TRH stimulation and dexamethasone suppression in borderline personality disorder

Targeting the Endocannabinoid System in Borderline Personality Disorder: Corticolimbic and Hypothalamic Perspectives

Borderline Personality Disorder (BPD) is a chronic debilitating psychiatric disorder characterized mainly by emotional instability, chaotic interpersonal relationships, cognitive disturbance (e.g., dissociation and suicidal thoughts) and maladaptive behaviors. BPD has a high rate of comorbidity with other mental disorders and a high burden on society. In this review, we focused on two compromised brain regions in BPD - the hypothalamus and the corticolimbic system, emphasizing the involvement and potential contribution of the endocannabinoid system (ECS) to improvement in symptoms and coping. The hypothalamus-regulated endocrine axes (hypothalamic pituitary - gonadal, thyroid & adrenal) have been found to be dysregulated in BPD. There is also substantial evidence for limbic system structural and functional changes in BPD, especially in the amygdala and hippocampus, including cortical regions within the corticolimbic system. Extensive expression of CB1 and CB2 receptors of the ECS has been found in limbic regions and the hypothalamus. This opens new windows of opportunity for treatment with cannabinoids such as cannabidiol (CBD) as no other pharmacological treatment has shown long-lasting improvement in the BPD population to date. This review aims to show the potential role of the ECS in BPD patients through their most affected brain regions, the hypothalamus and the corticolimbic system. The literature reviewed does not allow for general indications of treatment with CBD in BPD. However, there is enough knowledge to indicate a treatment ratio of a high level of CBD to a low level of THC. A randomized controlled trial investigating the efficacy of cannabinoid based treatments in BPD is warranted.

The dexamethasone suppression test and DSM-III-R diagnoses in suicide attempters

Previous research on hypothalamic-pituitary adrenal (HPA) axis-activity in suicide attempter research has shown conflicting outcomes. The design of the present study was to test the influence of personality disorders and concominant axis I diagnoses on the dexamethasone suppression diagnostic test by use of multiple regression analyses. The sample consisted of 184 patients with a recent suicide attempt and 42 healthy controls. As expected, the lowest pre- and postdexamethasone cortisol levels were found in patients with personality disorders axis II, cluster B as compared to the other patients. The results remained significant when analysed for covariance with DSM-III-R axis I diagnoses, age or sex. Whether these low cortisol levels are due to previous experience of extreme stressful events or long-lasting burden, or whether they may be a consequence of biogenetic or psychological predisposal of interest, remains to be elucidated. Axis I comorbidity needs to be further examined.

Hypothalamic-pituitary-adrenal axis functioning in borderline personality disorder: A meta-analysis

Borderline Personality Disorder (BPD) has been associated with altered hypothalamic-pituitary-adrenal (HPA) axis functioning. However, evidence is inconsistent. Therefore, the present series of meta-analyses aimed to quantify HPA axis functioning in BPD patients based on singular and continuous cortisol assessments and measures of reactivity to pharmacological and psychosocial stress. Case-control studies comparing adult BPD patients and healthy and clinical controls were considered for inclusion. The search resulted in 804 publications, of which 37 studies (k = 81; BPD n = 803, controls n = 1092) were included. Analyses were based on random effect models using standardized mean differences. BPD patients displayed elevated continuous cortisol output and blunted cortisol following psychosocial challenges. Singular cortisol assessments and cortisol after pharmacological challenges were not significantly different. Meta-analyses were limited by inconsistent reporting in individual studies and small samples for some comparisons. Due to the debilitating nature of stress-related symptoms in BPD, more research on elevated continuous cortisol output and blunted cortisol responses to psychosocial stress is warranted.

A Neurobiological Model of Borderline Personality Disorder: Systematic and Integrative Review

Borderline personality disorder (BPD) is a severe mental disorder with a multifactorial etiology. The development and maintenance of BPD is sustained by diverse neurobiological factors that contribute to the disorder's complex clinical phenotype. These factors may be identified using a range of techniques to probe alterations in brain systems that underlie BPD. We systematically searched the scientific literature for empirical studies on the neurobiology of BPD, identifying 146 articles in three broad research areas: neuroendocrinology and biological specimens; structural neuroimaging; and functional neuroimaging. We consolidate the results of these studies and provide an integrative model that attempts to incorporate the heterogeneous findings. The model specifies interactions among endogenous stress hormones, neurometabolism, and brain structures and circuits involved in emotion and cognition. The role of the amygdala in BPD is expanded to consider its functions in coordinating the brain's dynamic evaluation of the relevance of emotional stimuli in the context of an individual's goals and motivations. Future directions for neurobiological research on BPD are discussed, including implications for the Research Domain Criteria framework, accelerating genetics research by incorporating endophenotypes and gene × environment interactions, and exploring novel applications of neuroscience findings to treatment research.

