Biomedical subjects

Acioly L T Lacerda

Publications and source records attributed to Acioly L T Lacerda.

9 recordsLinked to original sources

PubMed2006

Magnetic resonance imaging study of the orbitofrontal cortex in autism.

The orbitofrontal cortex is involved in multiple psychologic functions, such as emotional and cognitive processing, learning, and social behavior. These functions are variably impaired in individuals with autism. The present study examined the size of the orbitofrontal cortex, and its medial and lateral subdivisions, using magnetic resonance imaging (MRI) scans obtained from 40 non-mentally retarded individuals with autism and 41 healthy controls. No differences were observed between the two groups on any of the orbitofrontal cortex measurements. However, when compared with controls, a smaller right lateral orbitofrontal cortex was observed in children and adolescents with autism, whereas a larger right lateral orbitofrontal cortex was found in adult patients. Interestingly, a positive relationship was found in the patient group between circumscribed interests and all orbitofrontal cortex structures. The present study suggests the absence of global volumetric abnormalities in the orbitofrontal cortex in autism and indicates that the functional disturbances in this structure might not be related to anatomic alterations.

Adolescent↗

PubMed2005

[Brain effects of cannabis--neuroimaging findings].

Cannabis is the most widely used illicit drug. Despite this, only a small number of studies have investigated the long-term neurotoxic consequences of cannabis use. Structural and functional neuroimaging techniques are powerful research tools to investigate possible cannabis-induced pathophysiological changes. A computer literature review was conducted in the MEDLINE and PsycLIT databases between 1966 and November of 2004 with the search terms 'cannabis', 'marijuana', 'neuroimaging', 'magnetic resonance', 'computed tomography', 'positron emission tomography', 'single photon emission computed tomography", 'SPET', 'MRI' and 'CT'. Structural neuroimaging studies have yielded conflicting results. Most studies report no evidence of cerebral atrophy or regional changes in tissue volumes, and one study suggested that long-term users who started regular use on early adolescence have cerebral atrophy as well as reduction in gray matter. However, several methodological shortcomings limit the interpretation of these results. Functional neuroimaging studies have reported increases in neural activity in regions that may be related with cannabis intoxication or mood-change effects (orbital and mesial frontal lobes, insula, and anterior cingulate) and decreases in activity of regions related with cognitive functions impaired during acute intoxication. The important question whether residual neurotoxic effects occur after prolonged and regular use of cannabis remains unclear, with no study addressing this question directly. Better designed neuroimaging studies, combined with cognitive evaluation, may be elucidative on this issue.

Atrophy↗

PubMed2005

Urinary pH in panic disorder.

Urinary pH was evaluated in panic disorder (PD) patients compared with both psychiatric and healthy control subjects. Fourteen PD patients, eight major depressive disorder (MDD) patients, and 14 healthy control (HC) subjects were examined. All patients were drug-free and met DSM-IV diagnostic criteria. The PD patients had lower urinary pH and higher levels of anxiety than both MDD and HC subjects. Additionally, urinary pH inversely correlated with anxiety levels. Although preliminary, these findings suggest that PD patients have lower urinary pH than MDD and HC subjects. Future studies that simultaneously examine both urinary and blood pH in larger numbers of PD patients and patients with other anxiety disorders, before and after treatment, need to be conducted.

Anxiety↗

PubMed2004

Anatomical MRI study of corpus callosum in unipolar depression.

Previous studies have suggested abnormal cerebral lateralization in major depressive disorder (MDD). Few controlled MRI studies have investigated the corpus callosum (CC), the largest commissura connecting the two cerebral hemispheres, in MDD. This study investigated anatomical abnormalities in the CC and its subdivisions in MDD patients. Twenty-two unmedicated MDD patients and 39 healthy subjects underwent brain magnetic resonance imaging (MRI). Measurements of the CC and its sub-regions were performed with a semi-automated software (NIH Image, version 1.62). ANCOVA with age, gender, and intra-cranial volume (ICV) as covariates showed no significant differences in CC measurements between patients and controls (df=1,56; p>0.05). However, patients with familial MDD had a significantly larger middle genu area (F(1,45)=4.252; p=0.045) compared to healthy controls, and significantly larger middle genu (F(1,13)=5.366; p=0.037), anterior splenium (F(1,13)=6.27; p=0.026), and middle splenium areas (F(1,13)=4.706; p=0.049) compared to patients with non-familial MDD. Although preliminary, our findings suggest that anatomical abnormalities in CC may be restricted to patients with familial MDD, with possible enlargement of CC in this particular sub-group. The possible role of callosal abnormalities in the pathogenesis of mood disorders should be further examined.

Adolescent↗

PubMed2004

Anatomic evaluation of the orbitofrontal cortex in major depressive disorder.

BACKGROUND: The orbitofrontal cortex (OFC) plays a major role in neuropsychologic functioning including exteroceptive and interoceptive information coding, reward-guided behavior, impulse control, and mood regulation. This study examined the OFC and its subdivisions in patients with MDD and matched healthy control subjects. METHODS: Magnetic resonance imaging (MRI) was performed on 31 unmedicated MDD and 34 control subjects matched for age, gender, and race. Gray matter volumes of the OFC and its lateral and medial subdivisions were measured blindly. RESULTS: The MDD patients had smaller gray matter volumes in right medial [two-way analysis of covariance F(1,60) = 4.285; p =.043] and left lateral OFC [F(1,60) = 4.252; p =.044]. Left lateral OFC volume correlated negatively with age in patients but not in control subjects. Male, but not female patients exhibited smaller left and right medial OFC volumes compared with healthy control subjects of the same gender. CONCLUSIONS: These findings suggest that patients with MDD have reduced OFC gray matter volumes. Although this reduction might be important in understanding the pathophysiology of MDD, its functional and psychopathologic consequences are as yet unclear. Future studies examining the relationship between specific symptomatic dimensions of MDD and OFC volumes could be especially informative.

