Compare and Contrast the Pathological Features of Alzheimer’s Disease and Pick’s Disease
Dementia has devastating effects on the central nervous system and is one of the most commonly encountered disorders in clinical neurology. The epidemiological of the most common dementia, Alzheimer’s disease, has long been known. However, retrospective autopsy studies have revealed that there are an increasing number of diseases that are responsible for dementia in addition to Alzheimer’s. Picks disease is a type of dementia that can be pathologically and clinically separated from Alzheimer’s, but it is often challenging to delineate the two due to numerous overlapping clinical and pathological ...view middle of the document...
In comparison, these behaviours are relatively infrequent in Alzheimer’s disease. Mendez et al (1993) reported that 76% of Pick’s patients had early personality change compared with only 31% of Alheimer’s patients. Contrastingly, Alzheimer’s patients commonly present with progressive memory loss, first of recent memory and then of more remote memory, highlighting the involvement of the hippocampus in disease pathology. In comparison, episodic memory is spared in Pick’s disease until relatively late in the disease course, with mathematical and visuospatial skills commonly well preserved. Even patients with advanced disease score well on the mini-mental state examination compared to AD (Folstein et al, 1975). However, in advance stages both disorders exhibit memory impairments that are characteristic of dementia.
Another apparent difference is that early language impairment is seen in PiD that is out of proportion with impairments in other cognitive abilities. Although language is also impaired in AD, it usually occurs later in the disease course when there is also widespread cerebral dysfunction (Wechsler et al, 1982). This also demonstrates the more severe involvement of left hemisphere in PiD compared to AD. However, within clinical settings the ability to differentiate the disorders based on contrasting symptoms is challenging as symptoms in both disorders are highly variable, depending upon the location of the cortical atrophy.
The widely accepted view that Pick’s is too similar to Alzheimer’s disease to be reliable differentiated has inspired scientists to use modern technology in order to aid diagnosis. Computed tomographic and magnetic resonance imaging have shown that one of the cardinal features of Pick’s disease is circumscribed cortical atrophy, usually affecting the frontal and temporal lobes. Scans also show prominent widening of sulcal spaces in both the frontal and temporal lobes and the peri-Sylvian region. Often pathological changes are asymmetrical, whereby structural alterations are seen on one side more than the other (Munoz-Garcia & Ludwin,1984), with atrophy more commonly worse in the dominant hemisphere (usually the left). Sparing of occipital regions, parietal regions and the posterior two-thirds of the superior temporal gyrus is common (Dickson, 2001).
MRI studies of AD show global cerebral atrophy, predominantly affecting the temporal and parietal lobes early in disease progression. Atrophy of gyri and widening of sulci of the cerebral hemispheres is also evident. Atrophy is most apparent in the medial temporal lobe, particularly localised to the parahippocampal gyrus. The occipital lobe and motor cortex are generally spared.
Imaging techniques clearly show that in both disorders the cortex becomes shrunken or atrophied and is reduced in volume. However, in contrast to AD in which the atrophy is relatively diffuse and mild, the changes seen in PiD are usually more circumscribed and are...