***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background The relationship between apathy , depression and cognitive impairment in Parkinson 's disease ( PD ) is still controversial . The objective of this study is to investigate whether apathy and depression are associated with inefficient cognitive strategies in PD . Methods In this prospect i ve clinical cohort study conducted in a university-based clinical and research movement disorders center we studied 48 PD patients . Based on clinical evaluation , they were classified in two groups : PD with apathy ( PD-A group , n = 23 ) and PD without apathy ( PD-NA group , n = 25 ) . Patients received clinical and neuropsychological evaluations . The clinical evaluation included :  Apathy Evaluation Scale-patient version , Hamilton Depression Rating Scale-17 items , the Unified Parkinson 's Disease Rating Scale and the Hoehn and Yahr staging system ; the neuropsychological evaluation explored speed information processing , attention , working memory , executive function , learning abilities and memory , which included several measures of recall ( immediate free , short delay free , long delay free and cued , and total recall ) . Findings PD-A and PD-NA groups did not differ in age , disease duration , treatment , and motor condition , but differed in recall ( p<0.001 ) and executive tasks ( p<0.001 ) . Immediate free recall had the highest predictive value for apathy ( F = 10.94 ; p = 0.002 ) . Depression and apathy had a weak correlation ( Pearson index = 0.3 ; p<0.07 ) , with three items of the depression scale correlating with apathy ( Pearson index between .3 and .4 ; p<0.04 ) . The depressed and non-depressed PD patients within the non-apathetic group did not differ . Conclusion Apathy , but not depression , is associated with deficit in implementing efficient cognitive strategies . As the implementation of efficient strategies relies on the fronto-striatal circuit , we conclude that apathy , unlike depression , is an early expression of executive impairment in PD Objective : Apathy may be induced by subthalamic nucleus deep brain stimulation ( STN-DBS ) in Parkinson disease ( PD ) . We therefore wished to test the hypothesis that apathy induced by STN-DBS correlates with changes in glucose metabolism , using 18FDG-PET . Methods : Twelve patients with PD were assessed 3 months before ( M−3 ) and 3 months after ( M+3 ) STN-DBS with 18FDG-PET and the Apathy Evaluation Scale . Results : Apathy had significantly worsened at M+3 after STN-DBS . Positive correlations were observed between this variation in apathy scores and changes in glucose metabolism , especially in the right frontal middle gyrus ( Brodmann area [ BA ] 10 ) and right inferior frontal gyrus ( BA 46 and BA 47 ) . Negative correlations between the two were observed in the right posterior cingulate gyrus ( BA 31 ) and left medial frontal lobe ( BA 9 ) . Conclusion : These preliminary results confirm the role of the subthalamic nucleus in associative and limbic circuitry in humans and suggest that it is a key basal ganglia structure in motivation circuitry This study investigated the cerebral correlates of the Trail Making Test ( TMT ) , used commonly as a measure of frontal lobe function . Such work sheds additional light on the known shortcomings of the TMT as a localizing instrument , as indicated , for example , by studies of patients with focal brain lesions .  Functional magnetic resonance imaging ( fMRI ) was used to record brain activity while participants performed the  TMT  using a custom-built , fiber-optic fMRI-compatible writing device , the " virtual stylus " . Unlike in a previous fMRI study that used a verbal adaptation of the TMT , the virtual stylus enabled a closer depiction of the brain regions engaged by the actual paper- and -pencil task . Twelve , right-h and ed healthy young adults participated . In Part A of the task , participants were required to link in ascending order numbers ( 1 - 2 - 3 ... ) that were r and omly distributed on a computer screen . In Part B , participants were required to link alternately between numbers and letters ( 1-A-2-B ... ) . Although behavioral performance was somewhat less than typically obtained with the TMT due to use of the virtual stylus , distinct left-sided dorsolateral and medial frontal activity was revealed when comparing Part B versus Part A. These findings agree with existing literature showing sensitivity of the TMT  to frontal regions in the left hemisphere . However , other activity was also observed ( left middle and superior temporal gyrus ) reinforcing that the brain-behavior correlations for the TMT are multifaceted and not restricted to the frontal lobe BACKGROUND Hallucinations are a frequent and severe complication in Parkinson 's disease ( PD ) . Minor hallucinations are generally not disturbing , but likely progress to well-structured hallucinations with loss of insight and a great impact on quality of life . Knowledge on the neural bases of minor hallucinations may help to describe those systems associated with the early development of psychotic phenomena in PD . In this study , we aim ed to identify the pattern of structural brain alterations associated with minor hallucinations in PD by using voxel-based morphometry ( VBM ) . METHODS We prospect ively collected a sample of 46 non-demented PD patients , with ( N = 17 ) and without ( n = 29 ) minor hallucinations ( passage and /or presence hallucinations ) , and 15 healthy controls . Groups were