Profiles and cognitive predictors of motor functions among early school-age children with mild intellectual disabilities

BACKGROUND

The purpose of the study was to describe sensorimotor profile in children with mild intellectual disability (ID), and to examine the association between cognitive and motor function.

METHODS

A total of 233 children with mild ID aged 7 to 8 years were evaluated with measures of cognitive, motor and sensory integrative functioning.

RESULTS

Children with mild ID performed significantly less well on all test measures. 44.2% of children scored in the impaired range on seven out of 22 sensorimotor measures. They had weaker fine motor skills than gross motor skills. Sensory integrative functions were only mildly impaired. Total IQ substantially predicted overall performance on each motor test. Specifically, verbal comprehension and processing speed indexes were significant predictors of gross and fine motor function.

CONCLUSIONS

Sensorimotor dysfunctions were found to be very frequent in children with mild ID. Early identification of sensorimotor impairments is essential to prompt early intervention and facilitate better integration into regular school settings.

Characterizing major depression phenotypes by presence and type of psychomotor disturbance in adolescents and young adults

Major depressive disorder (MDD) is phenomenologically heterogeneous, which has prompted investigation of intermediate MDD phenotypes based on specific key symptoms. Presence and type of psychomotor disturbance may be an important psychopathologic feature that differentiates clinically distinct forms of juvenile MDD. This study examined the phenotypic status of three putative MDD phenotypes in a community sample of 941 youths: (1) agitated depression (MDD with psychomotor agitation), (2) retarded depression (MDD with psychomotor retardation), and (3) agitated-retarded depression (MDD with psychomotor agitation and retardation within an episode). Hasler et al.'s [2004: Neuropsychopharmacology 29:1765-1781] criteria of specificity (degree of association with relevant symptoms and conditions related to the disease of interest versus other psychiatric conditions), stability (degree of stability over time), and heritability (degree of familial aggregation with relevant conditions) were used to evaluate the phenotypic significance of these subtypes. Results were suggestive that agitated depression was a relatively specific phenotypic syndrome characterized by irritability, arousal, physical complaints, and vulnerability to anxiety disorders and alcohol dependence; low stability across depressive episodes; and low heritability. Agitated-retarded depression was relatively specific and characterized by increased severity, recurrence, vegetative symptoms, suicidal ideation, social impairment, endogeneity, and vulnerability to anxiety disorders and bulimia; low stability across episodes; and modest heritability. Although retarded depression was associated with some specific distinguishing characteristics, most associations were explained by the increased severity of this phenotype. Retarded depression evidenced little stability or heritability. These findings offer partial support of the phenotypic status of agitated and agitated-retarded depression in youths.

Neurological abnormalities and cognitive ability in first-episode psychosis

BACKGROUND

It remains unclear if the excess of neurological soft signs, or of certain types of neurological soft signs, is common to all psychoses, and whether this excess is simply an epiphenomenon of the lower general cognitive ability present in psychosis.

AIMS

To investigate whether an excess of neurological soft signs is independent of diagnosis (schizophrenia v. affective psychosis) and cognitive ability (IQ).

METHOD

Evaluation of types of neurological soft signs in a prospective cohort of all individuals presenting with psychoses over 2 years (n=310), and in a control group from the general population (n=239).

RESULTS

Primary (P<0.001), motor coordination (P<0.001), and motor sequencing (P<0.001) sign scores were significantly higher in people with any psychosis than in the control group. However, only primary and motor coordination scores remained higher when individuals with psychosis and controls were matched for premorbid and current IQ.

CONCLUSIONS

Higher rates of primary and motor coordination signs are not associated with lower cognitive ability, and are specific to the presence of psychosis.

Task-specific craniocervical dystonia

The pathophysiology of dystonia is incompletely understood. Unlike many other focal dystonias, cervical dystonia, a frequent dystonia leading to twisting of the head, does not appear to be related to overuse or acquisition of a demanding motor skill. Here, we report development of task-specific dystonia of the neck muscles in a 67-year-old patient following bilateral traumatic arm amputation at the age of 15. To compensate for the amputation, the patient learned to write with a pen held in his mouth. After several years of practicing this unusual and demanding skill, symptoms of task-specific cervical dystonia (CD) developed. This dystonia later became permanent, and independent of the motor activity that initially triggered the dystonic muscular contractions. This singular case raises the possibility that the pathophysiology of CD may share common elements with that of focal dystonias in different body regions.

