We have read with interest the study by Santangelo et al., 1 reporting the role of vascular pathology in the neuropsychological profile of parkinsonian patients. The authors evaluated whether the brain's vascular lesion load is associated with neuropsychological variables. They compared the neuropsychological profile of patients affected by Parkinsonism and vascular lesions to that of patients with Parkinson's disease (PD) without vascular lesions. The conclusion was that ''regardless of the presence of dopaminergic denervation, cerebrovascular lesions . . . have an important effect in determining early onset and severity of cognitive impairment in patients with parkinsonism''. We agree with the authors that a comorbid cerebrovascular disease (CVD) may have an important impact on impairment of cognitive functions in patients with PD. In this aspect, the PD patients are not fundamentally different from patients without Parkinsonism.
We have recently demonstrated that the pathology of vessels supplying the brain contribute to the disease severity in PD patients even without a CVD. 2 In 57 consecutive PD patients, we measured ultrasound parameters indicating an atherosclerotic disease of the large and small brain vessels. The occurrence of the MRI and clinically manifested CVD was rare (stroke or transient ischemic attack in five patients, only small volume white matter lesions), concurring with results of large epidemiological studies. 3,4 The ultrasonographic examination of extracranial vessels comprised the measurement of the intima-medial thickness (IMT) of the common carotid artery, and the carotid arteries were evaluated for the presence of atherosclerotic plaques. IMT is considered to be a useful sonographic marker of early atherosclerotic affection. Regarding the ultrasonographic examination of intracranial vessels, the resistance and pulsatility indexes (RI, PI) were calculated. These indexes are not just functions of flow resistance; they are also influenced by vascular compliance. The results of a multiple regression analysis revealed a significant association between the IMT and motor, functional, and cognitive impairment (as measured by the Hoehn-Yahr score, Lawton's Instrumental Activities of Daily Living, Barthel Index, Mini-Mental State Examination, and Clock Drawing Test -for details see Rektor et al. 2 ). Several cognitive tests (Benton Temporal Orientation Test and the Recognition subtest of the Wechsler Memory Scale III) were significantly associated with the PI.
Our results suggest a possible link between a comorbid and otherwise subclinical atherosclerotic involvement and the degree of motor and cognitive decline caused primarily by disease-related degenerative brain changes. This subclinical brain hypoperfusion may affect the severity of clinical symptoms of PD even prior to the development of CVD.