| 1. |
- Laukka, Erika J., et al.
(author)
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Associations between White Matter Microstructure and Cognitive Performance in Old and Very Old Age
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:11
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Journal article (peer-reviewed)abstract
- Increasing age is associated with deficits in a wide range of cognitive domains as well as with structural brain changes. Recent studies using diffusion tensor imaging (DTI) have shown that microstructural integrity of white matter is associated with cognitive performance in elderly persons, especially on tests that rely on perceptual speed. We used structural equation modeling to investigate associations between white matter microstructure and cognitive functions in a population-based sample of elderly persons (age >= 60 years), free of dementia, stroke, and neurological disorders (n = 253). Participants underwent a magnetic resonance imaging scan, from which mean fractional anisotropy (FA) and mean diffusivity (MD) of seven white matter tracts were quantified. Cognitive functioning was analyzed according to performance in five task domains (perceptual speed, episodic memory, semantic memory, letter fluency, and category fluency). After controlling for age, FA and MD were exclusively related to perceptual speed. When further stratifying the sample into two age groups, the associations were reliable in the old-old (>= 78 years) only. This relationship between white matter microstructure and perceptual speed remained significant after excluding persons in a preclinical dementia phase. The observed pattern of results suggests that microstructural white matter integrity may be especially important to perceptual speed among very old adults.
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| 2. |
- Liberg, Benny, et al.
(author)
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Motor imagery in bipolar depression with slowed movement.
- 2013
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In: The Journal of nervous and mental disease. - 1539-736X. ; 201:10, s. 885-93
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Journal article (peer-reviewed)abstract
- We hypothesized that motor retardation in bipolar depression is mediated by disruption of the pre-executive stages of motor production. We used functional magnetic resonance imaging to investigate neural activity during motor imagery and motor execution to elucidate whether brain regions that mediate planning, preparation, and control of movement are activated differently in subjects with bipolar depression (n = 9) compared with healthy controls (n = 12). We found significant between-group differences. During motor imagery, the patients activated the posterior medial parietal cortex, the posterior cingulate cortex, the premotor cortex, the prefrontal cortex, and the frontal poles more than the controls did. Activation in the brain areas involved in motor selection, planning, and preparation was altered. In addition, limbic and prefrontal regions associated with self-reference and the default mode network were altered during motor imagery in bipolar depression with motor retardation.
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| 3. |
- Lövdén, Martin, et al.
(author)
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The dimensionality of between-person differences in white matter microstructure in old age
- 2013
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In: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 34:6, s. 1386-1398
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Journal article (peer-reviewed)abstract
- Between-person differences in white matter microstructure may partly generalize across the brain and partly play out differently for distinct tracts. We used diffusion-tensor imaging and structural equation modeling to investigate this issue in a sample of 260 adults aged 60–87 years. Mean fractional anisotropy and mean diffusivity of seven white matter tracts in each hemisphere were quantified. Results showed good fit of a model positing that individual differences in white matter microstructure are structured according to tracts. A general factor, although accounting for variance in the measures, did not adequately represent the individual differences. This indicates the presence of a substantial amount of tract-specific individual differences in white matter microstructure. In addition, individual differences are to a varying degree shared between tracts, indicating that general factors also affect white matter microstructure. Age-related differences in white matter microstructure were present for all tracts. Correlations among tract factors did not generally increase as a function of age, suggesting that aging is not a process with homogenous effects on white matter microstructure across the brain. These findings highlight the need for future research to examine whether relations between white matter microstructure and diverse outcomes are specific or general. Hum Brain Mapp, 2012. © 2012 Wiley Periodicals, Inc.
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| 4. |
- Howner, Katarina, et al.