Prenatal risk factors for intraventricular hemorrhage, neonatal death and impaired psychomotor development in very low birth weight infants

AIM

The aim of this study was to determine the relationship between preterm risk factors and neonatal death, cerebral hemorrhage and psychomotor development in very low birth weight infants.

METHODS

A retrospective analysis based on a multivariate logistic regression model was conducted on 253 VLBW infants. Cerebral hemorrhage was assessed by cerebral ultrasound screening within 24 hours of life, psychomotor development by Bailey Psychomotor and Development Index test.

RESULTS

Pre-eclampsia and elective cesarean section (CS) are statistically protective factors in the prevention of cerebral hemorrhage; gestational age is a protective factor for neonatal death; whereas, multiple pregnancy, symmetrically small for gestational-age infants, asphyxia at birth, altered cardiotocography, and cerebral hemorrhage are risk factors for neonatal death; emergency CS and gestational age are protective factors for problems in psychomotor development. The number of fetuses and cerebral hemorrhage are risk factors for impaired psychomotor development at 2 years of age.

CONCLUSION

The great number of obstetrical variables related to neonatal outcome makes it difficult to identify the really important steps, in obstetric management, to prevent long term sequelae. The main risk factors related to psychomotor development still remain gestational age and multiple pregnancy.

Early neurologic assessment in preterm-infants: integration of traditional neurologic examination and observation of general movements

OBJECTIVE

To evaluate the possible additional benefit in terms of prognostic accuracy of an integrated application of a traditional scorable method of neurologic examination and the Prechtl's method of qualitative assessment of general movements (GMs) in a large population of 903 consecutive preterm infants.

STUDY DESIGN

Infants were enrolled from the Intensive Care Unit of the University of Catania. Inclusion criteria were a gestational age below 37 weeks and the absence of genetic disorders. All infants underwent serial ultrasound and at 3 months performed both the GMs assessment and the Hammersmith Infant Neurologic Examination (HINE). Outcome was assessed at 2 years by the Touwen neurologic examination and the Clinical Adaptive Test/Clinical, Linguistic and Auditory Milestone Scale.

RESULTS

The integration of the two methods was shown to be more effective than the single assessments in predicting neurologic outcome. The additional benefit of combining the two approaches was particularly clear for the discrimination between unilateral and bilateral cerebral palsy.

CONCLUSIONS

The integrated use of a scorable neurological examination and Prechtl's assessment of GMs can improve early prediction of neurodevelopmental outcome in preterm infants and should complement other clinical and instrumental exams in follow-up programs.

[Structural features of perinatal risk factors and their complications contributing to the development of psychomotor delay]

The incidence of perinatal problems in infants might be the one of the main reasons in delayed psychomotor development. The most predictive for future delay in psychomotor development are the pathology of pregnancy and delivery, an intra-uterine infection, incomplete pregnancy and the hypoxic--ischemic injury of the brain. Adequate conduct of the perinatal period, definition of existing or expected problems and preventive measures allows avoiding or reducing pathological conditions and possible future consequences. The goal of the investigation was to determine the structural features of perinatal risk factors contributing to the future delay in psychomotor development. 348 newborns during 24 months have been examined. It was concluded that perinatal risk factors contribute in the structure of future delay of psychomotor development significantly. Early revealing and adequate conducting of the perinatal period, definition of existing or expected problems and adequate measures allows to avoid or reduce possible pathological conditions, their complications and their consequences.

Does catatonia influence the phenomenology of childhood onset schizophrenia beyond motor symptoms?

Childhood onset schizophrenia (COS) and catatonia (C) are rare and severe psychiatric disorders. The aim of this study was to compare the phenomenology of COS with and without catatonia. We examined 33 cases consecutively referred to two major public university hospitals in Paris. There were 18 cases of COS (age=15.9+/-0.8 years) and 15 of COS+C (age=15.4+/-1.4 years). Patients were referred over the course of 3 and 9 years, respectively. Psychiatric assessment included socio-demographic, clinical and psychometric variables: the Brief Psychiatric Rating Scale (BPRS), the Scales for the Assessment of Positive (SAPS) and Negative Symptoms (SANS), and a catatonia rating scale. Patients with COS+C appeared to be more severely ill at admission and discharge compared with COS in nearly all clinical scores. They also exhibited significantly longer episode duration (50.8 weeks+/-4.8 vs 20.6+/-19.5). On the basis of multivariate logistic regression, the only clinical measure which significantly predicted group membership was the SANS Affective Flattening score (odds ratio=1.24; 95% CI=1.06-1.43). Our findings strongly suggest that catatonic COS differs from COS in ways that extend beyond motor symptoms. The SANS and SAPS scales, commonly used in schizophrenia, are not detailed enough to accurately describe catatonia in COS. The use of a catatonia rating scale is recommended to enhance recognition of and research into COS with catatonia.

