The Extrapyramidal Symptom Rating Scale and Its Abbreviated Version: A Critical Review of Clinimetric Properties

BACKGROUND

The Extrapyramidal Symptom Rating Scale - Abbreviated (ESRS-A) is an abbreviated version of the Extrapyramidal Symptom Rating Scale (ESRS) with instructions, definitions, and a semi-structured interview that follows clinimetric concepts of measuring clinical symptoms. Similar to the ESRS, the ESRS-A was developed to assess four types of drug-induced movement disorders (DIMD): parkinsonism, akathisia, dystonia, and tardive dyskinesia (TD).

SUMMARY

The present review of the literature provides the most relevant clinimetric properties displayed by the ESRS and ESRS-A in clinical studies. Comprehensive ESRS-A definitions, official scale, and basic instructions are provided. ESRS inter-rater reliability was evaluated in two pivotal studies and in multicenter international studies. Inter-rater reliability was high for assessing both antipsychotic-induced movement disorders and idiopathic Parkinson's disease. Guidelines were also established for inter-rater reliability and the rater certification processes. The ESRS showed good concurrent validity with 96% agreement between Abnormal Involuntary Movement Scale (AIMS) for TD-defined cases and ESRS-defined cases. Similarly, concurrent validity for ESRS-A total and subscores for parkinsonism, akathisia, dystonia, and dyskinesia ranged from good to very good. The ESRS was particularly sensitive for detecting DIMD-related movement differences following treatment with placebo, antipsychotics, and antiparkinsonian and antidyskinetic medications. ESRS measurement of drug-induced extrapyramidal symptoms was shown to discriminate extrapyramidal symptoms from psychiatric symptoms.

KEY MESSAGES

The ESRS and ESRS-A are valid clinimetric indices for measuring DIMD. They can be valuably implemented in clinical research, particularly in trials testing antipsychotic medications, and in clinics to detect the presence, severity, and response to treatment of movement disorders.

Test-retest reliability of the Childhood Trauma Questionnaire in psychotic disorders

BACKGROUND

Childhood trauma is common and associated with worse psychiatric outcomes. Yet, clinicians may not inquire about childhood trauma due to a misconception that patients cannot provide reliable reports. The goal of this study was to examine the reliability of self-reports of childhood trauma in psychotic disorders.

METHODS

We examined the test-retest reliability of the Childhood Trauma Questionnaire (CTQ) in schizophrenia (SZ, n = 19), psychotic bipolar disorder (BD, n = 17), and healthy control (HC, n = 28) participants who completed the CTQ on ≥2 occasions over variable time periods (mean 19.6 months). We calculated the intraclass correlation (ICC) for the total CTQ score, each of the five CTQ domains, and the minimization/denial subscale for the three groups. For any CTQ domains showing low test-retest reliability (ICC < 0.61), we also explored whether positive, negative, depressive, and manic symptom severity were associated with CTQ variability.

RESULTS

We found high ICC values for the total CTQ score in all three groups (SZ 0.82, BD 0.85, HC 0.88). The ICC values for CTQ subdomains were also high with the exceptions of scores for sexual abuse in BD (0.40), emotional neglect in SZ (0.60), and physical neglect in BD (0.51) and HC (0.43). In exploratory analyses, self-reports of sexual abuse in BD were associated with greater severity of depressive symptoms (β = 0.108, p = 0.004).

CONCLUSIONS

Patients with SZ and BD can provide reliable self-reports of childhood trauma, especially related to physical and emotional abuse. The presence of psychosis should not deter clinicians from asking patients about childhood trauma.

Abnormal Brain Bioenergetics in First-Episode Psychosis

BACKGROUND

Converging evidence indicates impaired brain energy metabolism in schizophrenia and other psychotic disorders. Creatine kinase (CK) is pivotal in providing adenosine triphosphate in the cell and maintaining its levels when energy demand is increased. However, the activity of CK has not been investigated in patients with first-episode schizophrenia spectrum disorders.

