“…The most prominent deficits occur in the so-called frontal lobe or executive functions (Bondi et al, 1993;Cooper et al, 1991;Gotham et al, 1988;Jacobs et al, 1995) and include impaired retrieval (Auriacombe et al, 1993;Massman et al, 1990;McFadden et al, 1996;Mohr et al, 1990;Randolph et al, 1993;Tröster & Fields, 1995), processing difficulties when confronted with a situation that requires a highly effortful response (Taylor & Saint-Cyr, 1995;Weingartner et al, 1984), deficits in working memory (Dalrymple-Alford et al, 1994), abnormally rapid disengagement of attention (i.e., difficulty maintaining attention to relevant visual stimuli; Filoteo et al, 1994;Maddox et al, 1996), and an instability of cognitive set (Flowers & Robertson, 1985). Deficits in visuospatial abilities have also been demonstrated in nondemented patients with PD (Bondi et al, 1993;Levin et al, 1991;Mohr et al, 1990;Stern et al, 1993), and may be due, in part, to executive dysfunction (Bondi et al, 1993;Levin et al, 1991;Mohr et al, 1990) or to deficits in visual attention (Filoteo et al, 1994).…”