[Interrelation between perinatal risk factors and problems of psychomotor development]

The problems developed in the perinatal period are the main reason of a delay of psycho-motor development. Early revealing and adequate conducting of the perinatal period, definition of existing or expected problems and intervention preventive measures allows avoiding or reducing possible pathological conditions, their complications and their consequences. The goal of investigation was to reveal interrelation between perinatal (features of pregnancy, features of delivery, intrauterine chronic hypoxic condition and intrauterine acute hypoxic condition) risk factors and problems of psychomotor development. The cohort of 331 newborn infants was investigated. A close interrelation between perinatal risk factors (features of pregnancy, features of delivery, intrauterine chronic hypoxic condition and intrauterine acute hypoxic condition) and problems of psychomotor development was revealed. It was found that early reveal of existing or expected problems together with intervention of preventive measures allow avoiding or reducing possible pathological conditions, their complications and their consequences.

Crying behaviour in early infancy is associated with developmental outcome at two years of age in very low birth weight infants

AIM

To evaluate the association between infant fussing and crying and developmental outcome in very low birth weight (VLBW) infants.

METHODS

Hundred and seventeen VLBW infants were followed up to 24 months of corrected age. The duration of fussing and crying and frequency of fuss/cry bouts were measured at term 6 weeks and 5 months of corrected age. Cognitive and motor development was assessed at 24 months of corrected age.

RESULTS

The increased duration of combined fuss/cry at term associated with lower psychomotor developmental index (PDI), [regression coefficient (b)=-0.83, p=0.025]. Crying at term associated negatively with mental developmental index (MDI) (b=-0.91, p=0.040) and PDI (b=-1.10, p=0.015). The associations between fuss/cry and PDI, and crying and PDI persisted in multiple regression analysis (b=-0.89, p=0.030 and b=-1.23, p=0.018, respectively). Excessive fuss/cry (>or=180 min/day) at term associated with lower PDI (p=0.005) and at 6 weeks with lower MDI (p=0.024) and PDI (p=0.012). Increase in the frequency of fuss/cry bouts at 5 months associated with higher PDI in both simple (b=2.90, p=0.045) and in multiple regression analysis (b=3.60, p=0.019).

CONCLUSIONS

In VLBW infants, longer duration of fussing and crying in very early infancy, but not at 5 months, is associated with less optimal development at 24 months of age.

Experimental evidence for a motivational origin of cognitive impairment in major depression

BACKGROUND

Diagnostic criteria and empirical evidence support the existence of cognitive deficits in depression. However, depressed mood, loss of interest and low self-efficacy might influence cognitive performance.

METHOD

Goal-setting instructions were used to promote motivation in depressed patients and control subjects during neuropsychological assessment. The resulting performance was compared with performance using standard instructions. Sixty in-patients with non-psychotic unipolar depression and 60 age- and education-matched healthy control subjects were assessed with standard neuropsychological tests [the Auditory Verbal Learning Test (AVLT), the Digit Symbol Test (DST), the Regensburg Word Fluency Test (RWT), and the Number Combination Test (Zahlen-Verbindungs-Test, ZVT)] using either goal-setting or standard test instructions.

RESULTS

Depressed patients showed lower baseline performance and lower generalized self-efficacy (p<0.0005) than controls. However, goal-setting instructions significantly improved patients' memory performance by 10% [AVLT: F(5, 54)=3.611, p=0.007] and psychomotor performance by 13% [ZVT: F(3, 56)=3.667, p=0.017]. Consequently, patients and control subjects demonstrated similar results when goal-setting instructions were applied. Goal-setting instructions showed a statistical trend, increasing patients' performance in the DST by 12% [F(1, 58)=2.990, p=0.089], although their verbal fluency measured by the RWT did not increase. No significant correlations of increased performance with generalized self-efficacy were found.

