Forskningsartikler

Background: Odor identification (OI) ability is a suggested early biomarker of Alzheimer’s disease. In this study, we investigated brain activity within the brain’s olfactory network associated with OI in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer’s dementia (mAD) to uncover the neuronal basis of this impairment.
Materials and Methods: Patients with aMCI (n = 11) or mAD (n = 6) and 28 healthy older adults underwent OI functional MRI (fMRI) at 3T, OI, odor discrimination, and cognitive tests and apolipoprotein-e4 (APOE4) genotyping. Eleven patients had cerebrospinal fluid (CSF) analyzed. Those with aMCI were followed for 2 years to examine conversion to dementia.
Results: The aMCI/mAD group performed significantly worse on all OI tests and the odor discrimination test compared to controls. The aMCI/mAD group had reduced activation in the right anterior piriform cortex compared to the controls during OI fMRI [Gaussian random field (GRF) corrected cluster threshold, p < 0.05]. This group difference remained after correcting for age, sex education, and brain parenchymal fraction. This difference in piriform activity was driven primarily by differences in odor discrimination ability and to a lesser extent by OI ability. There was no group by odor discrimination/identification score interaction on brain activity. Across both groups, only odor discrimination score was significantly associated with brain activity located to the right piriform cortex. Brain activity during OI was not associated with Mini Mental Status Examination scores. At the group level, the aMCI/mAD group activated only the anterior insula, while the control group had significant activation within all regions of the olfactory network during OI fMRI. There was no association between brain activity during OI fMRI and total beta-amyloid levels in the CSF in the aMCI/mAD group.
Conclusion: The OI impairment in aMCI/mAD patients is associated with significantly reduced activity in the piriform cortex compared to controls. Activation of downstream regions within the olfactory network is also significantly affected in the aMCI/mAD group, except the anterior insula, which is impinged late in the course of Alzheimer’s disease. OI tests thus reflect Alzheimer’s disease pathology in olfactory brain structures.

Grete Kjelvik, Hallvard R. Evensmoen, Thomas Hummel, Knut Engedal, Geir Selbæk, Ingvild Saltvedt and Asta K. Håberg.

Abstract:
Responsive identity support in conversations with people with dementia: A study of interviews in a five-years narrative longitudinal study A narrative longitudinal study depends on trust and a positive relationship between the  interviewer and the  participant to encourage  the  participant’s continued participation. In reported studies, the methodological part is usually too short to present the complexities in dialogues over time. We therefore have analyzed the interview processes with younger people with dementia, relating the interactions to central  concepts associated with identity.

The aim was to explore the methodological interview approach used in a longitudinal study, focusing on supporting identity and self-esteem. We used the concept of responsive identity to illuminate our findings. In addition, we demonstrate how the interview dialogues can support identity and self-esteem of the participants. The core of this approach is that  the interviewee, living with dementia, should be seen, confirmed and supported to preserve the person`s self and dignity. Dialogue with responsive identity support is a fruitful research method in dementia research. This approach can be generalized to person-centred communication in health and caring relationships.

Kirsten Thorsen og Aud Johannessen

Abstract: The deviation between chronological age and age predicted using brain MRI is a putative marker of overall brain health. Age prediction based on structural MRI data shows high accuracy in common brain disorders. However, brain aging is complex and heterogenous, both in terms of individual differences and the underlying biological processes. Here, we implemented a multimodal model to estimate brain age using different combinations of cortical area, thickness and sub-cortical volumes, cortical and subcortical T1/T2-weighted ratios, and cerebral blood flow (CBF) based on arterial spin labeling. For each of the 11 models we assessed the age prediction accuracy in healthy controls (HC, n = 750) and compared the obtained brain age gaps (BAGs) between age-matched subsets of HC and patients with Alzheimer’s disease (AD, n = 54), mild (MCI, n = 90) and subjective (SCI, n = 56) cognitive impairment, schizophrenia spectrum (SZ, n = 159) and bipolar disorder (BD, n = 135). We found highest age prediction accuracy in HC when integrating all modalities. Furthermore, two-group case-control classifications revealed highest accuracy for AD using global T1-weighted BAG, while MCI, SCI, BD and SZ showed strongest effects in CBF-based BAGs. Combining multiple MRI modalities improves brain age prediction and reveals distinct deviations in patients with psychiatric and neurological disorders. The multimodal BAG was most accurate in predicting age in HC, while group differences between patients and HC were often larger for BAGs based on single modalities. These findings indicate that multidimensional neuroimaging of patients may provide a brain-based mapping of overlapping and distinct pathophysiology in common disorders.

Jaroslav Rokicki, Thomas Wolfers, Wibeke Nordhøy, Natalia Tesli, Daniel S Quintana, Dag Alnaes, Genevieve Richard, Ann-Marie G de Lange, Martina J Lund, Linn Norbom, Ingrid Agartz, Ingrid Melle, Terje Naerland, Geir Selbaek, Karin Persson, Jan Egil Nordvik, Emanuel Schwarz, Ole A Andreassen, Tobias Kaufmann, Lars T Westlye.