subjects with longer telomeres exhibited greater declines in depression severity in the active arm, but not in a placebo arm, P=0.005, r=-0.63, 95% confidence interval (95% CI)=(-0.84,-0.21). In addition, LTL predicted improvement in insulin sensitivity in the group overall and did not differ between intervention arms, P=0.036, r=-0.44, 95% CI=(-0.74,0.02) for the active arm, and P=0.026, r=-0.50, 95% CI=(-0.78,-0.03) for the placebo arm. LTL may emerge as a viable predictor of antidepressant response. An association between insulin sensitization and LTL regardless of the baseline IR status points to potential role of LTL as a non-specific moderator of metabolic improvement in these patients.

The Impact of Diabetes on Brain Function in Childhood and Adolescence

A constant supply of glucose to the brain is critical for normal cerebral metabolism. The dysglycemia of type 1 diabetes (T1D) can affect activity, survival, and function of neural cells. Clinical studies in T1D have shown impairments in brain morphology and function. The most neurotoxic milieu seems to be young age and/or diabetic ketoacidosis at onset, severe hypoglycemia under the age of 6 years followed by chronic hyperglycemia. Adverse cognitive outcomes seem to be associated with poorer mental health outcomes. It is imperative to improve outcomes by investigating the mechanisms of injury so that neuroprotective strategies independent of glycemia can be identified.

High glycemic index diet as a risk factor for depression: analyses from the Women's Health Initiative

BACKGROUND

The consumption of sweetened beverages, refined foods, and pastries has been shown to be associated with an increased risk of depression in longitudinal studies. However, any influence that refined carbohydrates has on mood could be commensurate with their proportion in the overall diet; studies are therefore needed that measure overall intakes of carbohydrate and sugar, glycemic index (GI), and glycemic load.

OBJECTIVE

We hypothesized that higher dietary GI and glycemic load would be associated with greater odds of the prevalence and incidence of depression.

DESIGN

This was a prospective cohort study to investigate the relations between dietary GI, glycemic load, and other carbohydrate measures (added sugars, total sugars, glucose, sucrose, lactose, fructose, starch, carbohydrate) and depression in postmenopausal women who participated in the Women's Health Initiative Observational Study at baseline between 1994 and 1998 (n = 87,618) and at the 3-y follow-up (n = 69,954).

RESULTS

We found a progressively higher dietary GI to be associated with increasing odds of incident depression in fully adjusted models (OR for the fifth compared with first quintile: 1.22; 95% CI: 1.09, 1.37), with the trend being statistically significant (P = 0.0032). Progressively higher consumption of dietary added sugars was also associated with increasing odds of incident depression (OR for the fifth compared with first quintile: 1.23; 95% CI: 1.07, 1.41; P-trend = 0.0029). Higher consumption of lactose, fiber, nonjuice fruit, and vegetables was significantly associated with lower odds of incident depression, and nonwhole/refined grain consumption was associated with increased odds of depression.

CONCLUSIONS

The results from this study suggest that high-GI diets could be a risk factor for depression in postmenopausal women. Randomized trials should be undertaken to examine the question of whether diets rich in low-GI foods could serve as treatments and primary preventive measures for depression in postmenopausal women.

Association between insulin resistance and cognition in patients with depressive disorders: exploratory analyses into age-specific effects

