As cognitive and behavioral performance progressively deteriorate, it becomes increasingly difficult to differentiate Pick's disease from other cortical dementias such as Alzheimer's disease and necessitates neuropathology confirmation (Arnold, Hyman, & Van Hoesen, 1994). Pick's disease causes extensive atrophy and gliosis throughout the frontal lobe and anterior temporal lobe, most prominent in cortical layer three. Pick bodies are most evident in the insula and inferior temporal cortex. Loss of hippocampal dentate gyrus granular neurons with relatively preserved pyramidal neurons is characteristic of Pick's disease, while in Alzheimer's disease there is early loss of hippocampal pyramidal neurons with preservation of the dentate gyrus neurons. Nearly three fourths of Pick's disease patients display early personality changes and behaviors such as roaming, hyperorality, and disinhibition, while less than one third of Alzheimer's disease patients have such symptoms. These behaviors correlate with the greater frontal and temporal lobe damage in Pick's disease.
In addition to the clinical overlap of Pick's disease with Alzheimer's disease, the neuropathologic features of Pick's disease overlap with those of frontal lobe dementia, primary progressive aphasia, corticobasal degeneration, and multisystem atrophy. Therefore, attempts have been made to differentiate Pick's disease from progressive supranu-clear palsy and corticobasal degeneration (Feany, Mattiace, & Dickson, 1996). All three disorders have abnormalities of cortical and subcortical regions; however, Pick's disease has more cortical involvement, progressive supranuclear palsy has more subcortical damage, and corticobasal degeneration has equal cortical and subcortical pathology. The three disorders all have significant pathology in the substantia nigra, subthalamic nucleus, and locus ceruleus. However, Pick's disease has greater numbers of ballooned neurons than the other diseases; corticobasal degeneration can be distinguished by numerous neuropil threads in gray and white matter and neurofibrillary tangles in the globus pal-lidus; and progressive supranuclear palsy has numerous tangles in the globus pallidus with few neuropil threads or ballooned neurons. Thus, although there are significant overlaps, neuropathologic changes are relatively distinct for each disorder, suggesting separate pathophysiologic entities. Because of the neuropathologic similarities, these latter disorders have been grouped together under the heading "Pick's complex."
More recently, however, Pick's disease has become subsumed under the rubric of frontotemporal dementia in order to reflect the distribution of the pathologic changes rather than the exact histological subtypes of dementias. Three clinical subtypes of frontotemporal dementia are now recognized by the scientific and medical community: fronto-temporal dementia, of which a portion of cases are pathologically confirmed as Pick's disease; semantic dementia; and progressive nonfluent or primary progressive aphasia (Neary et al., 1998).
Arnold, S. E., Hyman, B. T., & Van Hoesen, G. W. V. (1994). Neuropathologic changes of the temporal pole in Alzheimer's disease and Pick's disease. Archives of Neurology, 51, 145-150. Braak, E., Arai, K., & Braak H. (1999). Cerebellar involvement in Pick's disease: Affliction of mossy fibers, monodendritic brush cells, and dentate projection neurons. Experimental Neurology, 159, 153-163.
Dickson, D. W. (1998). Pick's disease: A modern approach. Brain
Pathology, 8, 339-354. Feany, M. B., Mattiace, L. A., & Dickson, D. W. (1996). Neu-ropathologic overlap of progressive supranuclear palsy, Pick's disease and corticobasal degeneration. Journal of Neuropathology and Experimental Neurology, 55, 53-67. Giannakopoulos, P., Hof, P. R., Savioz, A., Guimon, J., Antonarakis, S. E., & Bouras, C. (1996). Early-onset dementia: Clinical, neuropathological and genetic characteristics. Acta Neuro-pathologica, 91, 451-465. Hansen, L. (1994). Pathology of the other dementia. In R. D. Terry,
R. Katzman, & L. Bick (Eds.), Alzheimer disease (pp. 167-177). New York: Raven.
Hodges, J. R. (1994). Pick's disease. In A. Burns & R. Levy (Eds.), Dementia (pp.739-752). London: Chapman & Hall.
Hodges, J. R. (2000). Pick's disease: its relationship to progressive aphasia, semantic dementia, and frontotemporal dementia. In J. O'Brien, D. Ames, & A. Burns (Eds.), Dementia (pp. 747-758). London: Edward Arnold.
Hof, P. R., Bouras, C., Perl, D. P., & Morrison, J. H. (1994). Quantitative neuropathologic analysis of Pick's disease cases: Cortical distribution of Pick bodies and coexistence with Alzheimer's disease. Acta Neuropathologica, 87, 115-124.
Mendez, M. F., Selwood, A., Mastri, A. R., & Frey, W. H. (1993). Pick's disease versus Alzheimer's disease: Acomparison of clinical characteristics. Neurology, 43, 289-292.
Mendez, M. F., Cherrier, M., Perryman, K. M., Pachana, N., Miller, B. L., & Cummings, J. L. (1996). Frontotemporal dementia versus Alzheimer's disease: Differential cognitive features. Neurology, 47, 1189-1194.
Neary D., Snowden, J. S., Gustafson, L., Passant, U., Stuff, D., et al. (1998). Frontotemporal lobar degeneration: A consensus on clinical diagnostic criteria. Neurology, 51, 1546-1554.
Tissot, R., Constantinidis, J., & Richard, J. (1985). Pick's disease. Handbook of Clinical Neurology, 2, 233-246.
Julie A. Testa University of Oklahoma Health Sciences Center
Was this article helpful?