|
Current Psychiatry Reviews
ISSN: 1573-4 005
Current Psychiatry Reviews
Volume 3, Number 3, August 2007
Contents
Cannabis Use, First-Episode Psychosis, and Schizotypy:
A Summary and Synthesis of Recent Literature Pp.
161-171
Michael T. Compton, Sandra M. Goulding and Elaine F. Walker
[Abstract]
The Latent Structure of Mental Disorders: A Taxometric
Update on the Categorical vs Dimensional Debate Pp.
172-177
Nick Haslam
[Abstract]
Problems in Statistical Analysis of Attrition in Randomized
Controlled Clinical Trials of Antidepressant for Geriatric
Depression Pp. 178-185
Moonseong Heo, Andrew C. Leon, Barnett S. Meyers and George
S. Alexopoulos
[Abstract]
Issues in Rehabilitation of Cognitive Deficits in
Schizophrenia: A Critical Review Pp. 186-195
Gitry Heydebrand
[Abstract]
Physiologic Responses in Anxiety Pp. 196-204
Rudolf Hoehn-Saric
[Abstract]
Schizophrenia and Liver Dysfunction Caused by Portacaval
Shunting Pp. 205-212
Jens Krøll
[Abstract]
Cognitive Rehabilitation for Schizophrenia: A Review
of Recent Advances Pp. 213-221
Matthew M. Kurtz and Mary C. Nichols
[Abstract]
Transcranial Direct Current Stimulation – An
Adjuvant Tool for the Treatment of Neuropsychiatric Diseases?
Pp. 222-232
Michael A. Nitsche and Felipe Fregni
[Abstract]
Abstracts
[Back to top]
Cannabis Use, First-Episode Psychosis, and Schizotypy:
A Summary and Synthesis of Recent Literature
Michael T. Compton, Sandra M. Goulding and Elaine F. Walker
Schizophrenia currently is conceptualized as a neurodevelopmental
disorder, the expression of which is affected by both genetic
and environmental factors. Schizotypy is a dimensional personality
construct that is the substrate of schizotypal personality
disorder (SPD), and its positive, negative, and cognitive
features are subclinical manifestations that mirror the symptoms
of schizophrenia. Research indicates that both schizophrenia
and schizotypy are linked with cannabis use. In this overview,
recent literature on the following topics is summarized: (1)
cannabis use as a potential risk factor, or component cause,
of schizophrenia, (2) prevalence and clinical correlates of
cannabis use among individuals in the early course of schizophrenia,
(3) clinical and psychosocial outcomes of schizophrenia that
are influenced by cannabis use, and (4) associations between
cannabis use and schizotypy. Implications and future research
directions are discussed. Growing evidence points to the complex
and informative interconnections between cannabis use, schizotypy,
and first-episode psychosis.
[Back to top]
The Latent Structure of Mental Disorders: A Taxometric
Update on the Categorical vs Dimensional Debate
Nick Haslam
Taxometric analysis is a statistical methodology for testing
between categorical and dimensional models of latent variables.
This article reviews taxometric research on the structure
of mental disorders conducted since previous reviews in 2003,
a period in which the quantity of this work has more than
doubled. Taxometric studies have addressed a wide variety
of mental disorders whose status as discrete categories or
dimensional continua has been controversial, including unipolar
depression, schizophrenia subtypes, post-traumatic stress
disorder, and attention deficit-hyperactivity disorder. They
continue to yield categorical and dimensional findings with
approximately equal frequency, and with adequate levels of
replication. These findings are summarized, practical implications
are discussed, and several concerns about current taxometric
practice are raised.
[Back to top]
Problems in Statistical Analysis of Attrition in Randomized
Controlled Clinical Trials of Antidepressant for Geriatric
Depression
Moonseong Heo, Andrew C. Leon, Barnett S. Meyers and George
S. Alexopoulos
Attrition from clinical trials is unavoidable in geriatric
psychiatry and beyond. It results in incomplete data and consequently
imposes three fundamental challenges: greater bias, reduced
power, and less generalizability. In an effort to assess the
extent of attrition and the relevance of statistical methods
applied to analyze incomplete data in geriatric psychiatry,
we reviewed 69 published antidepressant randomized clinical
trials conducted since 1975. The median attrition rate estimated
from these trials was 26.6%; nevertheless, we found that many
trials lack data analytic strategies to address the problem
of attrition. Most of the applied statistical analyses involved
chi-square tests, t-tests, and analysis of variance (ANOVA),
each of which assume that data are missing completely at random.
Even when imputation for missing data due to attrition was
attempted, only the last observation carried forward (LOCF)
method was implemented. The LOCF imputation can actually increase
bias of the results in the analysis of repeatedly measured
outcomes. In addition, despite the longitudinal nature of
repeatedly measured outcomes, the statistical methods used
are for analysis of cross-sectional data. Thus, the data analytic
strategies did not adequately meet the challenges arising
from attrition. We encourage the use of mixed-effects models
to reduce the impact of attrition on bias, power and generalizability
in antidepressant RCTs for geriatric depression. For imputation,
we recommend use of multiple imputation methods instead of
LOCF.