Depression-related differences in lean body mass distribution from National Health and Nutrition Examination Survey 2005-2006

BACKGROUND

Although the association between depression and body composition has been widely discussed, the effects of depression on lean body mass (LBM) are unclear. The present study aimed to investigate the association of depression with LBM.

METHODS

The study included 2406 participants aged 18-69 years. The sex and body mass index (BMI) stratified analysis of covariance was performed to compare total LBM and percentage LBM (%LBM) in subjects with different depression score levels. Multiple linear regression analysis was conducted to estimate the association between depression score and serum albumin level.

RESULTS

An analysis of covariance stratified by sex showed that participants with moderate-to-severe depression had significantly decreased total LBM and total and regional %LBM in men, except for total LBM and percentage gynoid LBM, which was observed in women. In the BMI stratified analysis of covariance, depression was significantly associated with decreased total and regional %LBM and with increased total and regional percentage fat body mass. In people with BMI≥25kg/m(2), the associations between depression or depressive syndrome and LBM, and total and regional %LBM are stronger compared to those with BMI<25kg/m(2). Multiple linear regression analysis showed that depression score was significantly negatively associated with serum albumin level.

LIMITATIONS

This is a cross-sectional study based on a general population, some information about clinical diagnosis and medication use is not available.

CONCLUSIONS

Depression had a significant negative association with LBM and serum albumin level.

Gene expression profiles in relation to tension and dissociation in borderline personality disorder

The biological underpinnings of borderline personality disorder (BPD) and its psychopathology including states of aversive tension and dissociation is poorly understood. Our goal was to examine transcriptional changes associated with states of tension or dissociation within individual patients in a pilot study. Dissociation is not only a critical symptom of BPD but has also been associated with higher risk for self-mutilation and depression. We conducted a whole blood gene expression profile analysis using quantitative PCR in 31 female inpatients with BPD. For each individual, two samples were drawn during a state of high tension and dissociation, while two samples were drawn at non-tension states. There was no association between gene expression and tension states. However, we could show that Interleukin-6 was positively correlated to dissociation scores, whereas Guanine nucleotide-binding protein G(s) subunit alpha isoforms, Mitogen-activated protein kinase 3 and 8, Guanine nucleotide-binding protein G(i) subunit alpha-2, Beta-arrestin-1 and 2, and Cyclic AMP-responsive element-binding protein were negatively correlated to dissociation. Our data point to a potential association of dissociation levels with the expression of genes involved in immune system regulation as well as cellular signalling/second-messenger systems. Major limitations of the study are the the possibly heterogeneous cell proportions in whole blood and the heterogeneous medication.

Interconnection between biological abnormalities in borderline personality disorder: use of the Bayesian networks model

There is agreement in that strengthening the sets of neurobiological data would reinforce the diagnostic objectivity of many psychiatric entities. This article attempts to use this approach in borderline personality disorder (BPD). Assuming that most of the biological findings in BPD reflect common underlying pathophysiological processes we hypothesized that most of the data involved in the findings would be statistically interconnected and interdependent, indicating biological consistency for this diagnosis. Prospectively obtained data on scalp and sleep electroencephalography (EEG), clinical neurologic soft signs, the dexamethasone suppression and thyrotropin-releasing hormone stimulation tests of 20 consecutive BPD patients were used to generate a Bayesian network model, an artificial intelligence paradigm that visually illustrates eventual associations (or inter-dependencies) between otherwise seemingly unrelated variables. The Bayesian network model identified relationships among most of the variables. EEG and TSH were the variables that influence most of the others, especially sleep parameters. Neurological soft signs were linked with EEG, TSH, and sleep parameters. The results suggest the possibility of using objective neurobiological variables to strengthen the validity of future diagnostic criteria and nosological characterization of BPD.