The current preliminary cross sectional study sought to examine the effects of insulin resistance (IR) and body mass index (BMI) on cognitive performance in adult patients with a history depression, currently not in an acute Major Depressive Episode (MDD). As an exploratory post hoc investigation, special consideration was given to adults <45 years and ≥45 years old. Subjects included men and women ages 19-71 (N = 39) with a history of a non-psychotic, non-melancholic MDD. All subjects underwent an insulin suppression test to determine Steady-State Plasma Glucose (SSPG), a battery of neuropsychological tests, and measurement of BMI. Multiple linear regressions were conducted to determine whether there were differential effects of direct (SSPG) and indirect (BMI) measures on cognition in the whole sample and within dichotomized age groups (<45 and ≥45 years). Preliminary results showed that in the sample as a whole, SSPG was not associated with worse performance on any cognitive variables, while higher BMI was associated with worse dominant hand fine motor skills. Within age groups, differential effects on cognition were found in relation to SSPG and BMI. Higher SSPG was associated with worse cognitive flexibility in the group <45 years, whereas higher BMI was associated with worse estimate of global intelligence in the group ≥45 years. The potential negative impact of IR in younger adults with depression raises concerns regarding the long-term impact on cognition and risk for Alzheimer's disease in undiagnosed younger adults with IR and depression. These negative consequences may not be seen with indirect measures of IR in younger adult populations. Overweight and obesity in older adults with a history of depression appear to have further negative impacts on cognition similar to deficits seen in patients with diabetes.

CLINICALTRIALSGOV IDENTIFIER

Clinical Trial NCT01106313.

Tryptophan breakdown is increased in euthymic overweight individuals with bipolar disorder: a preliminary report

OBJECTIVES

Individuals with bipolar disorder (BD) are disproportionately affected by symptoms of being overweight and metabolic syndrome when compared to the general population. The pertinence of this observation is underscored by observations that excess weight is associated with a more complex illness presentation, course, and outcome in BD. We present the first preliminary report of our BIPFAT study, which explored shared hypothesized pathophysiological pathways between being overweight and having BD.

METHODS

We investigated the tryptophan-kynurenine metabolism pathway as a proxy of dysregulated inflammatory homeostasis in euthymic, overweight individuals with BD (n = 78) compared to healthy controls (n = 156).

RESULTS

Both blood kynurenine concentrations and the kynurenine to tryptophan ratio [(Kyn:Trp); an estimate of tryptophan breakdown] were significantly higher in the total sample of euthymic patients with BD, with greater increases noted in both parameters in the subsample of overweight patients with BD. When compared to controls, peripheral neopterin concentrations were significantly lower. Within the BD group, there were also significant between-group differences in neopterin concentrations, with higher levels in those who were overweight and in subjects with BD in the later stages of illness compared to earlier stages.

CONCLUSIONS

Increased tryptophan breakdown, as well as neopterin levels in BD, may be an indirect mediator of immune-mediated inflammation. In BD, this may account for the high prevalence of medical comorbidities and increased mortality. The observation of increased kynurenine levels and Kyn:Trp, and altered circulating neopterin levels provides indirect evidence of increased activity of tryptophan-degrading indoleamine 2,3-dioxygenase in euthymic individuals with BD, underscoring the role of inflammatory mediators as a causative and/or consequent factor. More robust abnormalities in the overweight subsample underscore the additional inflammatory burden of medical comorbidity and suggest a shared pathophysiology as well as a mechanism mediating BD and cardiovascular disease.

Increased body mass index makes an impact on brain white-matter integrity in adults with remitted first-episode mania

BACKGROUND

Obesity is increasingly prevalent in bipolar disorder (BD) but data about the impact of elevated body mass index (BMI) on brain white-matter integrity in BD are sparse. Based on extant literature largely from structural magnetic resonance imaging (MRI) studies, we hypothesize that increased BMI is associated with decreased fractional anisotropy (FA) in the frontal, temporal, parietal and occipital brain regions early in the course of BD.

METHOD

A total of 26 euthymic adults (12 normal weight and 14 overweight/obese) with remitted first-episode mania (FEM) and 28 controls (13 normal weight and 15 overweight/obese) matched for age, handedness and years of education underwent structural MRI and diffusion tensor imaging scans.

