Psychological alterations in Alzheimer's and Parkinson's disease: A comparison of cortical and subcortical dementia

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Bonnie Levin - Committee Chair

Second Committee Member

Patrice Saab - Committee Member


A substantial proportion of Alzheimer's disease (AD) and Parkinson's disease (PD) patients experience concomitant psychopathology at some time during their illness. The dementia syndromes associated with these two diseases have been relatively well established, yet few studies have directly compared the noncognitive aspects of these two dementias. This descriptive study set out to determine whether or not these neuropathologically different dementia syndromes produced distinct patterns of psychological disturbance. In the present study, 30 mildly demented AD and 31 mildly demented PD subjects were compared on the following domains: awareness of cognitive deficits, affective disturbance (depression and anxiety), optimism, obsessive-compulsivity, and paranoid/psychotic thinking. Thirty-one healthy elderly adults and 25 nondemented PD patients served as control subjects.Results revealed that subjects in the AD group were significantly different from subjects in the PD group in every psychological domain examined except for paranoid/psychotic thinking. The demented PD group, representing subcortical dermentia, was characterized as depressed, subclinically anxious, moderately obsessive-compulsive, and relatively free of paranoid/psychotic disturbance. The AD group, representing cortical dementia, was characterized by markedly impaired awareness of cognitive decline, low levels of affective distress, high levels of dispositional optimism, and a relative lack of psychotic/delusional thought. Subjects with PD were characterized by more distress than subjects with AD, though the demented PD group tended to report more distress than the nondemented PD group. Women with PD dementia were more aware of their cognitive decline and reported more obsessive-compulsive symptoms than men with PD dementia. This is the first report of gender differences in psychological aspects of PD dementia and further research is needed to clarify the issue. Findings are consistent with literature indicating that impaired awareness of cognitive deficits is common in AD and that negative affect is central to PD. This study suggests that although dementia in AD and PD may share certain neuropsychological features (e.g., impaired memory, executive function, and visuospatial skills), the concomitant psychological profiles are different. As the subjects in this study were mildly demented, the findings cannot be generalized to more severe stages of AD and PD dementias.


Health Sciences, Mental Health; Gerontology; Psychology, Physiological

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