Aboulia: neurobehavioural dysfunction of dopaminergic system?

Dissociating behavioral disorders in early dementia-An FDG-PET study

Behavioral impairments occur frequently in dementia. Studies with magnetic resonance imaging, measuring atrophy, have systematically investigated their neural correlates. Such a systematic approach has not yet been applied to imaging with [(18)F] fluorodeoxyglucose positron emission tomography (FDG-PET), although regional hypometabolism may precede and exceed atrophy in dementia. The present study related all behavioral disorders as assessed with the Neuropsychiatric Inventory to reductions in brain glucose utilization as measured by FDG-PET with Statistical Parametric Mapping (SPM5). It included 54 subjects mainly with early Alzheimer's disease, frontotemporal lobar degeneration, and subjective cognitive impairment. Apathy, disinhibition and eating disorders - most frequent in frontotemporal lobar degeneration - correlated significantly with regional brain hypometabolism. Whereas a single regressor analysis and conjunction analysis revealed largely overlapping frontomedian regions that were associated with all three behavioral domains, a disjunction analysis identified three specific neural networks for each behavioral disorder, independent of dementia severity. Apathy was related to the ventral tegmental area, a component of the motivational dopaminergic network; disinhibition to both anterior temporal lobes including the anterior hippocampi and left amygdala, caudate head, orbitofrontal cortex and insulae; and eating disorders to the right lateral (orbito) frontal cortex/insula. Our study contributes to the understanding of behavioral deficits in early dementia and suggests specific diagnostic and therapeutic approaches.

Neurocognitive functioning in women presenting with undifferentiated somatoform disorders in Oman

AIM

There is a dearth of research from non-Western populations focusing on neurocognitive functioning in patients presenting with undifferentiated somatoform disorders. The aim of the present quest is to examine the presence of cognitive impairment and other health-related parameters among attendees at psychiatric settings in Oman, an Arab/Islamic country, with a diagnosis of undifferentiated somatoform disorder.

METHOD

In order to compare the performance of patients diagnosed with undifferentiated somatoform disorder (n = 20) and normal healthy subjects (n = 18) on indices of attention and concentration, tests of executive functioning, mood, somatization and vegetative functioning were carried out.

RESULTS

The performance of patients with undifferentiated somatoform disorder differed from that of normal healthy subjects on the presently operationalized indices of working memory and executive functioning, anxiety, quality of sleep and psychosomatically expressed psychological distress.

CONCLUSION

To our knowledge, this is the first study highlighting neurocognitive functioning in patients with undifferentiated somatoform disorders from a non-Western population. This type of study has the potential of shedding light on the covariates of such a debilitating and intransigent condition as undifferentiated somatoform disorder.

Traumatic brain injury affects the frontomedian cortex--an event-related fMRI study on evaluative judgments

Traumatic brain injuries represent the leading cause of death and disability in young adults in industrialized countries. Recently, it has been suggested that dysfunctions of the frontomedian cortex, which enables social cognition, are responsible for clinical deficits in the long-term. To validate this hypothesis, we examined brain activation in seven young adults suffering from diffuse axonal injury during a cognitive task that specifically depends on frontomedian structures, namely evaluative judgments, contrasted with semantic memory retrieval. Brain activation in patients was compared with healthy age and gender matched control subjects using event-related functional magnetic resonance imaging. Evaluative judgments were related to a neural network discussed in the context of self-referential processing and theory of mind. More precisely, the neural network consisted of frontomedian regions, the temporal pole, and the posterior superior temporal gyrus and sulcus/angular gyrus. Patients showed higher activations in this network and the inferior frontal gyrus, whereas healthy control subjects activated more dopaminergic structures, namely the ventral tegmental area, during evaluative judgments. One possible interpretation of the data is that deficits in the ventral tegmental area, and consequently the mesocorticolimbic projection system, have to be compensated for by higher brain activations in the frontomedian and anterior cingulate cortex in patients with diffuse axonal injury. In conclusion, our study supports the hypothesis that traumatic brain injury is characterized by frontomedian dysfunctions, which may be responsible for clinical deficits in the long-term and which might be modified by rehabilitative strategies in the future.

Neurobiology: venom of wasps and initiation of movements

The ability to initiate movements can be impaired in some brain injuries even though motor actions proceed normally once they are begun. The effects of venom that wasps use in preying upon cockroaches could provide insights into this problem.

[The French concept of "Athymhormie" (Loss of vital force) from 1922 to the present]

The psychiatric concept of athymhormie (loss of vital force "élan vital" and affectivity) was developed at the beginning of the 20th century and used exclusively in France, until it was fortunately adopted by mostly French-speaking neurologists. The authors of the concept, M Dide and P Guiraud, considered the term an independent entity, an heir to dementia praecox, for which they did not like to substitute a "schizophrenia" with blurry boundaries. This term then came to mean to them, and to most French psychiatrists to this day, the basic core of psychosis' deficient forms. The word athymhormie (or loss of psychic self-activation) is now also used in neurology for the behavioural and emotional consequences of lesions caused on basal nuclei and, more widely, of a circuit associated with the limbic loop. However, the phenomenological reality of the associated disorders and the relevance of the same name can be questioned. This review concludes that although the settings--in a psychiatric or a neurologic clinic--where athymhormie takes place are very different, the choice of the same name is justified in a renewed and symptomatic neuropsychiatric approach. The objective of this approach is to explore why some symptoms, common or similar, could represent the lack of a physiological function, presumed here to be motivation.