Mental disorders in diabetic patients with mitochondrial transfer RNA(Leu) (UUR) mutation at position 3243

Monoamine Oxidase: A Potential Link in Papez Circuit to Generalized Anxiety Disorders

Anxiety is a common mental illness that affects a large number of people around the world, and its treatment is often based on the use of pharmacological substances such as benzodiazepines, serotonin, and 5-hydroxytyrosine (MAO) neurotransmitters. MAO neurotransmitters levels are deciding factors in the biological effects. This review summarizes the current understanding of the MAO system and its role in the modulation of anxiety-related brain circuits and behavior. The MAO-A polymorphisms have been implicated in the susceptibility to generalized anxiety disorder (GAD) in several investigations. The 5-HT system is involved in a wide range of physiological and behavioral processes, involving anxiety, aggressiveness, stress reactions, and other elements of emotional intensity. Among these, 5-HT, NA, and DA are the traditional 5-HT neurons that govern a range of biological activities, including sleep, alertness, eating, thermoregulation, pains, emotion, and memory, as anticipated considering their broad projection distribution in distinct brain locations. The DNMTs (DNA methyltransferase) protein family, which increasingly leads a prominent role in epigenetics, is connected with lower transcriptional activity and activates DNA methylation. In this paper, we provide an overview of the current state of the art in the elucidation of the brain's complex functions in the regulation of anxiety.

The non-syndromic clinical spectrums of mtDNA 3243A>G mutation

The m.3243A >G mutation in the tRNA Leu (UUR) gene (MT-TL1) of the mitochondrial DNA is the most widely seen pathogenic mtDNA mutation which has major phenotypic variations. The clinical phenotype involves various organs such as the brain and nerves, skeletal muscles, heart, endocrine system, gastrointestinal tract, and skin. Some phenotypes conform to well established syndromes, while most of the symptoms appear individually or concomitant to other syndromes, making identification difficult. Furthermore, some progress has been made on cardiac manifestations as well as complications during pregnancy and perinatal period. This article provides a systematic review of the non-syndromic phenotypes and latest developments in m.3243A>G mutation.

A metabolome-wide association study in the general population reveals decreased levels of serum laurylcarnitine in people with depression

Depression constitutes a leading cause of disability worldwide. Despite extensive research on its interaction with psychobiological factors, associated pathways are far from being elucidated. Metabolomics, assessing the final products of complex biochemical reactions, has emerged as a valuable tool for exploring molecular pathways. We conducted a metabolome-wide association analysis to investigate the link between the serum metabolome and depressed mood (DM) in 1411 participants of the KORA (Cooperative Health Research in the Augsburg Region) F4 study (discovery cohort). Serum metabolomics data comprised 353 unique metabolites measured by Metabolon. We identified 72 (5.1%) KORA participants with DM. Linear regression tests were conducted modeling each metabolite value by DM status, adjusted for age, sex, body-mass index, antihypertensive, cardiovascular, antidiabetic, and thyroid gland hormone drugs, corticoids and antidepressants. Sensitivity analyses were performed in subcohorts stratified for sex, suicidal ideation, and use of antidepressants. We replicated our results in an independent sample of 968 participants of the SHIP-Trend (Study of Health in Pomerania) study including 52 (5.4%) individuals with DM (replication cohort). We found significantly lower laurylcarnitine levels in KORA F4 participants with DM after multiple testing correction according to Benjamini/Hochberg. This finding was replicated in the independent SHIP-Trend study. Laurylcarnitine remained significantly associated (p value < 0.05) with depression in samples stratified for sex, suicidal ideation, and antidepressant medication. Decreased blood laurylcarnitine levels in depressed individuals may point to impaired fatty acid oxidation and/or mitochondrial function in depressive disorders, possibly representing a novel therapeutic target.

