ABSTRACT
Neurological soft signs (NSS) include abnormalities in sensory and motor performance that are indicative of non-speci®c cerebral dysfunction (Dazzan & Murray, 2002; Grif®ths et al., 1998; Shibre et al., 2002). Early neurological studies of patients with schizophrenia showed that neurological signs could be demonstrated in the absence of a recognized underlying neurological diagnosis (Quitkin et al., 1976; Tucker et al., 1974). These studies examined a mixture of localizing neurological signs such as the plantar response, as well as tests of motor co-ordination and sensory integration. Signs demonstrated in these studies were designated `soft signs' because of the absence of known accompanying focal structural pathology. In later studies, the term `soft sign' has been used more restrictively for signs that do not suggest primary tract or nucleus pathology, as opposed to `hard signs', which do (Woods et al., 1986). The variation in the signs examined in different studies, and the use of the terms `hard' and `soft' to describe different combinations of signs, makes evaluation of previous work extremely dif®cult. Moreover, the term `soft sign' implies that the signs sought are not acceptable in classical neurology and cannot be de®ned with any rigour; this is not the case. In fact, there is now agreement that these signs are present in excess in patients with schizophrenia at the time of the ®rst psychotic episode (Dazzan & Murray, 2002). They are thought to be indicative of non-speci®c cerebral dysfunction (Dazzan & Murray, 2002;
Grif®ths et al., 1998; Shibre et al., 2002). Indeed, their presence in psychosis has been associated, even in ®rst-episode patients, with reductions of brain areas implicated in the pathogenesis of the disorder, like the association cortex and the basal ganglia (Dazzan et al., 2004; Keshavan et al., 2003).