METHODS

Using in vivo phosphorus magnetization transfer spectroscopy, we measured CK first-order forward rate constant (k f ) in the frontal lobe, in patients with first-episode psychosis (FEP; n = 16) and healthy controls (n = 34), at rest.

RESULTS

CK k f was significantly reduced in FEP compared to healthy controls. There were no differences in other energy metabolism-related measures, including phosphocreatine (PCr) or ATP, between groups. We also found increase in glycerol-3-phosphorylcholine, a putative membrane breakdown product, in patients.

CONCLUSIONS

The results of this study indicate that brain bioenergetic abnormalities are already present early in the course of schizophrenia spectrum disorders. Future research is needed to identify the relationship of reduced CK k f with psychotic symptoms and to test treatment alternatives targeting this pathway. Increased glycerol-3-phosphorylcholine is consistent with earlier studies in medication-naïve patients and later studies in first-episode schizophrenia, and suggest enhanced synaptic pruning.

White Matter Measures and Cognition in Schizophrenia

White matter (WM) abnormalities are commonly reported in schizophrenia but whether these arise from the axon or myelin compartments or both is not known. In addition, the relationship between WM abnormalities and cognitive function is not fully explored in this condition. We recruited 39 individuals with schizophrenia spectrum disorders and 37 healthy comparison subjects. All participants underwent MRI scanning at 4 Tesla to collect data in the prefrontal white matter on magnetization transfer ratio (MTR) and diffusion tensor spectroscopy (DTS) which provide information on myelin and axon compartments, respectively. We also collected Matrics Composite Cognitive Battery (MCCB) and Stroop cognitive data. We found an elevated N-acetylaspartate (NAA) apparent diffusion coefficient in schizophrenia in this cohort as in our previous work; we also observed poorer performance on both the MCCB composite and the Stroop in schizophrenia patients compared to controls. The MTR measure was correlated with the MCCB composite (r = 0.363, p = 0.032) and Stroop scores (r = 0.387, p = 0.029) in healthy individuals but not in schizophrenia. Since this is the first exploration of the relationship between these WM and cognitive measures, we consider our analyses exploratory and did not adjust for multiple comparisons; the findings are not statistically significant if adjusted for multiple comparisons. These findings indicate that WM integrity is associated with cognitive function in healthy individuals but this relationship breaks down in patients with schizophrenia.

Abnormalities in High-Energy Phosphate Metabolism in First-Episode Bipolar Disorder Measured Using 31P-Magnetic Resonance Spectroscopy

BACKGROUND

Brain energy metabolism is critical for supporting synaptic function and information processing. A growing body of evidence suggests abnormalities in brain bioenergetics in psychiatric disorders, including both bipolar disorder (BD) and schizophrenia. ³¹P magnetic resonance spectroscopy provides a noninvasive window into these processes in vivo. Using this approach, we previously showed that patients with BD show normal adenosine triphosphate (ATP) and phosphocreatine levels at rest but cannot maintain normal ATP levels in the visual cortex during times of high energy demand (photic stimulation). Because ATP is replenished from phosphocreatine via the creatine kinase reaction, we have now measured the creatine kinase forward reaction rate constant in BD.

METHODS

We studied 20 patients experiencing a first episode of BD and 28 healthy control participants at 4T and quantified creatine kinase forward reaction rate constant using ³¹P magnetization transfer magnetic resonance spectroscopy as described previously.

RESULTS

We found a significant reduction in creatine kinase forward reaction rate constant in the BD group (F = 4.692, p = .036), whereas brain ATP and phosphocreatine concentrations, as well as brain parenchymal pH, were normal.

CONCLUSIONS

These results pinpoint a specific molecular mechanism underlying our previous observation of an inability to replenish brain ATP during times of high energy demand in BD.