Joint trajectories of cigarette smoking and depressive symptoms from the mid-20s to the mid-30s predicting generalized anxiety disorder

The current study examines longitudinal patterns of cigarette smoking and depressive symptoms as predictors of generalized anxiety disorder using data from the Harlem Longitudinal Development Study. There were 674 African American (53%) and Puerto Rican (47%) participants. Among the 674 participants, 60% were females. In the logistic regression analyses, the indicators of membership in each of the joint trajectories of cigarette smoking and depressive symptoms from the mid-20s to the mid-30s were used as the independent variables, and the diagnosis of generalized anxiety disorder in the mid-30s was used as the dependent variable. The high cigarette smoking with high depressive symptoms group and the low cigarette smoking with high depressive symptoms group were associated with an increased likelihood of having generalized anxiety disorder as compared to the no cigarette smoking with low depressive symptoms group. The findings shed light on the prevention and treatment of generalized anxiety disorder.

Neuropsychiatric Features in Primary Mitochondrial Disease

Mitochondrial diseases are a clinically heterogeneous group of disorders that ultimately result from dysfunction of the mitochondrial respiratory chain. There is some evidence to suggest that mitochondrial dysfunction plays a role in neuropsychiatric illness; however, the data are inconclusive. This article summarizes the available literature published in the area of neuropsychiatric manifestations in both children and adults with primary mitochondrial disease, with a focus on autism spectrum disorder in children and mood disorders and schizophrenia in adults.

How cigarette smoking may increase the risk of anxiety symptoms and anxiety disorders: a critical review of biological pathways

Multiple studies have demonstrated an association between cigarette smoking and increased anxiety symptoms or disorders, with early life exposures potentially predisposing to enhanced anxiety responses in later life. Explanatory models support a potential role for neurotransmitter systems, inflammation, oxidative and nitrosative stress, mitochondrial dysfunction, neurotrophins and neurogenesis, and epigenetic effects, in anxiety pathogenesis. All of these pathways are affected by exposure to cigarette smoke components, including nicotine and free radicals. This review critically examines and summarizes the literature exploring the role of these systems in increased anxiety and how exposure to cigarette smoke may contribute to this pathology at a biological level. Further, this review explores the effects of cigarette smoke on normal neurodevelopment and anxiety control, suggesting how exposure in early life (prenatal, infancy, and adolescence) may predispose to higher anxiety in later life. A large heterogenous literature was reviewed that detailed the association between cigarette smoking and anxiety symptoms and disorders with structural brain changes, inflammation, and cell-mediated immune markers, markers of oxidative and nitrosative stress, mitochondrial function, neurotransmitter systems, neurotrophins and neurogenesis. Some preliminary data were found for potential epigenetic effects. The literature provides some support for a potential interaction between cigarette smoking, anxiety symptoms and disorders, and the above pathways; however, limitations exist particularly in delineating causative effects. The literature also provides insight into potential effects of cigarette smoke, in particular nicotine, on neurodevelopment. The potential treatment implications of these findings are discussed in regards to future therapeutic targets for anxiety. The aforementioned pathways may help mediate increased anxiety seen in people who smoke. Further research into the specific actions of nicotine and other cigarette components on these pathways, and how these pathways interact, may provide insights that lead to new treatment for anxiety and a greater understanding of anxiety pathogenesis.

Depressive episode with catatonic features in a case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)

Three months previously, a 17-year-old girl had complained of right-hand side hemiparesis, and her brain magnetic resonance imaging (MRI) showed a signal change in the left temporoparietooccipital area. The 3243A>G mutation was found in mitochondrial DNA. She was diagnosed with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and was prescribed dichloroacetic acid to treat lactic acidosis. Her health improved. Two months later, she developed drowsiness and generalized weakness. A New lesion was not found on brain MRI, and electrodiagnostic findings were compatible with acute motor sensory axonal neuropathy. Her negative symptoms, such as depressed mood, loss of interest in activities, psychomotor retardation, and hypersomnia, were aggravated. She was prescribed antidepressants and psychostimulants by a psychiatrist after diagnosis of severe depression episode with catatonic features. One month later, her catatonic condition had improved with medication. Our experience shows that psychiatric diagnostic evaluation of abruptly regressed neurologic and clinical features is important, even in a patient with devastating underlying disease.

