Brain magnetic resonance spectroscopy in obsessive-compulsive disorder: the importance of considering subclinical symptoms of anxiety and depression.

Brain metabolite concentrations have recently been assessed in different cerebral regions presumably targeted in patients with obsessive-compulsive disorder (OCD) using magnetic resonance spectroscopy (MRS). However, results have been divergent. Possible confounding variables, such as the cerebral localisation of investigated regions and metabolites considered, as well as subclinical symptoms of anxiety and depression, could have affected these MRS profiles. The main goal of this study was to assess MRS metabolite differences between 13 individuals with OCD and 12 matched healthy controls in seven brain regions potentially involved in OCD. The secondary objective was to assess the relationships between levels of anxiety and depression and brain metabolite concentrations. No difference was found for N-acetylaspartate, glutamate-glutamine, myo-inositol (mI) and choline relative to creatine (Cr) concentration in either the left or right orbitofrontal area, left or right median temporal lobe, left or right thalamus or the anterior cingulate cortex. A significant negative correlation between the mI/Cr in the left orbitofrontal area and the severity of OCD symptomatology was observed while subclinical anxiety and depression were closely related to brain metabolite ratios. Thus, these subclinical symptoms, commonly associated with OCD, should be considered in assessing brain metabolite concentrations and may be central to the comprehension of this disorder.

Correlation of regional proton magnetic resonance spectroscopic metabolic changes with cognitive deficits in mild Alzheimer disease.

CONTEXT: The staging of Alzheimer disease (AD) dementia could be improved by a neurometabolic analysis using magnetic resonance spectroscopy. OBJECTIVE: To examine the correlation between regional cerebral metabolic alterations measured by proton magnetic resonance spectroscopy and neuropsychological dysfunctions in patients with early AD. DESIGN: A case-control study. SETTING: University hospital neurology clinic and radiology department. PARTICIPANTS: A cohort of 14 patients with mild AD and 14 control subjects paired for age and sex. INTERVENTIONS: Single-voxel proton magnetic resonance spectroscopic brain examination (60 minutes) and a comprehensive battery of psychometric tests (2 hours). MAIN OUTCOME MEASURES: Metabolite ratios relative to unsuppressed water were calculated for magnetic resonance spectroscopic metabolites (N-acetylaspartate, choline, creatine-phosphocreatine, and myo-inositol) in the medial temporal lobes (MTLs), parietotemporal cortices (PTCs), and frontal cortices of both hemispheres. Correlations were examined between metabolic changes in an area and psychometric scores of its known regional function: MTL and verbal memory, PTC and language and visuoconstructional abilities, and frontal cortices and executive functions. RESULTS: A significant reduction of N-acetylaspartate/water (H2O) in the left MTL and of choline/H2O in both MTLs, as well as a significant increase of myo-inositol/H2O in the right PTC were observed. Metabolic alterations in the left MTL were correlated with a loss of verbal memory, in the left PTC with language impairment, and in the right PTC with a loss of visuoconstructional abilities in the group with AD. CONCLUSION: These findings are consistent with regional distribution of neuropathologic changes and cognitive symptoms characterizing early phases of AD, and with the pattern of lateralization of normal brain function.

Similar 1H magnetic resonance spectroscopic metabolic pattern in the medial temporal lobes of patients with mild cognitive impairment and Alzheimer disease.

Structures of the medial temporal lobes are recognized to play a central role in memory processing and to be the primary sites of deterioration in Alzheimer disease (AD). Mild cognitive impairment (MCI) represents potentially an intermediate state between normal aging and AD. Proton magnetic resonance spectroscopy (MRS) was used to examine brain metabolic changes in patients with AD and MCI in the medial temporal lobes (MTLs), parietotemporal cortices (PTCs) and prefrontal cortices (PFCs). Fourteen patients with MCI, 14 patients with mild AD and 14 age- and sex-matched control subjects were studied. Patients with AD and MCI demonstrated significant reductions of NAA/H(2)O and Cho/H(2)O in the left MTL relative to control subjects. Patients with AD showed mI/H(2)O increases relative to patients with MCI and control subjects in all six regions investigated, and a statistically significant mI/H(2)O increase was measured in the right PTC. Patients with AD and MCI demonstrated the same metabolic pattern in the left MTL, suggesting a similar pathological process underlying memory impairment. Increased mI signal appears to be a neurochemical abnormality associated mostly with AD and the dementia process. Some interhemispheric metabolite asymmetries were increased in AD patients.

[Are non-literal language comprehension deficits related to a theory of mind deficit in Parkinson's disease?]. / Les déficits de compréhension du langage non littéral dans la maladie de Parkinson sont-ils liés à un déficit de la théorie de l'esprit ?

Theory of mind (TOM), i.e. the capacity to attribute mental states to oneself and others, would be impaired in Parkinson's disease (PD). Nonliteral language (NLL) comprehension would also be impaired in this disease. The goal of this study was to verify the presence of an association between the TOM and NLL comprehension deficits. We assessed 15 individuals in the early stages of PD and 17 healthy controls (HC), comparable on gender, age and education. Each subject completed a TOM evaluation task and a NLL task (i.e. metaphor comprehension). They also completed executive functioning (mental flexibility, inhibition and working memory) evaluation tasks. Our results showed that patients with PD had significant difficulties in the TOM and NLL comprehension tasks compared to HC participants. A significant relationship was found between TOM and NLL comprehension results. Moreover, NLL scores were associated with a task evaluating mental flexibility. Thus, PD might cause both TOM and NLL comprehension deficit even in the early stages of the disease. Our results showed that there would be a close relationship between TOM and NLL in people with PD.

The role of basal ganglia in language production: evidence from Parkinson's disease.

According to the dominant view in the literature, basal ganglia do not play a direct role in language but are involved in cognitive control required by linguistic and non-linguistic processing. In Parkinson's disease, basal ganglia impairment leads to motor symptoms and language deficits; those affecting the production of verbs have been frequently explored. According to a controversial theory, basal ganglia play a specific role in the conjugation of regular verbs as compared to irregular verbs. We report the results of 15 patients with Parkinson's disease in experimental conjugation tasks. They performed below healthy controls but their performance did not differ for regular and irregular verbs. These results confirm that basal ganglia are involved in language processing but do not play a specific role in verb production.

Executive functions and the obsessive-compulsive disorder: on the importance of subclinical symptoms and other concomitant factors.

Although reviews concerning the neuropsychology of obsessive-compulsive disorder (OCD) put great emphasis on impaired executive functioning, the overall conclusions are notoriously divergent. The main goal of the present study was to use a battery of neuropsychological tasks to assess nine cognitive domains with a special focus on executive functions in 40 patients with OCD. A secondary objective was to examine the relationships between clinical or demographic variables and neuropsychological performances. The third goal was to separate executive functions in more homogeneous components to verify whether specific impairment might be found in persons with OCD. Confirming the main hypothesis, few neuropsychological differences emerged between the OCD and healthy participants when concomitant factors were controlled. Moreover, subclinical symptoms appeared to play a different and independent role on the cognitive results. Future studies should include more specific tasks of lower-order executive functions among persons with OCD to confirm this possibility.