The Diagnostic clinical Interview for Drug Withdrawal 1 (DID-W1) – New Symptoms of Selective Serotonin Reuptake Inhibitors (SSRI) or Serotonin Norepinephrine Reuptake Inhibitors (SNRI): inter-rater reliability

Aim

A wide range of clinical phenomena have been reported with dose reduction or drug discontinuation of Selective Serotonin Reuptake Inhibitors (SSRIs) or Serotonin Norepinephrine Reuptake Inhibitors (SNRIs). In 2015, a new classification of SRIs/SNRIs withdrawal (i.e., new withdrawal symptoms, rebound symptoms withdrawal, persistent post-withdrawal disorders) was outlined on the basis of the literature and clinical observations. A semistructured clinical interview, the Diagnostic clinical Interview for Drug Withdrawal 1 - New Symptoms of SSRI and SNRI (DID-W1), was developed for identifying and differentiating such syndromes. Its inter-rater reliability has been tested.

Methods

Seventeen consecutive outpatients with a history of SSRI or SNRI dose reduction or discontinuation were assessed independently by 2 clinicians at different times during the same day. Percent agreement, Cohen’s kappa, and the squared correlation coefficient were used to measure inter-rater reliability.

Results

The percent agreement for the whole interview was 97.06%, the Cohen’s kappa 0.85 (95% CI of 0.61-1.08), the squared correlation coefficient 0.72.

Discussion and conclusions

The kappa values indicated excellent inter-rater agreement. Validity evaluation and comparison with other instruments need to be performed. The DID-W1 may help diagnosing the clinical phenomena related to SSRI and SNRI discontinuation, their differentiation from relapse, and the potential iatrogenic origin of psychiatric symptoms in clinical practice.

Brain lactate and pH in schizophrenia and bipolar disorder: a systematic review of findings from magnetic resonance studies

Converging evidence from molecular to neuroimaging studies suggests brain energy metabolism abnormalities in both schizophrenia and bipolar disorder. One emerging hypothesis is: decreased oxidative phosphorylation leading to accumulation of lactic acid from glycolysis and subsequent acidification of tissue. In this regard, integrating lactate and pH data from magnetic resonance spectroscopy (MRS) studies in both diseases may help us understand underlying neurobiological mechanisms. In order to achieve this goal, we performed a systematic search of case-control studies examining brain lactate or pH among schizophrenia and/or bipolar patients by using MRS. Medline/Pubmed and EBSCO databases were searched separately for both diseases and outcomes. Our search yielded 33 studies in total composed of 7 lactate and 26 pH studies. In bipolar disorder, 5 out of 6 studies have found elevated lactate levels especially in the cingulate cortex and 4 out of 13 studies reported reduced pH in the frontal lobe. In contrast, in schizophrenia a single study has examined lactate and reported elevation, while only 2 out of 13 studies examining pH have reported reduction in this measure. There were no consistent patterns for the relationship between lactate or pH levels and medication use, disease type, mood state, and other clinical variables. We highlight the need for future studies combining 1H-MRS and 31P-MRS approaches, using longitudinal designs to examine lactate and pH in disease progression across both schizophrenia and bipolar disorders.

Antipsychotic-Induced Dopamine Supersensitivity Psychosis: Pharmacology, Criteria, and Therapy