Increased psychological and attenuated cortisol and alpha-amylase responses to acute psychosocial stress in female patients with borderline personality disorder

OBJECTIVE

Borderline personality disorder (BPD) is characterized by increased self-reported stress and emotional responding. Knowledge about the psychological and physiological mechanisms that underlie these experiences in BPD patients is scarce. The objective was to assess both psychological and endocrinological responses to a standardized psychosocial stressor in female BPD patients and healthy controls.

METHODS

A total of 15 female BPD patients and 17 healthy control subjects were included in a case-control study. All subjects were free of any medication, had a regular menstrual cycle, and were investigated during the luteal phase of their menstrual cycle. Co-occurring current major depression, current substance abuse/dependence, and lifetime schizophrenia or bipolar I disorder were excluded. Psychological measures of stress, salivary cortisol, salivary alpha-amylase, plasma ACTH, plasma norepinephrine and epinephrine concentrations were measured before, during, and after exposure to a standardized psychosocial stress protocol.

RESULTS

BPD patients displayed maladaptive cognitive appraisal processes regarding the upcoming stressor as well as significantly higher subjective stress, coupled with a substantial cortisol and alpha-amylase hyporeactivity to the stressor in comparison to the controls. No significant differences for ACTH and catecholaminergic responses were observed, while the ACTH:cortisol ratio was higher in BPD patients than in controls.

CONCLUSIONS

Attenuated cortisol responsiveness in BPD patients might in part be explained by decreased adrenal responsiveness to endogenous ACTH and altered central noradrenergic activation as reflected by alpha-amylase.

Borderline personality disorder: hypothalamus pituitary adrenal axis and findings from neuroimaging studies

Borderline personality disorder (BPD) is a complex and serious mental disorder that is commonly seen psychiatric practice. Although stress, especially early life stress, seems to be associated with the development of the disorder, there has been far less research on the function of the hypothalamic-pituitary-adrenal (HPA) axis in BPD, compared to other psychiatric disorders, such as major depressive disorder and post-traumatic stress disorder. Stress has been suggested to exert damaging effects on the brain, particularly the hippocampus; therefore, neuroimaging studies yield important insight into the neurobiology of BPD. This article reviews research on the HPA axis and neuroimaging studies in BPD and aims to integrate these findings.

The hypothalamic-pituitary-adrenal axis in borderline personality disorder: a review

BACKGROUND

borderline personality disorder (BPD) is a psychiatric diagnosis characterized by high exposure, reactivity, and vulnerability to stress. Given these abnormalities in stress reactivity in BPD, there is a question of whether the hypothalamic-pituitary-adrenal (HPA) axis functions normally in BPD, since the activation of the HPA axis normally occurs to coordinate both behavioral and physiologic responses to stress. Several studies have investigated the functioning of the HPA axis in BPD and have shown varied results. This review seeks to summarize and interpret the findings of this growing literature.

METHODS

Pubmed search for English language articles on borderline personality disorder and hypothalamic-pituitary-adrenal axis.

RESULTS

findings are mixed but suggest that important variables relevant to between-group differences include comorbid depression, comorbid posttraumatic stress disorder, dissociative symptoms, and history of childhood abuse.

DISCUSSION

comorbid diagnoses and clinical features such as trauma history and symptom severity may have variable, interacting influences on the psychoneuroendocrine profile in BPD. Also explored here are the implications of these findings for developing possible models of HPA-axis dysfunction in BPD, for identifying potential targets for treatment, and for improving the methodology of future studies.

Pituitary volume in teenagers with first-presentation borderline personality disorder

This study used magnetic resonance imaging to examine pituitary gland volume (PGV) in teenage patients with a first presentation of borderline personality disorder (BPD). No difference in PGV was observed between healthy controls (n=20) and the total BPD cohort (n=20). However, within the BPD cohort, those exposed to childhood trauma (n=9) tended to have smaller pituitaries (-18%) than those with no history of childhood trauma (n=10). These preliminary findings suggest that exposure to childhood trauma, rather than BPD, per se, might be associated with reduced PGV, possibly reflecting hypothalamic-pituitary-adrenal axis dysfunction.

