The Lewy body, the hallucination, the atrophy and the physiology

Sir, Recent publication of Whitwell et al. (2007) in Brain offers a useful addition to our understanding of dementia with Lewy bodies (DLB). In a very large n study, they offer the most definitive evidence yet published of what previous studies have been hinting at in recent years; this being that cortical atrophy, particularly when compared to Alzheimer's disease (AD), is not a major feature of DLB. In contradistinction to a well-matched sample of AD patients, they found minimal cortical involvement in DLB and argued, very plausibly, that where atrophy was identified it could simply be a reflection of concomitant AD pathology. However, when discussing their findings with respect to visual hallucination they make the following comment: The specific structural locus of visual hallucinations is, however, unclear. Authors have suggested that deficits in the NBM (Perry and Perry, 1995; Josephs et al. , 2006), or midbrain may be critical (Manford and Andermann, 1998; Josephs et al. , 2006). Cortical regions have also been implicated (Imamura et al. , 1999; Harding et al. , 2002; Mori et …