CLINICAL CASE | 79-Year-Old Man With Memory Impairment
A 79-year-old man has become forgetful, often misplacing items at home, and sometimes is confused when paying for his groceries. His family reports that his forgetfulness seems to be getting worse. On neurological examination, he reports the correct date and knows where he is and why he is there; he has normal speech. However, he is unable to recall three unrelated words 5 minutes after correctly repeating them. When asked to perform simple addition and subtraction, he is slow and has difficulty. His mental status was further evaluated by neuropsychological testing, which revealed additional cognitive impairments.
Magnetic resonance images (MRIs) of the patient and a healthy control are presented (Figure 1–1A 1–4, B1–4). In these images, which were obtained using a particular MRI protocol termed T1 weighting, white and gray matter of the brain appear as different shades of gray and cerebrospinal fluid, black. Cranial fatty substances (eg, in skin and the bony orbits) are white. Note how the ventricles, which are fluid-filled cavities, are thin in the healthy brain (right column), but dilated in the brain of the patient (left column). Note also how the gray and white matter are both thick in the healthy brain and thinner in the patient’s brain. The hippocampal formation (Figures 1–1A4, B4, 1–10A; see Chapter 16) also is atrophic in the patient’s brain. The generalized cortical atrophy and ventricular enlargement are also apparent on the other MRIs.
The patient died several years later after developing severe dementia. At autopsy, his brain was found to show clear evidence of degeneration compared with the brain from a healthy person (A5, B5). The gyri of the cerebral cortex are narrow, and the sulci are widened. By contrast, the external characteristics of the brain stem and cerebellum were unremarkable.
You should try to answer the following questions based on your reading of the chapter and inspection of the images. Note that the description of key neurological signs that follow the questions also will provide the answers.
1. Why is the ventricular system affected, even though it is a non-neuronal structure?
2. Are some brain areas more severely affected than others in the patient?
3. Among the various brain regions affected by the neuropathological process, which is most closely associated with the patient’s memory impairment?
4. Autopsy revealed that the density of acetylcholine-containing neurons in a part of the forebrain was severely reduced in the patient. What impact might this have on the function of cortical neurons?
5. At autopsy it was discovered that the patient had large accumulations of amyloid plaques, which contain beta amyloid protein, as well as neurofibrillary tangles, which consist of an abnormal form of the microtubule-associated protein tau. What is the significance of these neuropathological findings?
The patient had Alzheimer disease, which is a neurodegenerative disease. The disease produced profound impairments of cognition, including memory disturbances, ...