Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Attention deficit hyperactivity disorder (ADHD) comprises a deficit in behavioral inhibition. A theoretical model is constructed that links inhibition to 4 executive neuropsychological functions that appear to depend on it for their effective execution: (a) working memory, (b) self-regulation of affect-motivation-arousal, (c) internalization of speech, and (d) reconstitution (behavioral analysis and synthesis). Extended to ADHD, the model predicts that ADHD should be associated with secondary impairments in these 4 executive abilities and the motor control they afford. The author reviews evidence for each of these domains of functioning and finds it to be strongest for deficits in behavioral inhibition, working memory, regulation of motivation, and motor control in those with ADHD. Although the model is promising as a potential theory of self-control and ADHD, far more research is required to evaluate its merits and the many predictions it makes about ADHD.

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Behavioral inhibition, sustained attention, and executive functions: Constructing a unifying theory of ADHD.

• Recent research on schizophrenia has demonstrated that in this disorder the brain is not, strictly speaking, normal. The findings suggest that nonspecific histopathology exists in the limbic system, diencephalon, and prefrontal cortex, that the pathology occurs early in development, and that the causative process is inactive long before the diagnosis is made. If these findings are valid and not epiphenomena, then the pathogenesis of schizophrenia does not appear to fit either traditional metabolic, posttraumatic, or neurodegenerative models of adult mental illness. The data are more consistent with a neurodevelopmental model in which a fixed "lesion" from early in life interacts with normal brain maturational events that occur much later. Based on neuro-ontological principles and insights from animal research about normal brain development, it is proposed that the appearance of diagnostic symptoms is linked to the normal maturation of brain areas affected by the early developmental pathology, particularly the dorsolateral prefrontal cortex. The course of the illness and the importance of stress may be related to normal maturational aspects of dopaminergic neural systems, particularly those innervating prefrontal cortex. Some implications for future research and treatment are considered.

Implications of normal brain development for the pathogenesis of schizophrenia

The type, frequency, and extent of MR signal abnormalities in Alzheimer9s disease and normal aging are a subject of controversy. With a 1.5-MR unit we studied 12 Alzheimer patients, four subjects suffering from multiinfarct dementia and nine age-matched controls. Punctate or early confluent high-signal abnormalities in the deep white matter, noted in 60% of both Alzheimer patients and controls, were unrelated to the presence of hypertension or other vascular risk factors. A significant number of Alzheimer patients exhibited a more extensive smooth “halo” of periventricular hyperintensity when compared with controls (p = .024). Widespread deep white-matter hyperintensity (two patients) and extensive, irregular periventricular hyperintensity (three patients) were seen in multiinfarct dementia. Areas of high signal intensity affecting hippocampal and sylvian cortex were also present in five Alzheimer and two multiinfarct dementia patients, but absent in controls. Discrete, small foci of deep white-matter hyperintensity are not characteristic of Alzheimer9s disease nor do they appear to imply a vascular cause for the dementing illness. The frequently observed “halo” of periventricular hyperintensity in Alzheimer9s disease may be of diagnostic importance. High-signal abnormalities in specific cortjcal regions are likely to reflect disease processes localized to those structures.

http://www.ajnr.org/content/ajnr/8/3/421.full.pdf

MR Signal Abnormalities at 1.5 T in Alzheimer's Dementia and Normal Aging

The neurocognitive literature on test performance in schizophrenia is reviewed quantitatively. The authors report 22 mean effect sizes from 204 studies to index schizophrenia versus control differences in global and selective verbal memory, nonverbal memory, bilateral and unilateral motor performance, visual and auditory attention, general intelligence, spatial ability, executive function, language, and interhemispheric tactile-transfer test performance. Moderate to large raw effect sizes (d > .60) were obtained for all 22 neurocognitive test variables, and none of the associated confidence intervals included zero. The results indicate that schizophrenia is characterized by a broadly based cognitive impairment, with varying degrees of deficit in all ability domains measured by standard clinical tests.

