Neuropsychological Deficits in Initial Parkinson’s Disease

Parkinson's disease (PD), is a neurodegenerative illness, producing movement disorders, although it is also associated to cognitive deficit and emotional and behavioral alterations (Fuiza & Mayán, 2005; Vera-Cuesta et al., 2006), being prominent the presence of neuropsychological deficits among the majority of PD patients. The neuropsychological disorders can be observed from the very initial phases of the illness, nevertheless, the results obtained from studies of these deficits are often confusing and little clear. These contradictory results are due to diverse factors, which mainly are: the heterogeneity of the samples used in the studies, the absence of consensus during the tests and to the lack of clarity at the time of using diverse terms as specific cognitive alterations, mild cognitive impairment and dementia. During the last years there is an increased interest in studying and describing cognitive deficit associated with PD (Aarsland et al., 2003; Giannaula, 2010; Locascio, Corkin & Growdon, 2003; Ostrosky-Solís, 2000; Perea-Bartolomé, 2001; Weintraub et al., 2004). This interest is justified if keeping numbers in mind. It is saying, the totality of PD patients show alterations from initial phases in tasks requiring attention, visuospatial, mnesic o executive functions. Also, about 20% to 30% of the patients with PD reach dementia along the evolution of the illness (Caixeta & Vieira, 2008; Halvorsen & Tynes, 2007; Hilker et al, 2005). It has been emphasized in diverse studies that the diagnosis of dementia in PD is often underestimated (Caixeta & Vieira, 2008; Halvorsen & Tynes, 2007; Hobson & Meara, 2004). Therefore, long term studies to be carried out with such patients will be needed in order to evaluate the type and scope of cognitive deficit associated with the PD. Caviness et al. (2007) carried out a study among 86 patients, showing the presence of signs of cognitive deterioration. In particular, they found that 62% of the participants were cognitive intactly, 21% were fulfilling criteria of mild cognitive impairment and only 17% had symptoms compatible with dementia according to DSM IV. The study results also proved that patients with mild cognitive impairment were characterized for having, principally, executive deficit and alterations of memory, especially in tasks of free delayed memory and working memory. Therefore, the above mentioned study emphasizes the need to detect signs of cognitive deterioration in PD patients from the very beginning of the illness, that is to say, to detect the early neuropsychological deficits, and to supervise the evolution and course of these cognitive deficits.