Occupation provides valuable information on premorbid ability in dementia. Not only is
occupation related to cognitive and brain reserve, but premorbid sub-symptomatic
impairment may influence prospective career choice. Frontotemporal lobar degeneration
(FTLD) patients with professions dependent upon one hemisphere have demonstrated
contralateral degeneration. The present work was the first group study to examine the
relationship between atrophy in FTLD and occupation. Chapter one reviews methods for
quantifying occupations and introduces the Occupational Information Network database.
This database provided quantified occupation attribute data and enabled subsequent
multivariate analyses. A principal component analysis yielded five factors that
parsimoniously summarized verbal, physical, mechanical, mathematical and visuospatial
occupational demands, some with hypothesized neuroanatomical substrates. Chapters two
and three tested the hypothesis that occupation characteristics systematically relate to origin of atrophy in FTLD. In a multi-centre chart review of 588 patients, occupation
information was related to location of atrophy. Patients with unilateral right atrophy had higher verbal scores than patients with unilateral left or bilateral atrophy. Thus, occupation selection occurring in early adulthood is related to lateralized brain damage in patients who develop FTLD decades later. The finding suggests that verbal occupations may have been pursued due to incipient right-hemisphere functional impairment. Alternatively, long-term engagement of verbal processes contributed to left-hemisphere reserve, right-hemisphere dysfunction, or both. In a subgroup of well-characterized patients with quantified brain imaging data, chapter three replicated and extended these findings. The lateralization effect was limited to the temporal lobes and included both
verbal and mathematical ability. This pattern may reflect shared attributes between
mathematics and language processing, which are mediated by left-temporal lobe
structures. Patients whose professions placed high demands on language had relatively
preserved left temporal lobes and atrophy originating in the right temporal lobes at
disease onset whereas patients with less challenging linguistic occupations were more
susceptible to the onset of atrophy in the left-temporal lobe. In chapter four, the
hypothesized relationship between occupational attainment and global degeneration was supported. Patients with highly skilled occupations had less atrophy than patients with lower-skilled occupations. Notably, specific occupational attributes were predictive of brain volume after controlling for demography and disease progression. Overall, a relationship between occupation and FTLD is supported.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/11265 |
| Date | 01 August 2008 |
| Creators | Spreng, Robert Nathan |
| Contributors | Levine, Brian |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
| Format | 856079 bytes, application/pdf |
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