The first-line treatment for psychotic disorders remains antipsychotic drugs with receptor antagonist properties at D2-like dopamine receptors. However, long-term administration of antipsychotics can upregulate D2 receptors and produce receptor supersensitivity manifested by behavioral supersensitivity to dopamine stimulation in animals, and movement disorders and supersensitivity psychosis (SP) in patients. Antipsychotic-induced SP was first described as the emergence of psychotic symptoms with tardive dyskinesia (TD) and a fall in prolactin levels following drug discontinuation. In the era of first-generation antipsychotics, 4 clinical features characterized drug-induced SP: rapid relapse after drug discontinuation/dose reduction/switch of antipsychotics, tolerance to previously observed therapeutic effects, co-occurring TD, and psychotic exacerbation by life stressors. We review 3 recent studies on the prevalence rates of SP, and the link to treatment resistance and psychotic relapse in the era of second-generation antipsychotics (risperidone, paliperidone, perospirone, and long-acting injectable risperidone, olanzapine, quetiapine, and aripiprazole). These studies show that the prevalence rates of SP remain high in schizophrenia (30%) and higher (70%) in treatment-resistant schizophrenia. We then present neurobehavioral findings on antipsychotic-induced supersensitivity to dopamine from animal studies. Next, we propose criteria for SP, which describe psychotic symptoms and co-occurring movement disorders more precisely. Detection of mild/borderline drug-induced movement disorders permits early recognition of overblockade of D2 receptors, responsible for SP and TD. Finally, we describe 3 antipsychotic withdrawal syndromes, similar to those seen with other CNS drugs, and we propose approaches to treat, potentially prevent, or temporarily manage SP.

Brain bioenergetics and redox state measured by 31P magnetic resonance spectroscopy in unaffected siblings of patients with psychotic disorders

BACKGROUND

Brain bioenergetic anomalies and redox dysregulation have been implicated in the pathophysiology of psychotic disorders. The present study examined brain energy-related metabolites and the balance between nicotinamide adenine dinucleotide metabolites (oxidized NAD+ and reduced NADH) using ³¹P-magnetic resonance spectroscopy (³¹P-MRS) in unaffected siblings, compared to first episode psychosis (FEP) patients and healthy controls.

METHODS

21 unaffected siblings, 32 FEP patients (including schizophrenia spectrum and affective psychoses), and 21 controls underwent ³¹P-MRS in the frontal lobe (6×6×4cm³) on a 4T MR scanner, using custom-designed dual-tuned surface coil with outer volume suppression. Brain parenchymal pH and steady-state metabolite ratios of high energy phosphate compounds were measured. NAD+ and NADH levels were determined using a ³¹P-MRS fitting algorithm. 13 unaffected sibling-patient pairs were related; other patients and siblings were unrelated. ANCOVA analyses were used to examine ³¹P-MRS measures, with age and gender as covariates.

RESULTS

The phosphocreatine/adenosine triphosphate ratio was significantly reduced in both unaffected siblings and FEP patients, compared to controls. NAD+/NADH ratio was significantly reduced in patients compared to siblings and controls, with siblings showing a reduction in NAD+/NADH compared to controls that was not statistically significant. Compared to patients and controls, siblings showed significantly reduced levels of NAD+. Siblings did not differ from patients or controls on brain pH.

DISCUSSION

Our results indicate that unaffected siblings show some, but not all the same abnormalities in brain energy metabolites and redox state as FEP patients. Thus, ³¹P-MRS studies may identify factors related both to risk and expression of psychosis.

McLean OnTrack: a transdiagnostic program for early intervention in first-episode psychosis

AIMS

Most programs specializing in the treatment of first-episode psychosis in the United States focus on schizophrenia. However, many early psychosis patients do not fit into this diagnostic category. Here we describe McLean OnTrack, an intensive outpatient treatment program that accepts all comers with first-episode psychosis.

METHODS

We assessed baseline characteristics of patients in the 2.5 years since program initiation. We examined how initial referral diagnoses compare with current diagnoses, calculating the proportion of diagnostic changes.

RESULTS

At 2.5 years, patients in McLean OnTrack consist of 30 (33.0%) individuals with primary psychotic disorder, 40 (44.0%) with affective psychosis, 19 (20.9%) with psychotic disorder not otherwise specified (NOS) who do not meet full criteria for either category and two (2.2%) individuals with no psychosis. Although patients with affective psychosis had higher pre-morbid functioning, all three categories of psychosis had similar rates of prior hospitalizations and substance use. The retention rate in the psychotic disorder NOS group was lower than that in affective and primary psychotic disorders. Finally, diagnoses changed over the course of treatment in 50.5% of patients.