A preliminary study of cortisol and norepinephrine reactivity to psychosocial stress in borderline personality disorder with high and low dissociation

The goal of the current study was to investigate subjective and neurohormonal reactivity to acute psychosocial stress in borderline personality disorder (BPD) as a function of dissociative symptoms. Five BPD subjects with high dissociation, 8 BPD subjects with low dissociation, and 11 healthy control subjects were compared in basal urinary cortisol and norepinephrine, as well as in plasma cortisol and norepinephrine reactivity to the Trier Social Stress Test (TSST). Subjective stress rating and emotional response to the TSST were also measured. The three groups differed significantly in cortisol stress reactivity, with the high-dissociation BPD group demonstrating the most robust response. The three groups did not significantly differ in norepinephrine stress reactivity. In the combined BPD sample, dissociation severity tended to be inversely correlated with basal urinary norepinephrine, was positively correlated with norepinephrine stress reactivity. Childhood trauma was inversely correlated with basal urinary cortisol. In conclusion, despite its small sample size this pilot study suggests that dissociative symptomatology may be a marker of heightened biological vulnerability to stress in BPD, and merits further study.

Cortisol, the cortisol-dehydroepiandrosterone ratio, and pro-inflammatory cytokines in patients with current major depressive disorder comorbid with borderline personality disorder

BACKGROUND

Major depression in young women is often comorbid with borderline personality disorder (BPD); however, adrenal steroids and pro-inflammatory cytokines in patients with comorbid current major depressive disorder and BPD (MDD/BPD) have not been systematically examined. Therefore, our study aimed at examining serum profiles of cortisol, cytokines, and the cortisol/dehydroepiandrosterone (cortisol/DHEA) ratio in MDD/BPD patients and a healthy comparison group.

METHODS

Twelve medication-free female patients with MDD/BPD and 12 healthy women were included. Serum profiles of cortisol, DHEA, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-1beta were sampled, and the molar cortisol/DHEA ratio was determined.

RESULTS

Concentrations of serum cortisol, TNF-alpha, and IL-6, as well as the cortisol/DHEA ratios were significantly increased in MDD/BPD patients as compared with the healthy comparison group.

CONCLUSIONS

Depressed patients with comorbid BPD display endocrine and immune alterations similar to those observed in cases of melancholic MDD without BPD. Elevated concentrations of serum cortisol, cortisol/DHEA ratios, and pro-inflammatory cytokines might indicate a state marker in these patients and might contribute to long-term metabolic alterations that have also been associated with MDD.

Visceral fat deposition and insulin sensitivity in depressed women with and without comorbid borderline personality disorder

OBJECTIVE

Major depressive disorder (MDD) is associated with increased intra-abdominal fat, an important antecedent of noninsulin-dependent diabetes mellitus (NIDDM) and cardiovascular disorders. Furthermore, MDD is commonly accompanied by endocrine and immune dysregulation that has also been discussed in connection with the pathogenesis of NIDDM and ischemic heart disease. In borderline personality disorder (BPD), a dysregulation of the hypothalamic-pituitary-adrenal system has also been described. Therefore, our study aimed at examining visceral fat, insulin resistance, and alterations of cortisol and cytokines in young depressed women with and without comorbid BPD.

METHODS

Visceral fat was measured in 18 premenopausal women with MDD and in 18 women comorbid with MDD and BPD by means of magnetic resonance tomography at the level of the first lumbar vertebral body. Twelve BPD patients without MDD and 20 healthy women served as the comparison groups. Concentrations of fasting cortisol, tumor necrosis factor-alpha, and interleukin-6 were measured, and indicators of insulin resistance and beta-cell sensitivity were calculated according to the homeostasis assessment model.

RESULTS

We found increased visceral fat in women comorbid with MDD and BPD, and to a lesser extent, in women with MDD but without BPD. Insulin sensitivity was reduced in comorbid patients. Serum interleukin-6 (IL-6) and tumor necrosis factor-alpha concentrations were significantly increased in both groups of depressed patients. Reduced insulin sensitivity correlated with the amount of visceral fat and with serum concentrations of IL-6.

CONCLUSION

Young depressed women with and without comorbid BPD display increased visceral fat and may constitute a risk group for the development of NIDDM and the metabolic syndrome. Our data support the hypothesis that the immune and endocrine alterations associated with MDD and BPD may contribute to the pathophysiologic processes associated with NIDDM.