CONCLUSIONS

Cognitive deficits in depressed patients are influenced by motivational shortcomings. Because generalized self-efficacy failed to correlate to increased test performance, future research needs to disentangle the effective components of goal-setting instructions. Task-specific self-efficacy as well as enhancement of task-focused attention might underlie the significant goal-setting effect in depressed patients.

Neurological evaluation of patients with Gaucher disease diagnosed as type 1

Type 1 Gaucher disease (GD1) is characterised by lack of central nervous system involvement; however, there are several reports of associated neurological manifestations. The aim of this study was to systematically evaluate neurological manifestations in 31 patients with GD1 (12 males and 19 females; mean age 39.4 (range 5-77) years). Participants underwent a complete neurological examination and cognitive tests. Investigation of symptoms and medication intake, and motor and sensory electroneurograms were obtained. 30.7% of adult patients had neurological deficits, including psychomotor delay, parkinsonism, dementia, impaired saccadic ocular movements and peripheral nerve dysfunction. Three patients were redefined as type 3 GD. Electrodiagnosis was performed on 15 patients; 26.7% had reduced amplitude and/or abnormal waveforms in at least three nerves, 33.3% had a mild reduction in amplitude of two nerves and 40% had amplitude reduction in one nerve. Patients with three or more affected nerves had additional neurological symptoms. Our results demonstrate that neurological alterations occur in patients diagnosed with GD1, and subclinical peripheral neuropathy is a frequent finding.

Cognitive and motor features in elderly people with bipolar disorder

BACKGROUND

Although elderly people will represent one third of the bipolar population in a few years, data about cognitive and motor features in these patients are very scarce. The aim of this study was to compare the cognitive and motor functioning between elderly euthymic patients with bipolar disorder (BD) and healthy controls, as well as to determine the degree of correlation with psychosocial functioning.

METHODS

Euthymic older adults with BD (n=20) and healthy controls (n=20) were evaluated with traditional clinical instruments and measures of exposure to psychotropic drugs and extrapyramidal symptoms. All subjects completed an extensive neuropsychological battery.

RESULTS

Patients with BD had more extrapyramidal symptoms and worse performance than healthy controls in psychomotor speed, verbal memory, and executive functions even after controlling sub-clinical symptomatology. These findings were not associated with age at onset or length of illness or with current pharmacological exposure. Psychosocial functioning correlated negatively with performance in psychomotor speed and executive function, and with extrapyramidal symptoms.

LIMITATIONS

The small sample size and cross-sectional design.

CONCLUSIONS

Older adult patients with BD in a euthymic state could have a similar cognitive and motor profile to that described in younger euthymic bipolar patients. Cognitive-motor disturbances may help to explain impairments in daily functioning among elderly patients with bipolar disorder during remission.

[Psychomotor symptoms in schizophrenia: the importance of a forgotten syndrome]

BACKGROUND

Patients with schizophrenia display catatonia, psychomotor retardation, neurological soft signs (NSS) and neurological hard signs. There is considerable confusion about these psychomotor symptoms.

AIM

To discuss the symptoms with the help of the existing literature.

METHOD

Relevant articles were retrieved from Medline. results These psychomotor symptoms are intrinsic features of the illness and cannot be regarded as mere side effects of treatment with antipsychotics. The symptoms seem to become progressively worse in the course of the illness and are associated with a poor prognosis. In contrast to cognitive symptoms, psychomotor symptoms are associated with positive symptoms. The various psychomotor symptoms are associated with the same brain structures and may themselves be interlinked.

CONCLUSION

There is therefore considerable evidence to support the existence of a cluster of psychomotor symptoms, in addition to positive, negative and cognitive symptoms.

Mathematics learning disabilities in girls with fragile X or Turner syndrome during late elementary school

The present study focuses on math and related skills among 32 girls with fragile X (n = 14) or Turner (n = 18) syndrome during late elementary school. Performance in each syndrome group was assessed relative to Full Scale IQ-matched comparison groups of girls from the general population (n = 32 and n = 89 for fragile X syndrome and Turner syndrome, respectively). Differences between girls with fragile X and their comparison group emerged on untimed arithmetic calculations, mastery of counting skills, and arithmetic problem verification accuracy. Relative to girls in the comparison group, girls with Turner syndrome did not differ on untimed arithmetic calculations or problem verification accuracy, but they had limited mastery of counting skills and longer response times to complete the problem verification task. Girls with fragile X or Turner syndrome also differed from their respective comparison groups on math-related abilities, including visual-spatial, working memory, and reading skills, and the associations between math and those related skills. Together, these findings support the notion that difficulty with math and related skills among girls with fragile X or Turner syndrome continues into late elementary school and that the profile of math and related skill difficulty distinguishes the two syndrome groups from each other.

