The Neuropsychology of de Novo Patients with Idiopathic Parkinson's Disease: The Effects of Age of Onset

Abstract

One hundred de novo patients with Parkinson's disease (PD) were classified into two groups according to age of onset of symptoms. Seventy two patients were under 70 years and 28 were 70 years and over. All patients were given neurological and neuropsychological assessments, and the severity of the signs was rated on a modified Columbia scale. The neuropsychological assessment was also administered to 50 age-and-education-matched controls. The neuropsychological test battery included tests of verbal learning, visual memory, verbal fluency, visuospatial skill, simple and choice reaction time, language and maze learning. The late-onset patients had significant impairment in nonverbal reasoning, auditory verbal learning, visual memory and choice reaction time in contrast to early-onset patients and controls. A relationship was found between bradykinesia and widespread cognitive impairment. Severity of tremor was found to be significantly correlated with impairment in auditory verbal learning, visual memory and increased choice reaction time, while rigidity was found to be associated with cognitive impairment in verbal fluency and visuospatial skill. Using DSM II criteria, 39% of the late-onset and 8% of the early-onset group were classified as demented. Dementia was more common in patients with bilateral symmetrical disease and in those patients with marked tremor and bradykinesia. The pattern of cognitive impairment in PD was consistent with that associated with a subcortical dementia. This study confirms that the expression of PD is markedly influenced by the age of onset.

Regional Brain Atrophy in Idiopathic Parkinson's Disease and Diffuse Lewy Body Disease

“…Frontal lobe dysfunction in PD dementia has been documented in many clinical studies, although both the clinical signs and degree of atrophy differ significantly from that occurring in the frontotemporal degenerative dementias [34,35], Frontal deficits in PD are often more marked in older patients [4,25,36], and mild or absent in nondemented PD patients [1,37], The mild frontal lobe atrophy noted in our late-onset PD cases may be the ana tomical substrate for such a difference. The late-onset PD cases had significant cortical plaque pathology compared with controls and middle-age-onset cases but were with out cortical neuronal pathology.…”

“…The size of this volume loss therefore may be underestimated when the cross-sectional area of one or a few slices are measured [30,40], Hippocampal loss associ ated with memory impairment has been demonstrated in nondemented aged patients [43], In addition, all patients with PD are impaired in spatial working memory, regard less of medication or the presence or absence of dementia [44], These observations suggest that a reduced hippo campal volume may contribute to memory dysfunction. A reduced performance in tasks requiring verbal memory or visuospatial, sequencing and temporal ordering skills arc also characteristic of PD [4,5,8,25,[45][46][47][48]. These defi cits appear to be common to all parkinsonian groups and may also be associated with the loss of hippocampal vol ume.…”

“…The topography and severity of nigral cell loss was equivalent in all PD cases [ 18], As participants of our brain donor program for PD research, all cases were prospectively studied during the course of their disease [23,24] with regular assessment of neuropsychological abilities. Details of the neuropsychological testing procedures have been previously reported [3,25], with impairment in memory and at least two other areas of cognitive functioning required for a diagnosis of dementia (table 2). For comparison, age-and sex-matched controls without neurological or neuropathological abnormalities were col lected with consent at routine hospital autopsy (n = 13; table 1).…”

Executive functions and disease characteristics in Parkinson's disease

“…Most studies dealing with the relationship of cognitive dysfunction and other disease characteristics in non demented patients with Parkinson's disease (PD) found a rather scattered pattern of associations between single test performance and motor symptoms [39,42,46]. This pattern may result from the fact that these studies aimed at a large variety of tests in order to cover a great diversity of cognitive functions and also from the heterogeneity of the patients under study.…”

The Role of Cholinergic Deficiency in Neuropsychological Deficits in Idiopathic Parkinson's Disease

“…Reassessment after 3 years showed that no significant improvement in neuropsychological test scores resulted from treatment with levodopa or bromocriptine [3]. These results suggest that replacement of DA does not improve cognitive functioning despite improving the mo tor symptoms of PD.…”