Is the biological nature of depressive symptoms in borderline patients without concomitant Axis I pathology idiosyncratic? Sleep EEG comparison with recurrent brief, major depression and control subjects

The relationship between borderline personality disorder (BPD) and the affective disorders is controversial, and we have previously compared BPD and major depression (MD) with endocrinological measures and sleep electroencephalography (S-EEG). We have also compared BPD, MD and recurrent brief depression (RBD) using endocrine tests. We have proposed that depressive symptoms in BPD might have a biological substrate that is distinct from those in depressive illness without comorbid BPD. BPD has been proposed to overlap with RBD, which has been found to share perturbed biological substrates with MD, but we have not found the same biological pattern in BPD. When endocrinological data in BPD, MD and RBD were compared, we did not find evidence of biological linkage between BPD and RBD. To clarify the biological nature of depressive symptoms in BPD, we examined S-EEG characteristics in BPD, RBD, MD and controls. Among 20 BPD patients, 12 were also diagnosed as having clinical RBD. BPD patients showed differences in sleep continuity and especially in sleep architecture compared with RBD, MD and controls. BPD with or without clinical RBD did not show significant differences in any parameter. BPD with or without clinical RBD had less slow sleep activity not only than MD but also than non-borderline RBD patients. We propose that although BPD patients can have concomitant MD, they often exhibit a specific BPD-associated affective syndrome that is different from both MD and non-borderline RBD in the quality and duration of symptoms and the biological substrate.

Increased diurnal salivary cortisol in women with borderline personality disorder

Borderline personality disorder (BPD) is characterized by a pervasive pattern of instability in affect regulation, impulse control, interpersonal relationships, and self-image. In previous studies, we have used portable mini-computers to assess the severity of recurrent states of aversive emotional distress and dissociation during ambulatory conditions. Here, we used this approach for the assessment of the hypothalamic-pituitary-adrenal (HPA) axis in patients with BPD. We studied 23 unmedicated female patients with BPD and 24 matched healthy controls. Salivary cortisol was collected from all participants during ambulatory conditions in response to reminders provided by portable mini-computers on 3 consecutive days every 2 h for 14 h after awakening. In addition, cortisol in response to awakening was determined in four 15 min intervals on days 1 and 2. After the last collection of cortisol on the second day, 0.5 mg dexamethasone was administered in order to achieve cortisol suppression on day 3 (low-dose dexamethasone suppression test, DST). Patients with BPD displayed significantly higher salivary cortisol levels than healthy controls as demonstrated by higher total cortisol in response to awakening and higher total daily cortisol levels. There were significantly more non-suppressors of cortisol in the low-dose DST in the patient group when compared to the control group. The ambulatory assessment of saliva cortisol is a suitable approach to study basic parameters of the HPA-axis in patients with BPD. Increased adrenal activity and lowered feedback sensitivity of the HPA-axis may characterise BPD. Further studies have to reveal reasons of heightened adrenal activity in these patients.

New developments in the neurobiology of borderline personality disorder

Within the past several years, research on the clinical phenomena and neurobiology of borderline personality disorder has increased substantially. Borderline personality disorder is currently best thought of in terms of dimensions rather than as a categorical disorder. This article reviews the most recent findings on two of the core dimensions--affective dysregulation and impulsivity. Most of the neuropsychologic, physiologic, endocrinologic, and neuroimaging data support the theory that a dual brain pathology, affecting prefrontal and limbic circuits, may underlie this hyperarousal-dyscontrol syndrome.

Recent trends in the pharmacotherapy of personality disorders

This article reviews pharmacologic trials conducted between 2000 and 2003 directed at the treatment of borderline personality disorder, antisocial personality disorder, and schizotypal personality disorder. Atypical antipsychotics, antiepileptics, selective serotonin reuptake inhibitors, omega fatty acids, and opioid antagonists have all been studied in the treatment of borderline personality disorder with positive results. Atypical antipsychotics have been studied in both schizotypal personality disorder and antisocial personality disorder, again with encouraging outcome reports. Implications of personality changes in response to pharmacologic treatment are discussed. Based on the prevalence of these disorders and the burden they cause to afflicted individuals and society, further trials are unequivocally indicated.

Sleep EEG findings in ICD-10 borderline personality disorder in Egypt

BACKGROUND

Previous work has demonstrated that patients with borderline personality disorder show some similarities to patients with major depression, especially regarding their sleep profile. This study aimed at investigating such a hypothesis in an Egyptian sample, considering the possible influence of cultural differences.

