A thesis submitted in partial fulfilment of - Queen Margaret University

maintenance of permanent records of information) and retrieval (employing the
previous stages to create a representation of the memory) (Parkin, 2001;
Robertson, 1999).
Purdy (2002) reports that communication impairment in people with post-stroke
aphasia may also involve executive function difficulties. While it is generally
thought that executive functions exist mainly in the frontal lobe regions of the
brain, they are supplied by the middle cerebral artery a common locus of stroke
(Callahan, 2001). Glosser and Goodglass (1990) reported that people with
aphasia present with executive impairments particularly evidenced by the
presence of perseverative errors. Purdy (2002) suggests that people with
aphasia demonstrate reduced executive abilities by being unable to initiate,
plan, monitor and correct their own communicative performance. The effects of
executive dysfunction may interact with or amplify communication limitations due
to aphasia, further limiting the ability to communicate (Keil and Kaszniak, 2002).
In fact it has been suggested that these functions may be fundamental in the
complex task of communication, which involves sequencing, monitoring,
(Ramsburger, 2000), problem solving and goal orientation (Helm-Estabrooks,
2002).
Additionally, there is a strong relationship between depression and cognitive
processes, with depression causing reversible cognitive impairment (Spalletta et
al. 2002; Kimura, Robinson and Kosier, 2000; Kauhanen et al., 1999; House,
Dennis, Warlow, Hawton, and Molyneaux, 1990) (see section 2.6.3.2). Bolla-
Wilson et al. (1989) demonstrated that left hemisphere stroke patients with
major depression had significantly greater cognitive impairments than people
with left hemisphere lesions but no depression. The cognitive processes likely to
be impaired are memory, non-verbal problem solving, attention and
psychomotor speed (Kauhanen et al., 1999). Anxiety disorder was found not to
effect cognitive processes, however people with depression and anxiety had
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