CONCLUSIONS

Diagnostic heterogeneity appears to be the norm among patients with first-episode psychosis, and diagnoses commonly evolve over the illness course. Baseline indices of illness severity were similar across categories and suggest the need for early intervention, irrespective of specific diagnosis. We discuss the benefits and challenges of a transdiagnostic approach to early intervention in first-episode psychosis, treating patients who share many but not all characteristics.

Factors associated with overweight and obesity in schizophrenia, schizoaffective and bipolar disorders

Evidence suggests abnormal bioenergetic status throughout the body in psychotic disorders. The present study examined predictors of elevated body mass index (BMI) across diagnostic categories of schizophrenia, schizoaffective and bipolar disorders. In a cross-sectional study, we studied demographic and clinical risk factors for overweight and obesity in a well-characterized sample of 262 inpatients and outpatients with schizophrenia (n=59), schizoaffective disorder (n=81) and bipolar I disorder (n=122). Across the three diagnostic categories, the prevalence of overweight (29.4%) and obesity (33.2%) combined was 62.6% (164/262). Logistic regression analyses, adjusted for age, sex and ethnicity, showed that schizoaffective disorder, lifetime major depressive episode, presence of prior suicide attempt, and more than 5 lifetime hospitalizations were significantly associated with BMI≥25. Patients with schizophrenia had significantly lower risk for overweight and obesity. Overall, we found that affective components of illness were associated with elevated BMI in our cross-diagnostic sample. Our results show that patients with schizoaffective disorder have a greater risk for obesity. Identifying predictors of elevated BMI in patients with psychotic and mood disorders will help prevent obesity and related cardiovascular and cerebral complications. Future studies are needed to elucidate the mechanistic nature of the relationship between obesity and psychiatric illness.

Diffusion tensor imaging in first degree relatives of schizophrenia and bipolar disorder patients

OBJECTIVES

White matter (WM) abnormalities are one of the most widely and consistently reported findings in schizophrenia (SZ) and bipolar disorder (BD). If these abnormalities are inherited determinants of illness, suitable to be classified as an endophenotype, relatives of patients must also have them at higher rate compared to the general population. In this review, we evaluate published diffusion tensor imaging (DTI) studies comparing first degree relatives of SZ and BD patients and healthy control subjects.

METHODS

We searched PubMed, Embase and PsychInfo for DTI studies which included an unaffected relative and a healthy comparison group.

RESULTS

22 studies fulfilled the inclusion criteria. WM abnormalities were found in many diverse regions in relatives of SZ patients. Although the findings were not completely consistent across studies, the most implicated areas were the frontal and temporal WM regions and the corpus callosum. Studies in relatives of BD patients were fewer in number with less consistent findings reported across studies.

CONCLUSIONS

Our review supports the concept of WM abnormalities as an endophenotype in SZ, with somewhat weaker evidence in BD, but larger and higher quality studies are needed to make a definitive comment.

Cognitive impairment in systemic lupus erythematosus women with elevated autoantibodies and normal single photon emission computerized tomography

BACKGROUND

Systemic lupus erythematosus (SLE) is known to induce psychiatric disorders, from psychoses to maladaptive coping. Brain autoantibodies were proposed to explain SLE neuropsychiatric disorders and found to be elevated before the onset of clinical symptoms. We assessed cognition in Caucasian SLE women with elevated autoantibodies without overt neuropsychiatric syndromes, in conjunction with single photon emission computerized tomography (SPECT).

METHODS

31 women meeting SLE criteria of the American College of Rheumatology (ACR) were included. Patients who met the ACR neuropsychiatric definition were excluded. Matched controls were 23 healthy women from the Champagne-Ardenne region, France. Participants completed neuropsychological and autoantibodies measurements, and 19 completed SPECT.