Relationship of cerebrospinal fluid glucose metabolites to MRI deep white matter hyperintensities and treatment resistance in bipolar disorder patients

OBJECTIVES

Both diabetes mellitus and magnetic resonance image (MRI) deep white matter hyperintensities (WMHs) are more common in bipolar disorder (BD) patients than in matched controls. Deep-as opposed to periventricular--WMHs and diabetes are associated with treatment resistance and poorer outcome. This study investigated whether brain glucose metabolism by the polyol pathway--a pathway linked to nervous tissue disease in diabetes--is related to deep WMH volume and treatment resistance in BD patients.

METHODS

Volumes of fluid-attenuated inversion recovery WMHs were quantified and correlated with cerebrospinal fluid (CSF) concentrations of glucose metabolites in 20 nondiabetic patients with BD and nondiabetic comparison subjects with schizophrenia (n = 15) or transient neurologic symptoms (neurologic controls, n = 15).

RESULTS

BD patients, but not schizophrenic patients, had significantly greater volumes of deep but not periventricular WMHs compared to neurologic controls. BD subjects also had significantly greater CSF concentrations of sorbitol and fructose (the polyol pathway metabolites of glucose) compared to controls. Significant positive correlations between CSF metabolites and WMH volumes were found only in the BD group and were between deep WMH volumes and CSF sorbitol (rho = 0.487, p = 0.029) and fructose (rho = 0.474, p = 0.035). An index of treatment resistance correlated significantly with deep WMH volume (rho = 0.578, p = 0.008), sorbitol (rho = 0.542, p = 0.013), and fructose (rho = 0.692, p = 0.001) in BD subjects but not in other subjects.

CONCLUSIONS

This is the first reported evidence of relationships between abnormal brain glucose metabolism and both deep WMHs and treatment resistance in a group of BD patients. Further studies are necessary to determine the significance of these findings to BD pathophysiology.

Clinical features, diagnosis and management of maternally inherited diabetes and deafness (MIDD) associated with the 3243A>G mitochondrial point mutation

Maternally inherited diabetes and deafness (MIDD) affects up to 1% of patients with diabetes but is often unrecognized by physicians. It is important to make an accurate genetic diagnosis, as there are implications for clinical investigation, diagnosis, management and genetic counselling. This review summarizes the range of clinical phenotypes associated with MIDD; outlines the advances in genetic diagnosis and pathogenesis of MIDD; summarizes the published prevalence data and provides guidance on the clinical management of these patients and their families.

Psychiatric comorbidity in 36 adults with mitochondrial cytopathies

INTRODUCTION

Mitochondria are intracellular organelles involved in adenosine triphosphate production. The literature has established the presence of mitochondrial dysfunction in some subjects with psychiatric disorders. Also, there are multiple reports of patients with mitochondrial dysfunction who have various psychiatric disorders. Although the literature on mitochondrial dysfunction and its relation to psychiatric disorders is growing, there remain many unanswered questions.

OBJECTIVE

To review subjects with mitochondrial cytopathies for prevalence of psychiatric comorbidity.

METHODS

For this study, 36 adults were interviewed. The Mini International Neuropsychiatric Interview and the Short-Form 36 Health Survey, version 1 were used.

RESULTS

Lifetime diagnoses included 54% major depressive disorder, 17% bipolar disorder, and 11% panic disorder. These prevalence rates are compared with the general population and subjects with cancer and epilepsy. Subjects with a comorbid psychiatric diagnosis were older (P=.05), had more hospital admissions (P=.02), more medical conditions (P=.01), and lower quality of life (P=.01) than subjects with mitochondrial disease alone.

CONCLUSION

Clinicians caring for persons with mitochondrial cytopathies should note the high prevalence of psychiatric problems. Also, this comorbidity might have etiological and therapeutic implications.

Review of the literature on major mental disorders in adult patients with mitochondrial diseases

Mitochondria are intracellular organelles crucial to the production cellular energy. Mitochondrial disease results from a malfunction in this biochemical cascade. These disorders can affect any organ system, producing diverse signs and symptoms, including psychiatric ones. Several authors argue that mitochondrial dysfunction is related to the pathophysiology of bipolar disorder and schizophrenia. Also, the authors retrieved 19 case reports that describe patients with mitochondrial diseases and psychiatric disorders. Most of these patients have psychiatric presentations that preceded the diagnosis of mitochondrial disease. The most common physical findings are fatigue, muscle weakness with or without atrophy, and hearing loss.