[Correction of motor and affective symptoms of parkinsonism by selective serotonine reuptake inhibition antidepressant]

A study included 68 patients with parkinsonism: 43 of them were treated with proflusak (fluoxetin), which efficacy was assessed in the frames of randomized placebo-controlled study. The levels of motor disability, anxiety, depression and serum serotonin (S) concentration were measured. The prevalence of rigidity and hypokinesia caused the increase of the depression level, along with decreasing of S concentration. Severity of tremor was positively correlated with the level of anxiety and blood S. Significant differences between patients receiving proflusak and placebo were found. No changes in the levels of motor-affective symptoms were observed in the placebo group. In patients treated with proflusak, the subjective improvement of health was accompanied by the significant decrease of depression severity and reduction of movement deficit, in particular rigidity and hypokinesia. The blood concentration of S decreased significantly in comparison to the placebo group. Taking into account the mechanism of action of the drug studied (its belonging to SSRIs), these changes may reflect the alterations of serotonergic metabolism in the brain synapses.

[Values of tandem mass spectrometry in etiologic diagnosis of cerebral developmental retardation]

OBJECTIVES

To investigate the values of tandem mass spectrometry (MS/MS) in etiologic diagnosis and understanding therapeutic effect in cerebral developmental retardation, and to help patients in early diagnosis, treatment and favorable prognosis.

METHODS

One hundred and fifty-eight childhood patients with brain heteroplasia were tested from July 2004 to October 2006. The blood was collected on filter paper, punched and extracted into methanol solution with stable isotope labeled internal standards, then derivatized with butanolic-HCl. After preparation, the samples were analysed by tandem mass spectrometry. Eleven MS/MS-positive patients were further analyzed based on gas chromatography/mass spectrometry (GC/MS) analysis of urine, clinical course, and treatment outcome.

RESULTS

Eleven of 158 patients (7.0%) with inborn metabolic error were confirmed, including five with methylmalonic acidemia, two with propionic acidemia, one with ornithine transcarbamylase deficiency, one with maple syrup urine disease, one with phenylketonuria, and one with biotinidase deficiency. Among them, five were male, six were female, aged from 4 days to 21 months. The clinical manifestations were diverse, including mental developmental retardation or degradation (11 cases), convulsion (5 cases), coma (4 cases), vomiting (4 cases), malnutrition (4 cases), lethargy (3 cases), repeated infection (3 cases), hypotonia (2 cases), etc. Laboratory findings showed metabolic acidosis, hyperammonemia, hyperlactacidemia, anemia, etc. MRI findings of the brain showed cerebral atrophy, a pattern of bilateral T(2)W high signal intensity or/and T(1)W low signal intensity in cerebral white matter and multiple encephalomalacia or vesicular change, ect. In methylmalonic acidemia patients, the early onset with severe acidosis and coma have had a poor prognosis. Improvement was observed in 8 cases after treatment with vitamin B(12), L-carnitine, special milk, low-protein diet or biotin, etc. However 3 MMA patients died.

CONCLUSION

MS/MS was helpful for some patients in etiologic diagnosis and understanding therapeutic effect of cerebral developmental retardation. Early diagnosis and appropriate treatment are essential to improve the prognosis and prevent brain damage.

Growth and neurodevelopment outcome of very low birth weight infants delivered by preeclamptic mothers

AIM

To investigate growth and neurodevelopment outcome of very low birth weight (VLBW) infants delivered by preeclamptic mothers.

METHODS

A cohort including all VLBW infants delivered between December 2003 and May 2005 was followed up to 12 and 18 months corrected age (CA).

EXCLUSION CRITERIA

death before 1 year corrected age, major malformations, deafness and blindness. Weight, length and head circumference were plotted on NCHS curves. Bayley Scales were performed at 12 and 18 months CA.