RESULTS

There are significant effects of diagnosis by BMI interactions observed especially in the right parietal lobe (adjusted F(1,48) = 5.02, p = 0.030), occipital lobe (adjusted F(1,48) = 10.30, p = 0.002) and temporal lobe (adjusted F(1,48) = 7.92, p = 0.007). Specifically, decreased FA is found in the right parietal (F(1,48) = 5.864, p = 0.023) and occipital lobes (F(1,48) = 4.397, p = 0.047) within overweight/obese patients compared with normal-weight patients with FEM. Compared with overweight/obese controls, decreased FA is observed in right parietal (F(1,48) = 6.708, p = 0.015), temporal (F(1,48) = 10.751, p = 0.003) and occipital (F(1,48) = 9.531, p = 0.005) regions in overweight/obese patients with FEM.

CONCLUSIONS

Our findings suggest that increased BMI affects temporo-parietal-occipital brain white-matter integrity in FEM. This highlights the need to further elucidate the relationship between obesity and other neural substrates (including subcortical changes) in BD which may clarify brain circuits subserving the association between obesity and clinical outcomes in BD.

Obesity and bipolar disorder: synergistic neurotoxic effects?

Bipolar disorder (BD) is a disabling and chronic neuropsychiatric disorder that is typified by a complex illness presentation, episode recurrence and by its frequent association with psychiatric and medical comorbidities. Over the past decade, obesity has emerged as one of many comorbidities generating substantial concern in the BD population due to important prognostic implications. This comprehensive review details the bidirectional relationship between obesity and BD as evidenced by alterations in the structure and function of the central nervous system, in addition to greater depressive recurrence, cognitive dysfunction and risk of suicidality. Drawing on current research results, this article presents several putative mechanisms underlying the synergistic toxic effects and provides a framework for future treatment options for the obesity-BD comorbidity. There is a need for more large-scale prospective studies to investigate the bidirectional relationships between obesity and BD.

Basal ganglia morphology links the metabolic syndrome and depressive symptoms

The metabolic syndrome (MetS) is a clustering of cardiovascular and cerebrovascular risk factors that are often comorbid with depressive symptoms. Individual components of the MetS also covary with the morphology of basal ganglia regions that are altered by depression. However, it remains unknown whether the covariation between the MetS and depressive symptomatology can be accounted for in part by morphological changes in the basal ganglia. Accordingly, we tested the hypothesis that increased depressive symptoms among individuals with the MetS might be statistically mediated by reduced gray matter volume in basal ganglia regions. The presence of the MetS was determined in 147 middle-aged adults using the criteria of the National Cholesterol Education Program, Adult Treatment Panel III. Basal ganglia volumes were determined on an a priori basis by automated segmentation of high-resolution magnetic resonance images. Depressive symptoms were assessed using the Patient Health Questionnaire. Even after controlling for demographic and other confounding factors, having the MetS and meeting more MetS criteria covaried with reduced globus pallidus volume. Meeting more MetS criteria and reduced pallidal volume were also related to depressive symptoms. Moreover, the MetS-depression association was statistically mediated by pallidal volume. In summary, reduced globus pallidus volume is a neural correlate of the MetS that may partly account for its association with depressive symptoms.

Network-level structural abnormalities of cerebral cortex in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) usually begins in childhood and adolescence and causes lifelong damage to several major organs including the brain. Despite increasing evidence of T1DM-induced structural deficits in cortical regions implicated in higher cognitive and emotional functions, little is known whether and how the structural connectivity between these regions is altered in the T1DM brain. Using inter-regional covariance of cortical thickness measurements from high-resolution T1-weighted magnetic resonance data, we examined the topological organizations of cortical structural networks in 81 T1DM patients and 38 healthy subjects. We found a relative absence of hierarchically high-level hubs in the prefrontal lobe of T1DM patients, which suggests ineffective top-down control of the prefrontal cortex in T1DM. Furthermore, inter-network connections between the strategic/executive control system and systems subserving other cortical functions including language and mnemonic/emotional processing were also less integrated in T1DM patients than in healthy individuals. The current results provide structural evidence for T1DM-related dysfunctional cortical organization, which specifically underlie the top-down cognitive control of language, memory, and emotion.