matched for age , education and global cognitive function . Presence and type of minor psychotic phenomena was assessed by the new MDS-UPDRS . Three dimensional T1-weighted MRI images were acquired with a 1.5 T magnet , and analyzed using optimized VBM . RESULTS Compared to controls , PD with minor hallucinations ( PD-mH ) showed reduced gray matter volume bilaterally in different areas of the dorsal visual stream , and in functionally related midbrain and cerebellar structures . Additionally , bilateral gray matter volume increases were observed in the PD-mH group in limbic and paralimbic regions . CONCLUSIONS Our data support a major role of the dorsal visual stream in the genesis of minor hallucinations in PD , reinforcing the importance of posterior cortical regions for the development of cognitive and psychiatric complications in PD OBJECTIVE This study is a pilot validation of the  Executive Interview ( EXIT ) , a novel instrument design ed to assess executive cognitive function ( ECF ) at the bedside . DESIGN Inter-rater reliability testing and validation using inter-group comparisons across levels of care and measures of cognition and behavior . PARTICIPANTS Forty elderly subjects r and omly selected across four levels of care . SETTING Setting s ranged from independent living apartments to design ated Alzheimer 's Special Care units in a single 537-bed retirement community . MEASUREMENTS The EXIT : a 10-minute , 25-item interview scored from 0 - 50 ( higher scores = greater executive dyscontrol ) was administered by a physician . Subjects were also administered the  Mini-Mental State Exam ( MMSE ) and traditional tests of " frontal " executive function by a neuropsychologist , and the Nursing Home Behavior Problem Scale ( NHBPS ) by Licensed Vocational Nurses . RESULTS Interrater reliability was high ( r = .90 ) . EXIT scores correlated well with other measures of ECF . The interview discriminated among residents at each level of care . In contrast , the MMSE did not discriminate apartment-dwelling from residential care residents , or residential care from nursing home residents . The EXIT was highly correlated with disruptive behaviors as measured by the NHBPS ( r = .79 ) . CONCLUSIONS These preliminary findings suggest that the EXIT is a valid and reliable instrument for the assessment of executive impairment at the bedside . It correlates well with level of care and problem behavior . It discriminates residents at earlier stages of cognitive impairment than the MMSE The objective of this study was to define risk factors for depression in patients with idiopathic Parkinson 's disease ( PD ) and to evaluate the correlation of depression with cognitive function and the primary domains of parkinsonian motor dysfunction tremor , bradykinesia , rigidity , gait and balance impairment . The risk factors for depression in patients with PD remain controversial . Several investigators have demonstrated a significant association between cognitive dysfunction and depression , but motoric and disease variables can confound this evaluation and have shown an inconsistent relation to depression . A consecutive series of 88 patients with PD were examined using the  motor subscale of the Unified Parkinson 's Disease Rating Scale ( UPDRSm ) , Hoehn-Yahr stage ( HY )  , and Hamilton Rating Scale for Depression ( HRSD ) . Major depression was diagnosed according to the criteria in the Diagnostic and Statistic Manual of Mental Disorders , 4th edition . Gender , age , h and edness , PD duration , side of PD onset , motor fluctuations , UPDRSm total score , daily Levodopa dose , and Mini-Mental State Examination score ( MMSE ) were analyzed using multivariate and univariate logistic regression , Fisher 's Exact test , and Pearson correlations . Major depression was diagnosed in 12 patients ( 7.3 % ) . Low MMSE score , axial bradykinesia , gait and balance impairment were strongly significant predictors of depression . In conclusion , depression and physical function are important factors impairing the quality of life for patients with PD , and regular depression screening and treatment should focus on patients with PD who have cognitive impairment , high axial bradykinesia , gait and balance impairment The authors investigated neuropsychiatric symptoms in  mild cognitive impairment ( MCI ) from baseline data of the Investigation in the Delay to Diagnosis of AD with Exelon ( InDDEx ) study ( n = 1,010 ) . Neuropsychiatric symptoms were reported in 59 % of subjects ( Neuropsychiatric Inventory [ NPI ] ) . NPI+ subjects had significantly greater impairment on global , cognitive , and functional scores than NPI− subjects . The presence of neuropsychiatric symptoms appears to be a marker of MCI severity 
    Output:
    
RESULTS The main findings revealed that executive dysfunctions were common in patients with depression , apathy , visual hallucinations ( VH ) , impulse control disorders ( ICDs ) and anxiety , whereas , memory deficits were associated mainly with depression and VH .
Imaging studies have shown that frontal lobe atrophy was frequently observed in patients with depression , apathy , VH and ICDs .
This review gives a snapshot of those cognitive and neural correlates of neuropsychiatric symptoms in PD .
Method ological shortcoming in the available studies were identified , however , of which the most critical appeared neglecting the presence of multiple neuropsychiatric symptoms in some of the patients included in studies of specific individual symptoms .