Mitochondrial DNA 3243A>G mutation and increased expression of LARS2 gene in the brains of patients with bipolar disorder and schizophrenia

BACKGROUND

Accumulating evidence suggests mitochondrial dysfunction in bipolar disorder. Analyses of mitochondria-related genes using DNA microarray showed significantly increased LARS2 (mitochondrial leucyl-tRNA synthetase) in the postmortem prefrontal cortices of patients with bipolar disorder provided by the Stanley Foundation Brain Collection. LARS2 is a nuclear gene encoding the enzyme catalyzing the aminoacylation of mitochondrial tRNA(Leu). A well-studied mitochondrial DNA point mutation, 3243A>G, in the region of tRNA(Leu (UUR)), related with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes), is known to decrease the efficiency of aminoacylation of tRNA(Leu (UUR)).

METHODS

The steady state level of LARS2 was examined in the transmitochondrial cybrids carrying 3243A>G. We examined the 3243A>G mutation in these brains using the peptide nucleic acid-clamped polymerase chain reaction restriction fragment length polymorphism method.

RESULTS

LARS2 was upregulated in the transmitochrondrial cybrids carrying 3243A>G. The 3243A>G was detected in the postmortem brains of two patients with bipolar disorder and one with schizophrenia. These patients also showed higher levels of the mutation in their livers and significantly higher gene expression of LARS2 compared with other subjects.

CONCLUSIONS

These results suggest that upregulation of LARS2 is a hallmark of 324A>G mutation. The accumulation of 3243A>G mutation in the brain may have a pathophysiologic role in bipolar disorder and schizophrenia.

Alterations of rCBF and mitochondrial dysfunction in major depressive disorder: a case report

OBJECTIVE

A mitochondrial disease might be considered when depressive disorder is associated with diabetes mellitus or other symptoms commonly found in mitochondrial disease. Scattered regional cerebral blood flow (rCBF) decreases and increases have been reported in depressive and mitochondrial disorders. A 61-year-old male patient with early adult onset of depressive disorder and a slowly developing multiorgan syndrome including diabetes mellitus was investigated.

METHOD

99mTc-HMPAO rCBF SPECT and muscle biopsy to assess mitochondrial functions were performed in the patient.

RESULTS

Alterations of rCBF were found in the patient, with the most pronounced decreases in the left dorsolateral frontal and inferior parietal lobes, and the most pronounced increases in the bilateral superior parietal lobes. Muscle biopsy revealed myopathy and decrease of mitochondrial adenosine triphosphate production rates (MAPRs).

CONCLUSION

The MAPRs decreases support the suspicion of mitochondrial dysfunction in the patient. A subgroup of depressed patients may have mitochondrial dysfunctions.

Manic-depression genes and the new millennium: poised for discovery

Manic-depressive illness is a common psychiatric disorder with complex etiology that likely involves multiple genes and non-genetic influences. The uncertain path to gene discovery has spurred considerable debate over genetic findings and gene-finding strategies. In this article, I review the main findings, with a focus on: (1) putative linked loci on chromosomes 1q31-32, 4p16, 6pter-p24, 10p14, 10q21-26, 12q23-24, 13q31-32, 18p11, 18q21-23, 21q22, 22q11-13, and Xq24-28; and (2) association studies with candidate genes, dynamic mutations, mitochondrial mutations, and chromosomal aberrations. Although no gene has been identified, promising findings are emerging. I then discuss the challenges and opportunities ahead, with special emphasis on gene-finding methods-in particular, questions pertaining to phenotype definition, linkage and association mapping, gene markers, sampling, study population, multigene systems, lessons from other disorders, animal models, and bioinformatics. The progress to date, together with rapid advances in genomics, analytical and computational methods, and bioinformatics, holds promise for new insights into the genetics of manic-depression, in the new millennium.

