The functional neuroanatomy of social behaviour: changes in cerebral blood flow when people with autistic disorder process facial expressions

Although high-functioning individuals with autistic disorder (i.e. autism and Asperger syndrome) are of normal intelligence, they have life-long abnormalities in social communication and emotional behaviour. However, the biological basis of social difficulties in autism is poorly understood. Facial expressions help shape behaviour, and we investigated if high-functioning people with autistic disorder show neurobiological differences from controls when processing emotional facial expressions. We used functional MRI to investigate brain activity in nine adults with autistic disorder (mean age +/- standard deviation 37 +/- 7 years; IQ 102 +/- 15) and nine controls (27 +/- 7 years; IQ 116 +/- 10) when explicitly (consciously) and implicitly (unconsciously) processing emotional facial expressions. Subjects with autistic disorder differed significantly from controls in the activity of cerebellar, mesolimbic and temporal lobe cortical regions of the brain when processing facial expressions. Notably, they did not activate a cortical 'face area' when explicitly appraising expressions, or the left amygdala region and left cerebellum when implicitly processing emotional facial expressions. High-functioning people with autistic disorder have biological differences from controls when consciously and unconsciously processing facial emotions, and these differences are most likely to be neurodevelopmental in origin. This may account for some of the abnormalities in social behaviour associated with autism.

Autistic disorders and schizophrenia: related or remote? An anatomical likelihood estimation

Shared genetic and environmental risk factors have been identified for autistic spectrum disorders (ASD) and schizophrenia. Social interaction, communication, emotion processing, sensorimotor gating and executive function are disrupted in both, stimulating debate about whether these are related conditions. Brain imaging studies constitute an informative and expanding resource to determine whether brain structural phenotype of these disorders is distinct or overlapping. We aimed to synthesize existing datasets characterizing ASD and schizophrenia within a common framework, to quantify their structural similarities. In a novel modification of Anatomical Likelihood Estimation (ALE), 313 foci were extracted from 25 voxel-based studies comprising 660 participants (308 ASD, 352 first-episode schizophrenia) and 801 controls. The results revealed that, compared to controls, lower grey matter volumes within limbic-striato-thalamic circuitry were common to ASD and schizophrenia. Unique features of each disorder included lower grey matter volume in amygdala, caudate, frontal and medial gyrus for schizophrenia and putamen for autism. Thus, in terms of brain volumetrics, ASD and schizophrenia have a clear degree of overlap that may reflect shared etiological mechanisms. However, the distinctive neuroanatomy also mapped in each condition raises the question about how this is arrived in the context of common etiological pressures.

Effects of route of administration on oxytocin-induced changes in regional cerebral blood flow in humans

Could nose-to-brain pathways mediate the effects of peptides such as oxytocin (OT) on brain physiology when delivered intranasally? We address this question by contrasting two methods of intranasal administration (a standard nasal spray, and a nebulizer expected to improve OT deposition in nasal areas putatively involved in direct nose-to-brain transport) to intravenous administration in terms of effects on regional cerebral blood flow during two hours post-dosing. We demonstrate that OT-induced decreases in amygdala perfusion, a key hub of the OT central circuitry, are explained entirely by OT increases in systemic circulation following both intranasal and intravenous OT administration. Yet we also provide robust evidence confirming the validity of the intranasal route to target specific brain regions. Our work has important translational implications and demonstrates the need to carefully consider the method of administration in our efforts to engage specific central oxytocinergic targets for the treatment of neuropsychiatric disorders.

Are Bipolar Disorder and Schizophrenia Neuroanatomically Distinct? An Anatomical Likelihood Meta-analysis

Objective: There is renewed debate on whether modern diagnostic classification should adopt a dichotomous or dimensional approach to schizophrenia and bipolar disorder. This study synthesizes data from voxel-based studies of schizophrenia and bipolar disorder to estimate the extent to which these conditions have a common neuroanatomical phenotype. Methods: A post-hoc meta-analytic estimation of the extent to which bipolar disorder, schizophrenia, or both conditions contribute to brain gray matter differences compared to controls was achieved using a novel application of the conventional anatomical likelihood estimation (ALE) method. 19 schizophrenia studies (651 patients and 693 controls) were matched as closely as possible to 19 bipolar studies (540 patients and 745 controls). Result: Substantial overlaps in the regions affected by schizophrenia and bipolar disorder included regions in prefrontal cortex, thalamus, left caudate, left medial temporal lobe, and right insula. Bipolar disorder and schizophrenia jointly contributed to clusters in the right hemisphere, but schizophrenia was almost exclusively associated with additional gray matter deficits (left insula and amygdala) in the left hemisphere. Limitation: The current meta-analytic method has a number of constraints. Importantly, only studies identifying differences between controls and patient groups could be included in this analysis. Conclusion: Bipolar disorder shares many of the same brain regions as schizophrenia. However, relative to neurotypical controls, lower gray matter volume in schizophrenia is more extensive and includes the amygdala. This fresh application of ALE accommodates multiple studies in a relatively unbiased comparison. Common biological mechanisms may explain the neuroanatomical overlap between these major disorders, but explaining why brain differences are more extensive in schizophrenia remains challenging.

