Essay --

There is compelling inference that cognitive dysfunction is inherent to Parkinsons disease (PD) (Aarsland et al. 2003 Aarsland et al. 2007a Aarsland et al. 2010a). Clinical manifestations of cognitive deterioration in PD range from slight deficits -only demonstrable by means of comprehensive neuropsychological testing - up to dementia (Muslimovic et al. 2005 Aarsland et al. 2009 Foltynie et al. 2004).From the soonest stages of the disease, including drug-nave subjects, patients suffering from PD may show cognitive impairment (CI). This eject be restricted to a single domain or affects ten-fold cognitive domains (Muslimovic et al. 2005 Foltynie et al. 2004). Based on recent longitudinal studies, there is slightly evidence suggesting that, along the evolution of the disease, a subgroup of patients presenting defects on distinct cognitive domains will eventually deteriorate to the point of dementia associated to PD (PDD) (Aarsland et al. 2003 Buter et al. 2008 Hely et al. 2008 Emre et al. 2007). scratch line on a similar theoretical approach than those used for MCI in Alzheimers disease (AD) -where early cognitive deterioration linearly submit to dementia- (Petersen et al. 2001a Petersen et al. 2001b) an operative redefinition of the construct of MCI in PD has been proposed to identify and diagnose these initial cognitive deficits as early indicators of PDD (Caviness et al. 2007).Historically, MCI has been considered as the transitional stage amongst normality to dementia, based on the measurable presence of cognitive dysfunctions in single or multiple cognitive domains without concurring disabilities on activities of fooling living (Petersen 2004). MCI in AD usually follows a linear improvement from subtle deficits to dementia (... ...mild cognitive impairment to dementia in PD patients is characterized by the addition of cortical-type cognitive deficits atop a prominent and modernized frontal-striatal dysfunction. Besides the search for biomarkers, a usefulness definition and development of diagnostic criteria for PD-MCI, should consider to (i) delimitate the heterogeneous cognitive deficit of PD and how we give the axe accurately assess it in large sample of PD subjects (ii) put in with prospective studies whether the prognostic value of the severity and the nature of the cognitive deficits (iii) come a consensus of the minimum of cognitive tasks and instruments to assess cognition in PD and finally, (iv) delimitate the role played by common PD-related neuropsychiatric features such(prenominal) apathy or visual hallucinations as early markers of dementia in absence of evident neuropsychological impairment.