Developmental transitions to psychopathology: are there prodromes of substance use disorders?

One of the conceptual difficulties faced by developmental psychopathologists is the plethora of terms for ‘things that predate the full manifestation of a psychiatric disorder.’ We have causes, vulnerabilities, susceptibilities, antecedents, risk factors, exposures, precursors, sub-threshold syndromes, and, of course, prodromes, the subject of this Annual Review. So we must first be clear what the word ‘prodrome’ means, and how it differs from other terms for predictors. Merriam-Webster’s dictionary defines a ‘prodrome’ as a ‘premonitory symptom of disease,’ and ‘premonitory’ as ‘giving warning.’ Conflating these two, we define a prodrome as a ‘symptom or sign that gives warning that a disease is present prior to the full manifestation of that disease.’ A review of medical dictionaries on the web shows consistent references to a prodrome as ‘An early symptom indicating the onset of an attack or disease’; ‘a premonitory clinical sign; a clinical sign indicating the onset of a disease’; ‘a symptom, often noted prior to monitoring and diagnosis that may signal the beginning of a disease’, or ‘the earliest phase of a developing condition or disease’(http://medical-dictionary.thefreedictionary.com). Wikipedia provides an example: ‘... a prodrome is an early non-specific symptom (or set of symptoms) that might indicate the start of a disease before specific symptoms occur. For example fever, malaise, headache and anorexia (lack of desire to eat) frequently occur in the prodrome of many infective disorders’. There is an important objection to the ‘non-specificity’ clause in the Wikipedia definition, because there are some highly specific prodromes. We are thinking here of, for instance, the auras of migraine and epilepsy. In both cases, these are actually symptoms of the pathological process underlying the disorders that appear before the most characteristic and florid symptoms (headaches and seizures respectively), but that sometimes occur without those more florid symptoms following. Indeed, medication in the aural phase of migraine is used to preempt the headaches. An intermediate example is the ‘bulls-eye’ rash of Lyme disease, which may or may not be observed in its characteristic form prior to the onset of the full disease. Interest in prodromes of psychiatric disorders has been revived recently by work to intervene at the prodromal phase of first-onset psychosis (reviewed in (Olsen & Rosenbaum, 2006). The key point here is that a prodrome is consistently defined as a manifestation of the disease itself, but non-specificity is not a necessary part of the definition of a prodrome.