{'fraction_non_alphanumeric': 0.026856240126382307, 'fraction_numerical': 0.00315955766192733, 'mean_word_length': 5.364321608040201, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Letters to the editor

Davidson and Weiser (1) have highlighted the rationale for and the substantial potential benefits linked to early recognition and optimal treatment of psychotic disorders, specifically schizophrenia. Their excellent review would have been enhanced by explicit consideration of the prodrome concept, an essential element in formulating early intervention strategies for serious mental disorders. For schizophrenia, and other disorders too, it is presumed that a degree of biopsychosocial vulnerability is created on the basis of genetic make-up and/or the accumulation of environmental risk factors operating during the perinatal period and perhaps beyond this. The most typical pattern subsequently is a latent or quiescent period during which, in some people, there may be subtle, non-specific biobehavioural markers of this vulnerability. This is the ‘premorbid’ phase. From early adolescence onwards, at a variable point in time, a second phase can be identified, presumably now an active phase of disorder, during which subtle symptoms and cognitive changes accumulate which steadily give rise to more substantial and pervasive disability, even before frank positive psychotic symptoms manifest. If there is progression to psychosis, this phase can be retrospectively termed the ‘prodromal’ phase. The psychosocial disability which builds up during this phase usually sets a ceiling for ultimate recovery, even where there is a complete remission of positive symptoms with neuroleptic treatment of the first psychotic episode (2). Obviously, delays in ensuring treatment of the first episode are another key secondary preventive focus, as is the quality and extent of this mix of interventions (3). In my opinion, with our present level of knowledge, attempting to focus on the premorbid or ‘vulnerable’ phase prior to the onset of prodromal change will be too inefficient and potentially harmful, unless a broad range of disorders are targeted via very non-specific psychosocial interventions. Conversely, more specific interventions can be focused on the late prodromal/prepsychotic phase (termed by our group ‘at risk mental state’ (4)), yet even here there is a finite false positive rate (5, 6). Using a sequential screening or ‘close in’ intervention strategy (7) of this kind is likely to be more costeffective, as well as ethically safer, than the much broader screening approach proposed by the authors. It may be possible to blend these approaches within a broader youth mental health focus (8).