[Back to top]
Issues in Rehabilitation of Cognitive Deficits in
Schizophrenia: A Critical Review
Gitry Heydebrand
Over the past 20 years, researchers have begun to examine
whether remediation of cognitive deficits could improve cognitive
performance in individuals with schizophrenia, using rehabilitation
medicine models for traumatic brain injury. A number of recent
meta-analyses have demonstrated that this type of intervention
is of benefit, but numerous questions remain, including the
crucial issue of whether improvement on cognitive measures
corresponds to improvements on other tasks or to real-world
functioning. Further, there has been little analysis of individual
differences in response to cognitive remediation, despite
increasing evidence for considerable heterogeneity of cognitive
function in schizophrenia, ranging from near-normal cognitive
function to global impairment. This article will provide a
summary of the research in this area to date, and address
many of the methodological issues that are relevant in studies
on cognitive rehabilitation in schizophrenia, including a
critical review of treatment and outcome variables.
[Back to top]
Physiologic Responses in Anxiety
Rudolf Hoehn-Saric
The category “Anxiety Disorders”, as classified
in DSM-IV, includes disorders that not only differ phenomenologically
but also in their physiologic reactivity to stressor from
each other. Patients with episodic anxiety disorders, such
as phobic disorder, respond physiologically like non-anxious
individuals to everyday demands, except that they overreact
to pathology-specific stimuli. Patients with chronic anxiety
disorders, such as generalized anxiety disorder, panic disorder,
post-traumatic stress disorder and obsessive-compulsive disorder,
respond to everyday stressors with less physiologic change
than do non-anxious individuals but with strong, often excessive,
autonomic responses to pathology-specific stimuli. This article
reviews briefly the peripheral somatic response patterns of
anxiety disorders, their communalities and differences in
response to everyday stressors and to pathology-specific stressors.
Increased muscle tension, a peripheral manifestation of central
arousal, is present in all anxiety disorders during stress;
however, the contribution of the sympathetic and parasympathetic
nervous system to autonomic responses vary considerably. Moreover,
manifestations of anxiety are modified by constitutional factors
and, when present, aggravated by comorbid physical illnesses.
[Back to top]
Schizophrenia and Liver Dysfunction Caused by Portacaval
Shunting
Jens Krøll
The present review evaluates the hypothesis that a dysfunction
of the liver, caused by portacaval bypass of a normal liver,
is a predisposing factor in the pathogenesis of schizophrenia.
In support of this hypothesis was observed a more than coincidental
correlation of deviant biological findings in schizophrenia
and portacaval shunting. Deviations were observed in the expression
of neurotransmitters and neuroreceptors, metabolic parameters,
immune response and stress parameters as well as signs of
neurotoxicity with cerebral atrophy. Doppler sonographic analysis
of the portal venous system should enable a noninvasive test
of the hypothesis.
[Back to top]
Cognitive Rehabilitation for Schizophrenia: A Review
of Recent Advances
Matthew M. Kurtz and Mary C. Nichols
A critical review of randomized, controlled trials of cognitive
rehabilitation for the elementary and social cognitive deficits
characteristic of schizophrenia conducted between the years
2000-2006 was completed. Results revealed that a range of
cognitive remediation strategies typically consisting of repeated
task practice, but varying widely along dimensions of duration,
intensity, method, target of behavioral intervention, and
clinical status of participants, produced improvements on
measures of working and verbal memory, and executive-function
most commonly. There was little evidence of effects of cognitive
rehabilitation on measures of attention or positive symptoms
of schizophrenia such as delusions or hallucinations in studies
conducted between the years 2000-2006. Studies of social cognitive
remediation have revealed strong evidence for improvements
of facial affect perception deficits with even brief one-session
interventions. Two studies have shown that combining cognitive
remediation interventions with evidence-based vocational rehabilitation
and supported employment programs produce markedly superior
employment outcomes than when those same work-related interventions
are offered in the absence of remediation strategies. A variety
of approaches for future research are discussed.
[Back to top]
Transcranial Direct Current Stimulation – An
Adjuvant Tool for the Treatment of Neuropsychiatric Diseases?
Michael A. Nitsche and Felipe Fregni
Non-invasive transcranial stimulation has gained increasing
interest as a complementary treatment of neuropsychiatric
diseases. The rationale behind it is that diseases of the
central nervous system are often accompanied by pathological
cortical activity changes that can be reverted by external
cortical modulation.
Electrical stimulation with weak direct currents is a technique
to modulate cortical activity. Originally developed in the
1960s in animal experiments, it increases or decreases cortical
excitability by modulating neuronal resting membrane potential.
Phenomenological human pilot studies showed mixed results.
Technical advances have recently provided new tools to evaluate
the effects of this technique to modify cortical excitability
in humans. Newly developed protocols of transcranial direct
current stimulation (tDCS) now permit polarity-dependent cortical
excitability modulations which are induced non-invasively
and remain for over an hour after tDCS. In doing so, tDCS
modulates perceptual as well as cognitive functions in healthy
subjects, making it a potentially attractive tool for cognitive
neuroscience research. Moreover, clinical pilot studies show
that tDCS induces beneficial clinical effects in depression,
tinnitus, chronic pain, epilepsy, stroke and Parkinson´s
disease. tDCS could therefore evolve as a promising complementary
tool to treat neuropsychiatric diseases in future.
|