The other, forgotten genome: mitochondrial DNA and mental disorders

This paper summarizes recent research on mitochondrial DNA (mtDNA)--which might be described as the "other, forgotten genome". Recent studies suggest the possible pathophysiological significance of mtDNA in schizophrenia and neurodegenerative and mood disorders. Decreased activity of the mitochondrial electron transport chain has been implicated in both Parkinson's and Alzheimer's disease and while age-related accumulation of mtDNA deletions has been suggested as a possible cause, there is no concrete evidence that particular mtDNA polymorphisms are responsible. In schizophrenia, the activity and/or mRNA expression of complex IV are involved, but the direction of the alteration is not the same and there is no evidence linking schizophrenia with mtDNA. In bipolar disorder, there is some evidence of parent-of-origin effects and association with mtDNA polymorphisms but further investigation is needed to elucidate the role of mtDNA in mental disorders.

Mitochondrial disease: a pulmonary and critical-care medicine perspective

The clinical spectrum of mitochondrial diseases has expanded dramatically in the last decade. Abnormalities of mitochondrial function are now thought to participate in a number of common adult diseases, ranging from exercise intolerance to aging. This review outlines the common presentations of mitochondrial disease in ICUs and in the outpatient setting and discusses current diagnostic and therapeutic options as they pertain to the pulmonary and critical-care physician.

Involvement of nervous system in maternally inherited diabetes and deafness (MIDD) with the A3243G mutation of mitochondrial DNA

OBJECTIVES

The A3243G mutation of mitochondrial DNA (mtDNA) has been associated with maternally inherited diabetes and deafness (MIDD) in a number of reports; however, the involvement of the nervous system has rarely been mentioned, prompting this exploration of the manifestation of neurological disorders in MIDD cases.

MATERIAL AND METHODS

We investigated four generations of a large Taiwanese family in which MIDD is manifest. We conducted a series of clinical examinations, including computed tomography (CT) and magnetic resonance imaging (MRI) of the head, brain 99mTc-HMPAO single photon emission computed tomography (SPECT), cognitive function tests, and nerve conduction velocity (NCV) studies. Blood levels of creatine kinase (CK) and lactate, pathology of muscle biopsy samples and proportions of mutant mtDNA in blood cells, hair follicles, muscle and skin were also analyzed. Mean follow-up period was 4 years.

RESULTS

The patients exhibited the clinical features of diabetes mellitus including sensorineural hearing loss, short stature, and/or histories of spontaneous abortion. No stroke-like episodes were reported. Analysis for mtDNA revealed that the A3243G mutation existed in 11 members (6 symptomatic and 5 asymptomatic members) of this MIDD-prone family, with the proportion of mutant mtDNA ranging from 21% to 47% in leukocytes. Head CT revealed diffuse brain atrophy for all 6 (100%) patients examined and bilateral basal ganglia calcification in 4 of 6 (67%) patients. Brain 99mTc-HMPAO SPECT revealed diminished uptake in the bilateral parieto-occipital or occipital regions for all 6 tested patients, cognitive function for these patients was normal. Results of head CT and SPECT were normal in one asymptomatic member of the family. One muscle biopsy revealed abundant ragged-red fibers with modified Gomori-trichrome stain. Muscle-enzyme activity and serum-lactate levels were normal.

CONCLUSION

We have demonstrated that a wide spectrum of sub clinical pathologies of the central nervous system and muscle are present for this MIDD-prone family, none of whom developed typical MELAS during the 4-year period of follow-up study.

Mitochondrial DNA polymorphisms in bipolar disorder

BACKGROUND

Previous studies suggested mitochondrial abnormality in bipolar disorder: (1) possible contribution of parent-of-origin effect in transmission of bipolar disorder; (2) abnormal brain phosphorus metabolism detected by phosphorus-31 magnetic resonance spectroscopy; (3) comorbidity of affective disorders in patients with mitochondrial encephalopathy; (4) increased levels of the 4977bp deletion of mitochondrial DNA (mtDNA) in the postmortem brains. We investigated mtDNA polymorphisms in association with bipolar disorder.

METHODS

Twelve PCR fragments including all tRNA genes were examined by the single-strand conformation polymorphism method in 43 bipolar patients. All observed polymorphisms were sequenced. Association of these polymorphisms with bipolar disorder was examined by restriction fragment length polymorphism method in 135 bipolar patients and 187 controls.