RESULTS

61% (19/31) of women with SLE and 53% (9/17) of those with normal SPECT had significant global cognitive impairment defined as 4 T-scores <40 in cognitive tests, compared to 0% (0/23) of controls. SLE women also had significantly greater cognitive dysfunction (mean T-score) on the Wechsler Adult Intelligence Scale (WAIS) visual backspan, Trail Making Test A and B, WAIS Digit Symbol Substitution Test and Stroop Interference, compared to controls. Elevated antinuclear antibody correlated with impairment in the WAIS visual span, WAIS visual backspan, and cancellation task; elevated anti-double-stranded DNA antibody and anticardiolipin correlated respectively with impairment in the Trail Making Test A and WAIS auditive backspan. Two SLE women had abnormal SPECT.

CONCLUSIONS

A high prevalence of cognitive deficits was found in Caucasian SLE women compared to normal women, which included impairment in cognitive domains important for daily activities. Elevated autoantibodies tended to correlate with cognitive dysfunction.

Concomitant use of simvastatin and amiodarone resulting in severe rhabdomyolysis: a case report and review of the literature

Myopathy, including rhabdomyolysis, is a well-known, albeit rare complication of statin therapy. Predisposing factors include comorbidities and the concomitant use of cytochrome P-450 (CYP) 3A4 inhibitors. We report a case of severe simvastatin-induced rhabdomyolysis triggered by the addition of amiodarone to previously well-tolerated chronic statin therapy. Physicians should be aware of the risk of this potentially severe drug interaction. The dose of simvastatin should be reduced (to 20 mg daily) when concomitant treatment with amiodarone is required, or preference should be given to pravastatin, rosuvastatin or fluvastatin, which are not metabolised by the CYP 3A4.

Chyloma: an uncommon cause of supraclavicular swelling

We report the case of a 46-year-old woman who noticed a swelling of the left supraclavicular fossa of rapid onset soon after a Mycoplasma Pneumoniae upper respiratory infection. On the basis of clinical history, physical examination and imaging findings, a diagnosis of chyloma due to intense non-productive coughing bouts was made. The supraclavicular swelling progressively disappeared after a few days. This observation prompted us to briefly review the pathophysiology of chylomas.

Is DSM-IV bereavement exclusion for major depressive episode relevant to severity and pattern of symptoms? A case-control, cross-sectional study

OBJECTIVE

To assess the DSM-IV major depressive episode (MDE) bereavement exclusion criterion by comparing severity and pattern of symptoms in bereavement-excluded individuals satisfying all other DSM-IV MDE criteria to these same variables in MDE controls.

METHOD

A case-control, cross-sectional study of self-referred individuals seeking treatment for depressive symptoms was conducted. A total of 17,988 subjects met DSM-IV MDE symptom criteria. Of these, 1,521 individuals (8.5%) met all MDE criteria except the bereavement exclusion. They were matched by age, gender, marital status, and educational level with 1,521 MDE controls. Among the MDE controls, 292 had a recent bereavement and 1,229 did not. Severity of depression was measured by the number of MDE symptoms and the Montgomery-Asberg Depression Rating Scale (MADRS) score. Symptom cues of the bereavement-exclusion criterion were analyzed. The study was conducted between September 2003 and May 2004.

RESULTS

Bereavement-excluded subjects were more severely depressed than MDE controls without bereavement and similar to MDE controls with bereavement. Two symptom cues, suicidal ideation and worthlessness, and the majority of other depressive symptoms were more pronounced in bereavement-excluded individuals than in MDE controls.

CONCLUSIONS

Symptom cues of the DSM-IV MDE bereavement exclusion criterion should be modified since they could result in patients failing to be correctly diagnosed and treated.

Normal and pathological aging of attention in presymptomatic Huntington's, Huntington's and Alzheimer's Disease, and nondemented elderly subjects

BACKGROUND

Attention models view attention as having at least two components: endogenous attention defined as executive and directed by voluntary acts, and exogenous attention defined as automatic and directed by external stimulation.