Adult↗

PubMed2003

Anatomical MRI study of basal ganglia in major depressive disorder.

The basal ganglia form a part of the brain neuroanatomic circuits that may be involved in mood regulation. Decreases in basal ganglia volumes have been previously reported in major depressive disorder patients in comparison to healthy controls. In this study, we measured caudate, putamen, and globus pallidus volumes in 25 patients with major depressive disorder (4 M; age+/-S.D.=41+/-11 years) and 48 healthy controls (29 M; age+/-S.D.=35+/-10 years), using high-resolution magnetic resonance imaging (MRI), in an attempt to replicate prior findings. Unlike most previous studies, we did not find significant differences between patient and control groups in basal ganglia volumetric measures. Nonetheless, there was a significant interaction between diagnosis and cerebral hemisphere, with MDD patients showing decreased asymmetry in globus pallidus volumes in comparison with healthy controls. Furthermore, in the patient group, left putamen volumes correlated inversely with length of illness, and left globus pallidus volume correlated directly with number of prior depressive episodes. These findings suggest that abnormalities in lateralization and possibly neurodegenerative changes in basal ganglia structures participate in the pathophysiology of major depressive disorder.

Adolescent↗

PubMed2003

Elevated thalamic and prefrontal regional cerebral blood flow in obsessive-compulsive disorder: a SPECT study.

Functional neuroimaging studies have pointed to a possible role of cerebral circuits involving the prefrontal and anterior cingulate cortices, the striatum, and thalamus in the pathophysiology of obsessive-compulsive disorder (OCD). Regional cerebral blood flow (rCBF) of 16 drug-free Brazilian patients with OCD and 17 healthy subjects matched for age, gender, handedness and level of education was measured with [99m-Tc] HMPAO single photon emission computed tomography. Analysis of covariance identified four regions of interest with significantly higher rCBF: the right superior and inferior frontal cortex and the right and left thalamus. Positive correlations between symptom severity measured by Clinical Global Impression scores and rCBF were found in the right and left inferior frontal lobes and in the right basal ganglia. Compulsive behavior was inversely correlated with rCBF in the right thalamus, and duration of illness correlated positively with rCBF in the right and left superior frontal lobes and with the right thalamus. The findings of this SPECT study conducted in Brazil are in agreement with prior studies and provide additional support for the involvement of prefrontal-subcortical circuits in the pathophysiology of OCD. Furthermore, the study suggests that similar brain mechanisms appear to be involved cross-culturally.

Adolescent↗

PubMed2003

Neuropsychological performance and regional cerebral blood flow in obsessive-compulsive disorder.

Convergent findings from neuropsychological and neuroimaging studies have suggested that neural dysfunction in frontal-subcortical circuits may play a central role in the pathophysiology of obsessive-compulsive disorder (OCD). To further examine the relationship between these two sets of findings we investigated both neuropsychological functions and regional cerebral blood flow (rCBF) in a combined study. Fourteen unmedicated patients fulfilling DSM-IV criteria for OCD and 14 healthy controls matched for age, gender, handedness, and education were assessed on neuropsychological tests that included Trail Making Test (TMT), Rey Complex Figure Test (RCF) (copy and 5-min recall), Verbal Fluency Test (VFT), and Wisconsin Card Sorting Test (WCST). rCBF was studied with 99 mTc-hexamethyl-propyleneamine-oxime (HMPAO) single photon emission computed tomography (SPECT). Patients performed more poorly than controls (P<.05) on RCF (copy), VFT, and WCST (perseverative errors). Spearman's correlations indicated that severity of OCD correlated inversely with performance on the RCF (copy and recall scores) and positively with rCBF in the right thalamus. Positive correlations were observed between nonperseverative errors (WCST) and rCBF in frontal areas and anterior cingulate. Perseverative errors (WCST) correlated negatively with rCBF in the right thalamus. These findings are consistent with most previously published studies and suggest neural dysfunctions in the frontal-subcortical circuits probably more pronounced in the right hemisphere. They also extend the existing research, showing associations between deficits in cortical-subcortical circuitry and performance on neuropsychological tests of controlled attention and visuospatial functions.

Adolescent↗

PubMed2003

Measurement of the orbitofrontal cortex: a validation study of a new method.

The orbital frontal cortex (OFC) plays a critical role in the pathophysiology of several neuropsychiatric disorders. Few morphometric neuroimaging studies have examined the OFC using different methodologies and have reported discrepant values. Substantial variability in gyri and sulci across individuals as well as unclear landmarks underline the difficulties in obtaining accurate and reliable measurements. We propose a new geometrical method for measuring the OFC taking into account individual brain variability. The OFC was defined by using the intercommissural line and the inferior edge of the frontal lobe as the main landmarks. The medial and lateral subdivisions of OFC were also separately measured using the olfactory sulcus as the boundary to distinguish between them. After resampling and refitting, 10 scans were independently traced by two trained researchers using BRAINS software. Talairach coordinates were identified on each scan from the OFC and surrounding adjacent brain regions to assess the validity of this method. Brain regions were assigned using Talairach Daemon system. OFC volumes were comparable with those previously reported. Sensitivity and specificity for OFC gray matter were 87.6 and 84.8%, respectively. Intraclass coefficients (ICCs) for gray, white, and total OFC were 0.995, 0.994, and 0.997, respectively. ICCs for OFC medial and lateral subdivisions ranged between 0.996 and 0.998. This method appears to be a valid method for measuring the OFC with excellent reliability. This uncomplicated approach is easy to apply and has the potential to be a valuable alternative to the previously published methods.

Adult↗