RESULTS

40 infants in preeclamptic and 46 in control groups were studied. Birth weight and gestational age were 1148 g+/-236 and 1195 g+/-240, and 31.3 weeks+/-1 and 30.6 weeks+/-2 for preeclamptic and control groups, respectively. At 12 and 18 months, CA, weight for age (Z score) was significantly higher in control than in preeclamptic. PDI scores were higher in preeclamptic than in controls at 18 months CA.

CONCLUSIONS

Catch-up of body weight did not occur in the first 18 months CA in preeclamptic infants. Neurodevelopment outcome was better in infants delivered by preeclamptic mothers than in controls at 18 months CA.

The impaired hypothyroid patient: ethical considerations and obligations

OBJECTIVES

Analyze the ethical duties and dilemmas involved in treating the severely hypothyroid patient.

DESIGN

A critical review of the literature was conducted with respect to clinical ethics issues pertaining to severe hypothyroidism; legal and ethical guidelines for consent and capacity in the context of severe hypothyroidism; health case law involving the duty to warn third parties; and comparable clinical conditions resulting in impaired driving and the performance of critical tasks.

MAIN OUTCOME

Neuropsychological studies and accepted clinical experiences verify the variable degrees of intellectual and neurological impairment consequent to severe hypothyroidism. Thus, severely hypothyroid patients are considered impaired in the performance of specific tasks, such as driving. Consequent to that, they may be agents of harm as a result of their impairment if they are not warned against driving or performing other duties affecting public safety. Severely hypothyroid patients may lack the capacity to make an informed decision, even when warned against driving or other tasks, and some may ignore such warnings.

CONCLUSIONS

The legal and ethical "duty to warn" may trump confidentiality and HIPAA in cases where the activity of impaired patients seriously affects public safety. Not only do health care providers have a clear duty to warn patients not to drive, but in some extreme cases, may have a duty to warn third parties when a patient's driving or occupational duties place the public in harm's way.

Elemental mercury poisoning probably causes cortical myoclonus

Mercury toxicity causes postural tremors, commonly referred to as "mercurial tremors," and cerebellar dysfunction. A 23-year woman, 2 years after injecting herself with elemental mercury developed disabling generalized myoclonus and ataxia. Electrophysiological studies confirmed the myoclonus was probably of cortical origin. Her deficits progressed over 2 years and improved after subcutaneous mercury deposits at the injection site were surgically cleared. Myoclonus of cortical origin has never been described in mercury poisoning. It is important to ask patients presenting with jerks about exposure to elemental mercury even if they have a progressive illness, as it is a potentially reversible condition as in our patient.

Sublingual buprenorphine/naloxone precipitated withdrawal in subjects maintained on 100mg of daily methadone

RATIONALE

Acute doses of buprenorphine can precipitate withdrawal in opioid dependent persons. The likelihood of this withdrawal increases as a function of the level of physical dependence.

OBJECTIVES

To test the acute effects of sublingual buprenorphine/naloxone tablets in volunteers with a higher level of physical dependence. The goal was to identify a dose that would precipitate withdrawal (Phase 1), then determine if withdrawal could be attenuated by splitting this dose (Phase 2).

METHODS

Residential laboratory study; subjects (N=16) maintained on 100mg per day of methadone. Phase 1: randomized, double blind, triple dummy, within subject study. Conditions were sublingual buprenorphine/naloxone (4/1, 8/2, 16/4, 32mg/8mg), intramuscular naloxone (0.2mg), oral methadone (100mg), or placebo. Medication conditions were randomized, but buprenorphine/naloxone doses were ascending within the randomization. Phase 2: Conditions were methadone, placebo, naloxone, 100% of the buprenorphine/naloxone dose that precipitated withdrawal in Phase 1 (full dose), and 50% of this dose administered twice in a session (split dose). Analyses covaried by trough methadone serum levels.

RESULTS

Six subjects did not complete the study. Of the 10 who completed, 3 tolerated up to 32mg/8mg of buprenorphine/naloxone without evidence of precipitated withdrawal. For the seven completing both phases, split doses generally produced less precipitated withdrawal compared to full doses.

CONCLUSIONS

There is considerable between subject variability in sensitivity to buprenorphine's antagonist effects. Low, repeated doses of buprenorphine/naloxone (e.g., 2mg/0.5mg) may be an effective mechanism for safely dosing this medication in persons with higher levels of physical dependence.