METHODS

All night polysomnographic assessments were made for 20 ICD-10 diagnosed borderline patients (without co-morbid depression), in addition to 20 patients with major depression and 20 healthy matched controls.

RESULTS

The two patient groups differed significantly from controls in their sleep profile, especially regarding sleep continuity measures, decreased SWS and REM sleep abnormalities. High similarity was found in EEG sleep profile of the two patient groups, though the changes were more robust in patients with depression.

LIMITATION

The small number of subjects precluded finer analyses of sleep microstructure by depressive symptoms.

CONCLUSIONS

The great similarity in EEG sleep profile between borderline personality disorder patients and patients with major depression suggests a common biological origin for both conditions, with the difference being 'quantitative' rather than 'qualitative'. Our data are all the more compelling in that the presumed personality disturbance in the Egyptian culture manifests neurophysiologically as in the Western world.

Sleep-EEG in borderline patients without concomitant major depression: a comparison with major depressives and normal control subjects

The link between borderline personality disorder (BPD) and the affective disorders remains controversial. The aim of this study was to examine the relationships between BPD and major depression (MD) from the perspective of sleep parameters and to contribute to the characterisation of the sleep-EEG in BPD. We compared 20 off-medication BPD in-patients without co-existing MD with 20 sex- and age-matched MD patients without BPD and 20 sex- and age-matched control subjects. BPD patients had a greater prevalence of drug or alcohol abuse and suicide attempts than MD patients. MD patients had higher scores on the Hamilton Depression Rating Scale (HDRS). Both BPD and MD patients had less total sleep time, more prolonged sleep onset latency, and a greater percentage of wakefulness than control subjects. BPD patients and control subjects had more stage 2 sleep than MD patients. BPD patients had a longer duration of rapid eye movement (REM) sleep, and less stage 3, stage 4 and slow wave sleep than MD patients and control subjects. REM latency did not differentiate the three groups. BPD and MD patients shared sleep-continuity characteristics, but sleep architecture differentiated the two groups. BPD patients with a past history of MD had more wakefulness and less slow wave sleep than BPD patients without a history of MD; other sleep parameters, age, sex and HDRS scores were not statistically different in the two BPD subgroups. Although BPD and MD may coexist, the present study offers more arguments favouring the concept that they are not biologically linked and that BPD patients with depressive symptoms often experience an affective syndrome different from that in MD patients without BPD, in terms of quality and duration of symptoms and of the biological substrate.

Neuropsychological functioning in patients with borderline personality disorder

Although results have been variable, studies suggest that individuals with borderline personality disorder (BPD) exhibit cognitive deficits suggestive of frontal- and temporal-lobe dysfunction. Patients diagnosed with BPD (n = 18) using two structured interviews, and who were carefully screened for neurological and substance-use disorders, were compared to depressed patients (n = 18) and a nonpsychiatric control group (n = 18) on a series of neuropsychological tasks. The role of emotion on cognitive functioning was assessed by including emotional stimuli and interference on several of the tasks. Little support was found for the neurobehavioral hypothesis of BPD. The BPD group performance did not differ from the normal group on most tasks of executive functioning or memory, and the introduction of emotional stimuli did not impair performance. The depressed group performed less effectively than the other groups. Reasons for variable findings and factors affecting the cognitive functioning of patients with BPD are discussed. There may be considerable heterogeneity in the cognitive functioning of BPD patients, with those exhibiting significant cognitive deficits comprising only a subgroup.

Relationship between depression and borderline personality disorder

The frequent occurrence of depressive symptoms in patients with borderline personality disorder has generated considerable interest in the nature of the relationship between borderline personality disorder and the depressive disorders. Data from the perspectives of phenomenology, biology, family history, course of illness, comorbidity patterns, and treatment response have been brought to bear on the question. Reviews based on research available by 1985 and 1991, respectively, arrived at differing conclusions: (1) that both disorders shared common but non-specific sources, and (2) that the two disorders were unrelated but co-occurred because of the high prevalence of each. Since the time of these reviews, additional evidence has become available from a wider range of biological investigations, better controlled comorbidity studies, studies of the relationship of psychosocial stressors to the course of each disorder and neuroimaging studies. In reviewing the more recent findings, we propose the less parsimonious hypothesis that the disorders co-occur, both because they share some common biological features and because the psychosocial sequella of each can contribute to the development of the other.