RESULTS

In total, we found 28 polymorphisms including 14 polymorphisms that have not been reported previously. The A10398G polymorphism was significantly associated with bipolar disorder (10398A genotype: 33.1% in bipolar, 22.2% in the control, P<0.05). Although this difference was not significant after Bonferroni correction, the CA haplotype of the 5178 and 10398 polymorphisms was still significantly associated with bipolar disorder (CA haplotype: 33.6% in bipolar, 16.8% in control, P<0.001). Three rare mutations substituting evolutionary conserved bases; A5539G in tRNA(Trp) gene, A5747G in the origin of L-strand replication, and A8537G in ATPase subunit-6 and -8 genes, were found in patients with family history in which maternal transmission was suspected.

DISCUSSION

The 5178C/10398A haplotype in mtDNA may be a risk factor of bipolar disorder (odds ratio, 2.4). Pathophysiological significance of rare mtDNA mutations needs to be verified in the future. This finding may imply the pathophysiological significance of mtDNA in bipolar disorder.

Mitochondrial dysfunction in bipolar disorder

Mitochondrial dysfunction is implicated in bipolar disorder based on the following lines of evidence: 1) Abnormal brain energy metabolism measured by 31P-magnetic resonance spectroscopy, that is, decreased intracellular pH, decreased phosphocreatine (PCr), and enhanced response of PCr to photic stimulation. 2) Possible role of maternal inheritance in the transmission of bipolar disorder. 3) Increased levels of the 4977-bp deletion in mitochondrial DNA (mtDNA) in autopsied brains. 4) Comorbidity of affective disorders in certain types of mitochondrial disorders, such as autosomal inherited chronic progressive external ophthalmoplegia and mitochondrial diabetes mellitus with the 3243 mutation. Based on these findings, we searched for mtDNA mutations/ polymorphisms associated with bipolar disorder and found that 5178C and 10398A polymorphisms in mtDNA were risk factors for bipolar disorder. The 5178C genotype was associated with lower brain intracellular pH. mtDNA variations may play a part in the pathophysiology of bipolar disorder through alteration of intracellular calcium signaling systems. The mitochondrial dysfunction hypothesis, which comprehensively accounts for the pathophysiology of bipolar disorder, is proposed.

Mitochondrial genetic analyses suggest selection against maternal lineages in bipolar affective disorder

Previous reports of preferential transmission of bipolar affective disorder (BP) from the maternal versus the paternal lines in families suggested that this disorder may be caused by mitochondrial DNA mutations. We have sequenced the mitochondrial genome in 25 BP patients with family histories of psychiatric disorder that suggest matrilineal inheritance. No polymorphism identified more than once in this sequencing showed any significant association with BP in association studies using 94 cases and 94 controls. To determine whether our BP sample showed evidence of selection against the maternal lineage, we determined genetic distances between all possible pairwise comparisons within the BP and control groups, based on multilocus mitochondrial polymorphism haplotypes. These analyses revealed fewer closely related haplotypes in the BP group than in the matched control group, suggesting selection against maternal lineages in this disease. Such selection is compatible with recurrent mitochondrial mutations, which are associated with slightly decreased fitness. Although such mismatch distribution comparisons have been used previously for analyses of population histories, this is, as far as we are aware, the first report of this method being used to study disease.

Depression and bipolar disorder: relationships to impaired fatty acid and phospholipid metabolism and to diabetes, cardiovascular disease, immunological abnormalities, cancer, ageing and osteoporosis. Possible candidate genes

Depression and bipolar disorder are two of the commonest illnesses in the developed world. While some patients can be treated effectively with available drugs, many do not respond, especially in the depression related to bipolar disorder. Depression is associated with diabetes, cardiovascular disease, immunological abnormalities, multiple sclerosis, cancer, osteoporosis and ageing: in each case depressed individuals have a worse outcome than non-depressed individuals. In all of these conditions there is now evidence of impaired phospholipid metabolism and impaired fatty acid-related signal transduction processes. Impaired fatty acid and phospholipid metabolism may be a primary cause of depression in many patients and may explain the interactions with other diseases. Several novel gene candidates for involvement in depression and bipolar disorder are proposed.