Effects of diabetes on hippocampal neurogenesis: links to cognition and depression

Diabetes often leads to a number of complications involving brain function, including cognitive decline and depression. In addition, depression is a risk factor for developing diabetes. A loss of hippocampal neuroplasticity, which impairs the ability of the brain to adapt and reorganize key behavioral and emotional functions, provides a framework for understanding this reciprocal relationship. The effects of diabetes on brain and behavioral functions in experimental models of type 1 and type 2 diabetes are reviewed, with a focus on the negative impact of impaired hippocampal neurogenesis, dendritic remodeling and increased apoptosis. Mechanisms shown to regulate neuroplasticity and behavior in diabetes models, including stress hormones, neurotransmitters, neurotrophins, inflammation and aging, are integrated within this framework. Pathological changes in hippocampal function can contribute to the brain symptoms of diabetes-associated complications by failing to regulate the hypothalamic-pituitary-axis, maintain learning and memory and govern emotional expression. Further characterization of alterations in neuroplasticity along with glycemic control will facilitate the development and evaluation of pharmacological interventions that could successfully prevent and/or reverse the detrimental effects of diabetes on brain and behavior.

[Diabetes mellitus and depressive disorder, an undesirable association]

Type 2 diabetes and depressive disorder are 2 chronic diseases highly prevalent in developed countries and with a negative impact on quality of life and life expectancy. In recent years, both conditions have been shown to be strongly associated. Thus, diabetics have an increased risk of suffering depressive disorder, as well as impaired glucose homeostasis, if they experience depression. In diabetic patients, concurrent depression is associated to greater difficulties in disease management and metabolic control, increased risk of developing chronic complications, decreased quality of life, and higher healthcare expenses. As a result, the interest of diabetic scientific societies in this association has increased, and they recommend regular mood assessment in diabetic patients. However, the limited clinical experience available and the conflicting results reported to date make it difficult to draw conclusions.

Prefrontal cortical deficits in type 1 diabetes mellitus: brain correlates of comorbid depression

CONTEXT Neural substrates that may be responsible for the high prevalence of depression in type 1 diabetes mellitus (T1DM) have not yet been elucidated. OBJECTIVE To investigate neuroanatomic correlates of depression in T1DM. DESIGN Case-control study using high-resolution brain magnetic resonance images. SETTINGS Joslin Diabetes Center and McLean Hospital, Massachusetts, and Seoul National University Hospital, South Korea. PARTICIPANTS A total of 125 patients with T1DM (44 subjects with ≥1 previous depressive episodes [T1DM-depression group] and 81 subjects who had never experienced depressive episodes [T1DM-only group]), 23 subjects without T1DM but with 1 or more previous depressive episodes (depression group), and 38 healthy subjects (control group). MAIN OUTCOME MEASURES Spatial distributions of cortical thickness for each diagnostic group were compared with the control group using a surface-based approach. Among patients with T1DM, associations between metabolic control measures and cortical thickness deficits were examined. RESULTS Thickness reduction in the bilateral superior prefrontal cortical regions was observed in the T1DM-depression, T1DM-only, and depression groups relative to the control group at corrected P &lt; .01. Conjunction analyses demonstrated that thickness reductions related to the influence of T1DM and those related to past depressive episode influence were observed primarily in the superior prefrontal cortical region. Long-term glycemic control levels were associated with superior prefrontal cortical deficits in patients with T1DM (β = -0.19, P = .02). CONCLUSIONS This study provides evidence that thickness reduction of prefrontal cortical regions in patients with T1DM, as modified by long-term glycemic control, could contribute to the increased risk for comorbid depression.

