Neuropsychology And~1H-MRS Research Of Apathy In Patients With Alzheimer’s Disease

[Background] Alzheimer’s disease (AD) is most commonly recognized as acognitive disorder, with memory primarily affected. However, noncognitive behavioralsymptoms are important components of the illness, contributing to both patient disabilityand caregiver stress. Apathy appears to be the most common behavioral symptom inAD. Despite high incidence of apathy and severe family and social burden, there are fewstudies about this symptom. In2009, an advanced draft was discussed at the consensusmeeting between members of the Association Franc aise de Psychiatrie Biologique, theEuropean Psychiatric Association, the European Alzheimer’s Disease Consortium andexperts from Europe, Australia and North America, and a final agreement reachedconcerning operational definitions and hierarchy of the criteria, named Diagnostic Criteriaof Apathy (DCA). It gave researchers from different countries qutie a good standard ofapathy. However, severity of apathy is not recognized properly in China, the mechanism,diagnosis, and assessment of apathy rarely reported.[Objectives] This study is aiming to investigate neuropsychological and imagingperformance as well as its possible mechanism of apathy symptoms in patients withAlzheimer’s disease. In the first section, the aim of this study is to explore thephenomenology of apathy in a series of AD participants by examining the underlyingdimensions of the behaiors and their associated clinical features.In the second section, our aim is to investigate the association between apathy andproton magnetic resonance spectroscopy (H1-MRS) measurements of different brain areasin AD patients.[Methods] In the first session, we performed a clinical cross-sectional observationalstudy by recruiting88AD patients consecutively from Department of Neurology,Changzheng Hospital from June2011to December2012. Each patient metNINCDS-ADRDA criteria for AD.(1)52apathy AD patients and36AD patients withoutapathy underwent demographic and neuropsychological testing, then compare the data of two groups in two independent samples t-test.(2) Analysis the correlation of apath withthe demographic and neuropsychological score.(3) We then took factor analysis to definespecific underlying dimensions of apathy.(4) Regression models were developed todetermine the associated NPI subscores and the der ived dimensions. The significancethreshold was set P＜0.05in all statistical tests. Analysis was carried out using Statistica16.0software.In the second session, a total of20AD patients (11with apathy and9without)underwent neuropsychological testing and single-voxel H1-MRS to measureN-acetylaspartate/creatine (NAA/Cr) and choline (Cho/Cr) ratios in cerebral regions ofinterest (ROI). We then compared the different metabolic ratios between groups andanalyzed correlations between the metabolic values and cognitive functions.[Results] In the first session, there is no significant difference in gender,age, disease of onset, duration of disease, level of education between apathy andnon-apathy AD patients (P>0.05). However, compare to non-apathic group, apathicpatients had lower overall cognitive level (P <0.01); the severity of apathy was negativelycorrelated with decline of cognitive function, especially the frontal executive function(r=-0.61, P <0.01); positively correlated with caregiverburden (r=0.66,P <0.01). AES-C scale derived two factors: cognitive-behavioral factors andsocial apathy factor, where the former is mainly associated with cognitive and sleep (R~2=0.50), the latter with depression and sleep-related (R~2=0.24).In the second session, Apathetic patients had lower NAA/Cr ratios (1.32±0.06) in theleft frontal lobe than non-apathetic subjects (1.39±0.08, P<0.05). The decline of NAA/CRwas associated with apathy severity of apathy, as well as frontal lobe executive function.[Conclusion]1、 Apathy and overall cognitive function especially executive function isclosely related which leads to a huge burden to caregivers.2、Apathy in AD patients could derive two dimension factors,and these factors areassociated with different clinical symptoms, hich may provide important cluesto the etiology of apathy. 3. These findings of the current study point to an association between apathyand frontal lobe metabolism, which may be related to impaired executivefunction. This result reaffirms the involvement of prefrontal neural circuits inAD patients with apathy.