Biomedical subjects

Perry F Renshaw

Publications and source records attributed to Perry F Renshaw.

79 records · Page 5Linked to original sources

PubMed2002

Effects of methylphenidate on functional magnetic resonance relaxometry of the cerebellar vermis in boys with ADHD.

OBJECTIVE: The authors used functional magnetic resonance imaging (fMRI) to test the effects of methylphenidate on steady-state blood volume in the midline vermis of the cerebellum in boys with attention deficit hyperactivity disorder (ADHD). This region was selected as it has been observed to be significantly smaller in children with ADHD. Also, in preclinical studies, the vermis has been shown to modulate forebrain dopamine systems, to influence locomotor activity, and to contain a significant density of dopamine transporters. METHOD: T(2) relaxometry was used to indirectly assess blood volume in the cerebellum (hemispheres and midline vermis) of 10 boys with ADHD who were administered placebo or one of three different doses of methylphenidate continuously for 1 week. T(2) relaxation time values are inversely proportional to local cerebral blood volume. After each week of treatment, and within 1-3 hours of the boys' afternoon dose, testing for drug efficacy was performed by using objective measures of activity. RESULTS: Moderate and high doses of methylphenidate increased T(2) relaxation time in a rate-dependent manner-increasing T(2) relaxation time in the most active children with ADHD and reducing T(2) relaxation time in subjects with ADHD who were not objectively hyperactive. CONCLUSIONS: This preliminary study supports a role for the vermis in ADHD and suggests that further research is needed to clarify the relationship between vermal size, vermal blood flow, stimulant response, and the developmental pathophysiology of ADHD.

Attention↗

PubMed2002

Videotaped cue for urge to drink alcohol.

BACKGROUND: The urge to drink alcohol can be robustly and reliably induced via actual exposure to a person's preferred alcoholic beverage. Unfortunately, these exposure paradigms are unwieldy for functional magnetic resonance imaging studies. The goal of this study was to examine whether viewing a personalized videotaped cue could induce alcohol craving. The following hypotheses were tested: (1) individualized cue videotapes can reliably elicit the urge to drink alcohol in alcohol-dependent participants and (2) alcohol drinking histories can predict reactivity to cue. METHODS: DSM-IV criteria were used to identify an alcohol-dependent group (ADG). Controls included a light-drinking group and a moderate-drinking group. Urge to drink alcohol was assessed at baseline and after each of five in vivo exposure conditions: water (W), alcohol 1 (A1), mood induction (M), alcohol 2 (A2), and relaxation (R). The entire exposure session was videotaped. Each participant's video footage was digitally edited to produce a 17.5-min cue that was presented to the participant 24 to 72 hr later. Ratings of urge to drink alcohol across the five exposure conditions were compared for both the in vivo and the video exposure sessions. RESULTS: Fourteen participants (five in the light-drinking group, four in the moderate-drinking group, and five in the ADG) completed both sessions. Participants in each group showed differences between neutral cue exposure (W and R) and alcohol-related cue exposure (A1, M, and A2) in both the in vivo cue session (p < 0.002) and the videotape session (p < 0.02). Post hoc comparisons among the groups to alcohol-related cues established that, in both sessions (p(in vivo) = 0.04; p(videotape) = 0.04), the ADG demonstrated the greatest urge to drink. CONCLUSIONS: Alcohol cue reactivity can be reliably induced and assessed in alcohol-dependent participants via personalized videotapes. History of alcohol consumption is positively correlated with the degree of cue reactivity. This study advances our ability to assess alcohol cue reactivity in the absence of alcohol.

Adult↗

PubMedDate not supplied

Shape changes of the corpus callosum in abstinent methamphetamine users.

The objective of the current study was to evaluate structural changes of the corpus callosum (CC) in abstinence methamphetamine (MA) users. Shape and size of the CC in 27 MA users were compared to those of 18 healthy comparison subjects. To define the local curvature and width of the CC, medial model-based shape analysis was performed using CC skeletons extracted from a distance map. To define the local displacement of the CC, a boundary model-based shape analysis was performed. In addition, the size of regional areas of the CC was measured according to the Witelson's definition for comparison. In the medial model-based shape analysis, increased curvature in the genu (curvature angle difference = 4.1 degrees) and decreased width in posterior midbody (width difference = 0.77 mm) and isthmus area (width difference = 0.86 mm) of the CC were observed in MA users relative to healthy comparison subjects. In the boundary model-based shape analysis, significant displacement was observed in MA users where there were differences in shape/width patterns by the medial model-based shape analysis. There were no differences in the size of regional areas of the CC between groups. Findings suggest that MA use is associated with regional changes in interhemispheric white matter tracts, which connect frontal and parietal cortices and that these frontal and parietal abnormalities may underlie clinical manifestations of the MA abuse.

Adult↗

PubMedDate not supplied

Abnormal T2 relaxation time in the cerebellar vermis of adults sexually abused in childhood: potential role of the vermis in stress-enhanced risk for drug abuse.