Neurocognitive Deficit in Schizophrenia: A Quantitative Review of the Evidence

OBJECTIVE: Imaging studies of schizophrenia have repeatedly demonstrated global abnormalities of cerebral and ventricular volumes. However, pathological changes at more local levels of brain organization have not yet been so clearly characterized because of the few brain regions of interest heretofore included in morphometric analyses as well as heterogeneity of patient samples. METHOD: Dual echo magnetic resonance imaging (MRI) data were acquired at 1.5 T from 27 right-handed patients who met DSM-IV criteria for schizophrenia with enduring negative symptoms and from 27 healthy comparison subjects. Between-group differences in gray and white matter volume were estimated at each intracerebral voxel after registration of the images in standard space. The relationship between clinical symptom scores and brain structure was also examined within the patient group. Spatial statistics and permutation tests were used for inference. RESULTS: Significant deficits of gray matter volume in the patient group were foun...

https://ajp.psychiatryonline.org/doi/pdfplus/10.1176/appi.ajp.158.2.234

Structural abnormalities in frontal, temporal, and limbic regions and interconnecting white matter tracts in schizophrenic patients with prominent negative symptoms.

Objective: A relatively small number of functional imaging studies of attention deficit hyperactivity disorder (ADHD) have shown abnormal prefrontal and striatal brain activation during tasks of motor response inhibition. However, the potential confound of previous medication exposure has not yet been addressed, and no functional imaging study exists to date on medication-naive children and adolescents with ADHD. The aim of this study was to investigate the neural substrates of a range of motor and cognitive inhibitory functions in a relatively large group of children and adolescents with ADHD who had never previously been exposed to medication. Method: Nineteen boys with ADHD and 27 healthy age- and IQ-matched boys underwent functional MRI to compare brain activation during performance of tasks that assessed motor response inhibition (go/no go task), cognitive interference inhibition (motor Stroop task), and cognitive flexibility (switch task). Results: Boys with ADHD showed decreased activation in the l...

https://ajp.psychiatryonline.org/doi/pdf/10.1176/ajp.2006.163.6.1044

Task-Specific Hypoactivation in Prefrontal and Temporoparietal Brain Regions During Motor Inhibition and Task Switching in Medication-Naive Children and Adolescents With Attention Deficit Hyperactivity Disorder

Data from the Camberwell Collaborative Psychosis Study were used to examine the proposition that there is an excess of life events preceding the onset of psychoses of all types. Of 97 patients from the study who had episodes within the past year that were datable, 51 had developed psychotic symptoms from an essentially symptom-free state, 29 had been suffering only from neurotic symptoms, and 17 had experienced a marked exacerbation of psychotic symptoms. DSM-III diagnoses were collapsed into three major groups: 51 cases of schizophrenia; 31 cases of mania; and 14 cases of depressive psychosis. Life-event histories were taken for the six months before onset, and when these were compared with equivalent histories from a psychiatrically healthy sample from the local general population, there was a significant excess of life events, particularly in the three months before onset of psychosis. This was apparent in all groups, and remained even when events were restricted to the independent category. The excess of events began rather earlier than has been found in previous studies. In our view, this study provides some of the strongest evidence for a link between life events and the emergence of psychotic symptoms.

Life events and psychosis : initial results from the camberwell collaborative psychosis study

A follow-up study of patients diagnosed as suffering from presenile dementia has revealed a high incidence of erroneous diagnoses. Of 52 patients discharged from hospital with this diagnosis, information was obtained 5-15 years later on 51. Eighteen were alive and the diagnosis was rejected in 16 (31 per cent). Possible reasons for the mistaken diagnoses are discussed.

Diagnostic accuracy in presenile dementia.

In an investigation of the timing and precursors of social decline in schizophrenia and affective psychosis, 195 subjects from the Camberwell Collaborative Psychosis Study were currently of lower social class than were their fathers. A comparison between father's occupation and proband's best premorbid occupational level indicated underachievement confined to DSM-III schizophrenia, there being no such effect in affective psychosis. Decline in social status following onset of psychosis, analysed by comparing best premorbid occupation with current occupation, was marked in both schizophrenia and affective psychosis, indicating a non-specific effect. Schizophrenic patients who failed to achieve their fathers' social status had poorer educational qualifications than those who equalled or bettered their paternal social class, despite similar premorbid IQ (NART) scores and age at onset of psychosis. These results indicate that schizophrenia may be manifest before the onset of psychosis, and lend weight to the notion of a developmental origin to this disorder.

Brian Toone

Papers

Structural abnormalities in frontal, temporal, and limbic regions and interconnecting white matter tracts in schizophrenic patients with prominent negative symptoms.

Task-Specific Hypoactivation in Prefrontal and Temporoparietal Brain Regions During Motor Inhibition and Task Switching in Medication-Naive Children and Adolescents With Attention Deficit Hyperactivity Disorder

Life events and psychosis : initial results from the camberwell collaborative psychosis study

Diagnostic accuracy in presenile dementia.

Premorbid social underachievement in schizophrenia. Results from the Camberwell Collaborative Psychosis Study.