METHODS

Three studies (2 of our own) were designed to evaluate the decline of these two components of attention in normal aging and two neurodegenerative diseases. Standardized tests derived from Posner's model of visuospatial attention were administered to normal healthy elderly participants (n = 13), patients suffering from Huntington's disease (HD; n = 17) and Alzheimer's disease (n = 15), and matched control subjects (n = 57). Outcome measures were reaction time (RT) and RT difference score (defined as invalid RT minus valid RT).

RESULTS

In healthy elderly participants, the decline was more pronounced for endogenous attention in situations of perceptual conflict. In Alzheimer's disease, there was a significant decline in both attention components, while in HD, voluntary attention was markedly impaired and automatic attention preserved.

CONCLUSIONS

Normal aging and HD are characterized by decreased endogenous attention in situations of perceptual conflict. Our data support previous findings that older people display impairment of attention in complex perceptual situations. We propose a model which allows for the separation of attention pathologies, thus improving therapeutic strategies for patients and elderly.

Absence of gender effects on attention deficit hyperactivity disorder: findings in nonreferred subjects

OBJECTIVE

In a previous study, the authors found that, compared with referred boys with attention deficit hyperactivity disorder (ADHD), girls are less likely to manifest comorbid disruptive behavior disorders and learning disabilities--characteristics that could adversely affect identification of ADHD in girls. However, because referral bias can affect outcome, these findings require replication in nonreferred groups of ADHD subjects.

METHOD

The authors evaluated gender effects in a large group of nonreferred siblings (N=577) of probands with ADHD and non-ADHD comparison subjects. Ninety-eight of the nonreferred siblings (N=73 males, N=25 females) met the criteria for diagnosis of ADHD, and 479 (N=244 males, N=235 females) did not meet those criteria. All siblings were systematically and comprehensively assessed with measures of emotional, school, intellectual, interpersonal, and family functioning. The assessment battery used for the siblings was the same as that used for the probands.

RESULTS

The nonreferred males and females with ADHD did not differ in DSM-IV subtypes of ADHD, psychiatric comorbidity, or treatment history. They also showed similar levels of cognitive, psychosocial, school, and family functioning.

CONCLUSIONS

These findings suggest that the clinical correlates of ADHD are not influenced by gender and that gender differences reported in groups of subjects seen in clinical settings may be caused by referral biases.

Attention-deficit/hyperactivity disorder endophenotypes

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable disorder with a multifactorial pattern of inheritance. For complex conditions such as this, biologically based phenotypes that lie in the pathway from genes to behavior may provide a more powerful target for molecular genetic studies than the disorder as a whole. Although their use in ADHD is relatively new, such "endophenotypes" have aided the clarification of the etiology and pathophysiology of several other conditions in medicine and psychiatry. In this article, we review existing data on potential endophenotypes for ADHD, emphasizing neuropsychological deficits because assessment tools are cost effective and relatively easy to implement. Neuropsychological impairments, as well as measures from neuroimaging and electrophysiological paradigms, show correlations with ADHD and evidence of heritability, but the familial or genetic overlap between these constructs and ADHD remains unclear. We conclude that these endophenotypes will not be a quick fix for the field but offer potential if careful consideration is given to issues of heterogeneity, measurement and statistical power.

Dopaminergic neurotransmission and restless legs syndrome: a genetic association analysis

In order to examine the genetic substrate of the dopamine hypothesis in restless legs syndrome, we analyzed eight genes coding for receptors and enzymes related to dopaminergic transmission, using a population of 92 patients with restless legs syndrome and 182 controls matched for ethnic background. No significant differences were found in the genotypic or allelic distributions between groups. Furthermore, no effect of the loci examined was observed with stratification using clinical parameters such as age at onset or periodic leg movements during sleep index.