Cognitive enhancers in theory and practice: studies of the cholinergic hypothesis of cognitive deficits in Alzheimer's disease

The current status of the cholinergic hypothesis of cognitive dysfunction in Alzheimer's disease is reviewed in the context of recent attempts to alleviate specific cognitive impairments produced in rats by excitotoxic lesions of basal forebrain neurons by treatment with cholinergic agents. AMPA-induced lesions of the nucleus basalis region in rats produce profound and relatively specific reductions in neocortical markers of cholinergic function but fail to affect performance in many tests of memory and learning in rats. However, such lesions produce specific deficits in responding accurately in a test of visual attentional performance, which are reversed dose-dependently by treatment with systemic physostigmine or nicotine. Analogous improvements have been reported in a clinical trial of the anticholinesterase tacrine in patients with Alzheimer's disease. By contrast, AMPA-induced lesions of the medial septum produce profound reductions in hippocampal acetylcholine and accompanying delay-dependent deficits in a delayed non-matching-to-position procedure which measures spatial working memory in rats. This impairment is shown to be reversed to some extent by treatment with low doses of physostigmine. The results are discussed in terms of the multivariate nature of the neurochemical pathology of Alzheimer's disease and attendant limitations in the use of the cholinergic strategy. The cognitive costs, as well as benefits, of cognitive enhancers are discussed, as well as the need to broaden our therapeutic approach to other neurotransmitter systems and other neurodegenerative disorders.

Brain morphometry volume in autistic spectrum disorder: a magnetic resonance imaging study of adults

BACKGROUND

Several prior reports have found that some young children with autism spectrum disorder [ASD; including autism and Asperger's syndrome and pervasive developmental disorder - not otherwise specified (PDD-NOS)] have a significant increase in head size and brain weight. However, the findings from older children and adults with ASD are inconsistent. This may reflect the relatively small sample sizes that were studied, clinical heterogeneity, or age-related brain differences.

METHOD

Hence, we measured head size (intracranial volume), and the bulk volume of ventricular and peripheral cerebrospinal fluid (CSF), lobar brain, and cerebellum in 114 people with ASD and 60 controls aged between 18 and 58 years. The ASD sample included 80 people with Asperger's syndrome, 28 with autism and six with PDD-NOS.

RESULTS

There was no significant between-group difference in head and/or lobar brain matter volume. However, compared with controls, each ASD subgroup had a significantly smaller cerebellar volume, and a significantly larger volume of peripheral CSF.

CONCLUSIONS

Within ASD adults, the bulk volume of cerebellum is reduced irrespective of diagnostic subcategory. Also the significant increase in peripheral CSF may reflect differences in cortical maturation and/or ageing.

MRI predicts remission at 1 year in first-episode schizophrenia in females with larger striato-thalamic volumes

BACKGROUND/AIMS

The Remission in Schizophrenia Working Group has defined remission as 'a low-mild symptom intensity level, maintained for a minimum of 6 months, where such symptoms do not affect an individual's behaviour' [Andreasen et al.: Am J Psychiatry 2005;162:441-449]. Since brain morphology relates to symptomatology, treatment and illness progression, MRI may assist in predicting remission.

METHODS

Thirty-nine patients newly diagnosed with DSM-IV schizophrenia underwent MRI brain scan prior to antipsychotic exposure. The Global Assessment of Functioning (GAF) score was entered into a voxel-based analysis to evaluate its relationship with cerebral grey matter volume from the baseline MRI. We entered age, total intracranial volume and intake GAF score as co-variates. Males and females were analysed separately because gender is a potent determinant of outcome.

RESULTS

Males had lower GAF scores than females, both at intake and at 1 year. Males comprised only 40% (12 out of 39) of the early remission group. For females only, early remission was strongly and positively correlated with bilateral lentiform and striatal volumes. For males, there was no such relationship.

CONCLUSION

Larger striato-thalamic volume correlated with early remission in females only. These baseline MRI findings were unlikely to be confounded by antipsychotic treatment and chronicity. These brain morphological markers show gender dimorphism and may assist in the prediction of early remission in newly diagnosed schizophrenia.

Fronto-parietal white matter microstructural deficits are linked to performance IQ in a first-episode schizophrenia Han Chinese sample

BACKGROUND

Evidence shows that cognitive deficits and white matter (WM) dysconnectivity can independently be associated with clinical manifestations in schizophrenia. It is important to explore this triadic relationship in order to investigate whether the triplet could serve as potential extended endophenotypes of schizophrenia.

METHOD

Diffusion tensor images and clinical performances were evaluated in 122 individuals with first-episode schizophrenia and 122 age- and gender-matched controls. In addition, 65 of 122 of the patient group and 40 of 122 controls were measured using intelligence quotient (IQ) testing.

RESULTS

The schizophrenia group showed lower fractional anisotropy (FA) values than controls in the right cerebral frontal lobar sub-gyral (RFSG) WM. The schizophrenia group also showed a significant positive correlation between FA in the RFSG and performance IQ (PIQ) ; in turn, their PIQ score showed a significant negative correlation with negative syndromes.

CONCLUSIONS

Overall, these findings support the hypothesis that WM deficits may be a core deficit that contributes to cognitive deficits as well as to negative symptoms.