A review of electroencephalographic changes in diabetes mellitus in relation to major depressive disorder

A bidirectional relationship exists between diabetes mellitus (DM) and major depressive disorder (MDD), with depression commonly reported in both type 1 DM (T1DM) and type 2 DM (T2DM), and depressive symptoms associated with a higher incidence of diabetes. However, how the two conditions are pathologically connected is not completely understood. Similar neurophysiological abnormalities have been reported in both DM and MDD, including elevated electroencephalographic (EEG) activity in low-frequency slow waves and increased latency and/or reduced amplitude of event-related potentials. It is possible that this association reflects some common underlying pathology, and it has been proposed that diabetes may place patients at risk for depression through a biological mechanism linking the metabolic changes of DM to changes in the central nervous system. In this review we will discuss EEG abnormalities in DM, as well as the biological mechanisms underlying various EEG parameters, in order to evaluate whether or not a common EEG biosignature exists between DM and MDD. Identifying such commonalities could significantly inform the current understanding of the mechanisms that subserve the development of the two conditions. Moreover, this new insight may provide the basis for informing new drug discovery capable of mitigating and possibly even preventing both conditions.

Age-related loss of brain volume and T2 relaxation time in youth with type 1 diabetes

OBJECTIVE

2 Childhood-onset type 1 diabetes is associated with neurocognitive deficits, but there is limited evidence to date regarding associated neuroanatomical brain changes and their relationship to illness variables such as age at disease onset. This report examines age-related changes in volume and T2 relaxation time (a fundamental parameter of magnetic resonance imaging that reflects tissue health) across the whole brain.

RESEARCH DESIGN AND METHODS

Type 1 diabetes, N = 79 (mean age 20.32 ± 4.24 years), and healthy control participants, N = 50 (mean age 20.53 ± 3.60 years). There were no substantial group differences on socioeconomic status, sex ratio, or intelligence quotient.

RESULTS

Regression analyses revealed a negative correlation between age and brain changes, with decreasing gray matter volume and T2 relaxation time with age in multiple brain regions in the type 1 diabetes group. In comparison, the age-related decline in the control group was small. Examination of the interaction of group and age confirmed a group difference (type 1 diabetes vs. control) in the relationship between age and brain volume/T2 relaxation time.

CONCLUSIONS

We demonstrated an interaction between age and group in predicting brain volumes and T2 relaxation time such that there was a decline in these outcomes in type 1 diabetic participants that was much less evident in control subjects. Findings suggest the neurodevelopmental pathways of youth with type 1 diabetes have diverged from those of their healthy peers by late adolescence and early adulthood but the explanation for this phenomenon remains to be clarified.

Central nervous system: a conductor orchestrating metabolic regulations harmed by both hyperglycaemia and hypoglycaemia

Recent evidence suggests that the brain has a key role in the control of energy metabolism, body fat content and glucose metabolism. Neuronal systems, which regulate energy intake, energy expenditure, and endogenous glucose production, sense and respond to input from hormonal and nutrient-related signals that convey information regarding both body energy stores and current energy availability. In response to this input, adaptive changes occur that promote energy homeostasis and the maintenance of blood glucose levels in the normal range. Defects in this control system are implicated in the link between obesity and type 2 diabetes mellitus. The central nervous system may be considered the conductor of an orchestra involving many peripheral organs involved in these homeostatic processes. However, the brain is mainly a glucose-dependent organ, which can be damaged by both hypoglycaemia and hyperglycaemia. Hypoglycaemia unawareness is a major problem in clinical practice and is associated with an increased risk of coma. Stroke is another acute complication associated with diabetes mellitus, especially in elderly people, and the control of glucose level in this emergency situation remains challenging. The prognosis of stroke is worse in diabetic patients and both its prevention and management in at-risk patients should be improved. Finally, chronic diabetic encephalopathies, which may lead to cognitive dysfunction and even dementia, are also recognized. They may result from recurrent hypoglycaemia and/or from chronic hyperglycaemia leading to cerebral vascular damage. Functional imaging is of interest for exploring diabetes-associated cerebral abnormalities. Thus, the intimate relationship between the brain and diabetes is increasingly acknowledged in both research and clinical practice.