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Preclinical and clinical studies suggest that males and females may be differentially affected by cannabis use. This study evaluated the interaction of cannabis use and biological sex on cognition, and the association between observed cognitive deficits and features of cannabis use.
Cognitive measures were assessed in those with regular, ongoing, cannabis use (N = 40; 22 female) and non-using peers (N = 40; 23 female). Intelligence, psychomotor speed, and verbal working memory were measured with the Wechsler Abbreviated Scale of Intelligence, Digit Symbol Test, and Digit Span and Hopkins Verbal Learning Test, respectively. Associations between cognitive measures and cannabis use features (e.g., lifetime cannabis use, age of initiation, time since last use of cannabis, recent high-concentration tetrahydrocannabinoid exposure) were also evaluated.
No main effects of group were observed across measures. Significant interactions between group and biological sex were observed on measures of intelligence, psychomotor speed, and verbal learning, with greatest group differences observed between males with and without regular cannabis use. Psychomotor performance was negatively correlated with lifetime cannabis exposure. Female and male cannabis use groups did not differ in features of cannabis use.
Findings suggest that biological sex influences the relationship between cannabis and cognition, with males potentially being more vulnerable to the neurocognitive deficits related to cannabis use.
The use of different imaging modalities provides the clinician and researcher with different views of anatomy and physiology at unprecedented levels of detail. Multimodal imaging allows for noninvasive measurement of structure and function in humans during complex behavior, and thus provides information about the inner workings of the brain previously unavailable. The present paper examines the various imaging techniques available, and describes their application to the clinic—in the case of epilepsy—and to research—in the case of schizophrenia. Because the electroen-cephalogram has a dynamic response in milliseconds, it provides the best temporal sensitivity of functional measures of brain activity. When coupled with high-resolution magnetic resonance imaging measures of brain structure, this multimodal approach provides a powerful tool for understanding brain activity. Clinically, the use of multimodal imaging has provided greater precision in localization of the epileptogenic focus. For researchers attempting to determine the underlying causes of schizophrenia, the use of multimodal imaging has helped lead the field away from a specific lesion view to a more distributed system abnormality view of this disorder.
Disturbances of visual perception frequently accompany neurodegenerative disorders but have been little studied in Huntington's disease (HD) gene carriers. We used psychophysical tests to assess visual perception among individuals in the prediagnostic and early stages of HD. The sample comprised four groups, which included 201 nongene carriers (NG), 32 prediagnostic gene carriers with minimal neurological abnormalities (PD1); 20 prediagnostic gene carriers with moderate neurological abnormalities (PD2), and 36 gene carriers with diagnosed HD. Contrast sensitivity for stationary and moving sinusoidal gratings, and tests of form and motion discrimination, were used to probe different visual pathways. Patients with HD showed impaired contrast sensitivity for moving gratings. For one of the three contrast sensitivity tests, the prediagnostic gene carriers with greater neurological abnormality (PD2) also had impaired performance as compared with NG. These findings suggest that early stage HD disrupts visual functions associated with the magnocellular pathway. However, these changes are only observed in individuals diagnosed with HD or who are in the more symptomatic stages of prediagnostic HD. (JINS, 2008, 14, 446–453.)
Thought disorder in schizophrenia may involve abnormal
semantic activation or faulty working memory maintenance.
Event-related potentials (ERPs) were recorded while sentences
reading “THE NOUN WAS ADJECTIVE/VERB”
were presented to 34 schizophrenic and 34 control subjects.
Some nouns were homographs with dominant and subordinate
meanings. Their sentence ending presented information crucial
for interpretation (e.g., The bank was [closed,
steep]). Greatest N400 activity to subordinate
homograph-meaning sentence endings in schizophrenia would
reflect a semantic bias to strong associates. N400 to all
endings would reflect faulty verbal working memory maintenance.
Schizophrenic subjects showed N400 activity to all endings,
suggesting problems in contextual maintenance independent
of content, but slightly greater N400 activity to subordinate
endings that correlated with the severity of psychosis.
Future research should help determine whether a semantic
activation bias in schizophrenia toward strong associates
is reflected in ERP activity or whether this effect is
overshadowed by faulty verbal working memory maintenance
Event-related potentials (ERPs) provide a noninvasive
method to evaluate neural activation and cognitive processes
in schizophrenia. The pathophysiological significance of
these findings would be greatly enhanced if scalp-recorded
ERP abnormalities could be related to specific neural circuits
and/or regions of the brain. Using quantitative approaches
in which scalp-recorded ERP components are correlated with
underlying neuroanatomy in schizophrenia, we focused on
biophysical and statistical procedures (partial least squares)
to relate the auditory P300 component to anatomic measures
obtained from quantitative magnetic resonance imaging.
These findings are consistent with other evidence that
temporal lobe structures contribute to the generation of
the scalp-recorded P300 component and that P300 amplitude
asymmetry over temporal recording sites on the scalp may
reflect anatomic asymmetries in the volume of the superior
temporal gyrus in schizophrenia.
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