Recent studies suggest that childhood sexual abuse (CSA) elicits a cascade of neurohumoral events that affect brain development and is also a risk factor for the later development of substance abuse. We hypothesize that the cerebellar vermis may be a key region linking these observations. The vermis has a protracted ontogeny and a high density of glucocorticoid receptors, rendering it highly susceptible to early stress. The vermis modulates dopamine turnover in the accumbens and receives direct dopamine input through fibers with dopamine transporters. To test this hypothesis, steady-state functional magnetic resonance imaging (fMRI) (T2 relaxometry) was performed to assess resting blood flow in the vermis of 24 young adults (18-22 years) selected by screening from a large community sample. Eight subjects had a history of repeated CSA but were unmedicated and not under psychiatric care. Sixteen subjects were age-matched controls who had no personal or family history of Axis I psychiatric disorders. All subjects were screened to exclude known abnormalities affecting brain development, and any history of drug or alcohol abuse. CSA subjects had higher T2 relaxation time (T2-RT) than controls in the vermis but not in cerebral or cerebellar hemispheres. Vermal T2-RT correlated strongly with Limbic System Checklist (LSCL-33) ratings of temporal lobe epilepsy (TLE)-like symptomatology. From 537 prescreened young adults we found that their frequency of substance use was associated with a monotonic increase in LSCL-33 ratings and depression scores. Together these findings suggest that early trauma may interfere with the development of the vermis, and produce neuropsychiatric symptoms associated with drug use.

Adolescent↗

PubMedDate not supplied

White matter hyperintensities on magnetic resonance imaging of the brain in children with psychiatric disorders.

The current study sought to determine the prevalence, severity, and location of white matter signal hyperintensities (WMH) on brain magnetic resonance imaging assessments of children and adolescents with psychiatric disorders. Seventy-one percent (N = 934) of children admitted to the McLean Hospital Child and Adolescent inpatient treatment unit were evaluated with the Diagnostic Interview Schedule for Children (DISC) within 7 days of admission during the period 1988 to 1993 (total, 1,308 admissions). Four hundred eight of these subjects (43.7%) were referred for brain magnetic resonance imaging (MRI) scans and became our study subjects (mean age, 12.4 years [SD = 2.7]; male/female, 230/178). Study subjects were grouped according to a hierarchical diagnostic system as follows: schizophrenia (n = 42), bipolar disorder (n = 56), unipolar depression (n = 94), conduct disorder/attention deficit disorder (n = 103), and other neurotic disorders (n = 30). Subjects without any level 2 diagnosis on DISC (n = 83) constituted the comparison group. Bipolar disorder, unipolar depression, and conduct disorder/attention deficit disorder groups were significantly more likely to have severe levels of WMH than the comparison group (prevalence rates: 17.9%, 13.8%, 13.6% v 1.2%). In addition, the bipolar disorder group was significantly more likely to have severe levels of WMH than the schizophrenia group (prevalence rates: 17.9% v 2.4%). The frontal lobes were the predominant locations of WMH in the bipolar disorder and unipolar depression groups (76.9% and 60.0%, respectively) and also the most frequent location for the conduct disorder/attention deficit disorder group (35.7%). The current study reports an increased prevalence and severity of WMH in children with bipolar disorder, unipolar depression, and conduct disorder/attention deficit disorder relative to the comparison group and in children with bipolar disorder compared to those with schizophrenia. The development of brain WMH, especially in the frontal lobes, may play a role in the pathophysiology of affective disorders in children and adolescents.

Adolescent↗

PubMedDate not supplied

Brain proton magnetic resonance spectroscopy in Alzheimer disease: changes after treatment with xanomeline.

Patients with mild-to-moderate Alzheimer disease received transdermal xanomeline, an M1-selective cholinergic agonist, or placebo for 4 months. Clinical assessments and proton magnetic resonance spectroscopic imaging examinations were carried out at baseline, and after 8 and 16 weeks of treatment. There was a positive correlation between change from baseline in parietal lobe gray-matter cytosolic choline, expressed in terms of choline/creatine resonance ratios, and cognitive performance as measured with the Alzheimer's Disease Assessment Scale Cognitive Subscale. Specifically, increased levels of cytosolic choline, a precursor pool for acetylcholine synthesis, were associated with greater progression in memory impairment during treatment.

Administration, Cutaneous↗

PubMedDate not supplied

Clinical significance of brain white matter hyperintensities in young adults with psychiatric illness.

Magnetic resonance imaging (MRI) provides detailed images of brain anatomy, with especially clear definition of gray and white matter structures. Several brain MRI studies have suggested that adults with bipolar disorder (BD) are more likely to have "white matter hyperintensities" (WMH) than adults without BD. The disproportionately greater frequency of these lesions in otherwise physically healthy patients suggests that the illness itself, or treatments used to control the illness, may be risk factors for the development of white matter changes. Similarly, WMH may be an etiological factor for some types of BD. In addition to reviewing the relevant literature, this research study attempted to determine whether lithium treatment is associated with an increased prevalence of WMH in young adults with psychiatric illness. To test this hypothesis, we evaluated over 600 brain MRI scans from inpatients at McLean Hospital, Belmont, Massachusetts. We controlled for possible confounding variables such as age, vascular disease, substance abuse, and markers of illness severity. We found that individuals with BD were no more likely to have WMH than other psychiatric patients. Lithium use was nonsignificantly associated with the presence of WMH. A multivariate regression model for the presence of WMH showed that heart disease, female gender, and multiple psychiatric admissions were significant predictors of WMH. This study does not support previous findings that BD, compared to other psychiatric illnesses, was associated with increased risk of WMH. Lithium use may be subtly associated with WMH. Our results are consistent with previous research that found an association between cardiovascular disease, advanced age, and the presence of WMH, though our analysis appears to be unique in its inclusion of cardiovascular disease as a risk factor in young adults with psychiatric illness.

Adolescent↗