(author)
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Brain processing of fearful facial expression in mentally disordered offenders
- 2011
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In: Journal of Behavioral and Brain Science. - Irvine, CA : Scientific Research Publishing. - 2160-5866 .- 2160-5874. ; 1:3, s. 115-123
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Journal article (peer-reviewed)abstract
- Emotional facial expressions are important cues for interaction between people. The aim of the present study was to investigate brain function when processing fearful facial expressions in offenders with two psychiatric disorders which include impaired emotional facial perception; autism spectrum disorder (ASD) and psychopathy (PSY). Fourteen offenders undergoing forensic psychiatric assessment (7 with ASD, and 7 psychopathic offenders) and 12 healthy controls (HC) viewed fearful and neutral faces while undergoing functional magnetic resonance imaging (fMRI). Brain activity (fearful versus neutral faces) was compared both between HC and offenders and between the two offender groups (PSY and ASD). Functional co-activation was also investigated. The offenders had increased activity bilaterally in amygdala and medial cingulate cortex as well as the left hippocampus during processing fearful facial expressions compared to HC. The two subgroups of offenders differed in five regions compared with each other. Results from functional co-activation analysis suggested a strong correlation between the amygdala and anterior cingulate cortex (ACC) in the left hemisphere only in the PSY group. These findings suggest enhanced neural processing of fearful faces in the amygdala as well as in other facial processing brain areas in offenders compared to HC. Moreover, the co-activation between amygdala and ACC in the PSY but not the ASD group suggested qualitative differences in amygdala activity in the two groups. Since the sample size is small the study should be regarded as a pilot study.
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| 5. |
- Howner, Katarina, et al.
(author)
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Thinner cortex in the frontal lobes in mentally disordered offenders
- 2012
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In: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123 .- 0925-4927. ; 203:2-3, s. 126-131
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Journal article (peer-reviewed)abstract
- Antisocial and violent behaviour have been associated with both structural and functional brain abnormalities in the frontal and the temporal lobes. The aim of the present study was to assess cortical thickness in offenders undergoing forensic psychiatric assessments, one group with psychopathy (PSY, n = 7) and one group with autism spectrum disorder (ASD, n = 7) compared to each other as well as to a reference group consisting of healthy non-criminal subjects (RG, n = 12). A second aim was to assess correlation between scores on a psychopathy checklist (PCL-SV) and cortical thickness. Magnetic resonance imaging (MRI) and surface-based cortical segmentation were used to calculate cortical thickness. Analyses used both regions of interest and statistical maps. When the two groups of offenders were compared, there were no differences in cortical thickness, but the PSY group had thinner cortex in the temporal lobes and in the whole right hemisphere compared to RG. There were no differences in cortical thickness between the ASD group and RG. Across subjects there was a negative correlation between PCL-SV scores and cortical thickness in the temporal lobes and the whole right hemisphere. The findings indicate that thinner cortex in the temporal lobes is present in psychopathic offenders and that these regions are important for the expression of psychopathy. However, whether thinner temporal cortex is a cause or a consequence of the antisocial behaviour is still unknown.
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| 6. |
- Huang, Chaorui, et al.
(author)
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Voxel- and VOI-based analysis of SPECT CBF in relation to clinical and psychological heterogeneity of mild cognitive impairment.
- 2003
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In: NeuroImage. - 1053-8119. ; 19:3, s. 1137-1144
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Journal article (peer-reviewed)abstract
- This study aimed to explore the heterogeneity of mild cognitive impairment (MCI) and detect differences in regional cerebral blood flow (rCBF) and cognitive function between progressive mild cognitive impairment (PMCI) and stable mild cognitive impairment (SMCI) in order to identify specific changes useful for early diagnosis of dementia. SPECT was performed in 82 MCI subjects and 20 controls using Tc-99m hexamethylpropyleneamine oxime. Cognitive functions were tested in five domains which included episodic memory, semantic memory, visuospatial function, attention, and general cognitive function. After the initial examination, MCI subjects were clinically followed for an average of 2 years. Twenty-eight subjects progressed to dementia and were defined as PMCI at baseline and 54 subjects remained stable and were defined as SMCI at baseline. The baseline rCBF and cognitive function of PMCI, SMCI, and controls were compared. PMCI had decreased relative rCBF in the parietal lobes and increased relative rCBF in prefrontal cortex compared to SMCI and controls at baseline. The cognitive function of PMCI was more severely impaired compared to SMCI with respect to episodic memory and visuospatial and general cognitive function. Both SPECT and neuropsychological tests had moderate discriminant function between PMCI and SMCI at baseline with the area under the receiver operating characteristic (ROC) curve at 75–77%. The combination of these two methods improved the diagnostic accuracy with the area under the ROC curve at 82–84%. Semantic memory and attention were negatively correlated with left prefrontal relative rCBF among the study population. The results show that the clinical heterogeneity of MCI is reflected in different patterns of psychological and CBF changes. Combined SPECT investigation and neuropsychological testing might predict the future development of dementia in patients with MCI.
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