Schizophrenia 15.2 per 10000 persons (range being 7.7 to

          Schizophrenia is one among the most studied serious psychiatric disorders.

The word ‘Schizophrenia’ is less than 100 years old. But the illness is believed to have accompanied mankind throughout the history. The documented descriptions of the illness can be dated back as early to Egyptian civilization. There has been documentation in roman and Greek literature as well. Dr. Emil Kraepelin was one of the pioneers who described this illness and termed it as ‘Dementia praecox’ as it was deemed to have deteriorating and irreversible course. Eugene Bleuler coined the term ‘Schizophrenia’ by which he meant ‘splitting of psychic functions’ which results in the illness.

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He defined a set of symptoms that were supposed to be characteristic of schizophrenia (4 As) which included Abnormal associations, autistic behaviour and thinking, abnormal affect and ambivalence.  Kurt Schneider defined first rank symptoms (FRS) as pathognomic to schizophrenia. Few of the first rank symptoms still hold importance in current diagnostic system. Over time there were different conceptualizations of the illness and this led to different diagnostic systems. International pilot study of schizophrenia (IPSS) was a ground breaking study which showed that schizophrenia manifested in similar ways across different cultures and countries(26). Currently DSM –V or ICD-10 criteria is used for the diagnosis of schizophrenia.  Kety and colleagues introduced the term Schizophrenia spectrum disorders(27). Schizoaffective disorder and schizophreniform disorder fall under this spectrum(28).

          A recent epidemiological review of schizophrenia reveals following (29) (30)(31)-       Incidence rate of 15.2 per 10000 persons (range being 7.7 to 43 per 10000).-       Higher incidence is noted with urbanicity and migration.-       Life time risk of 0.7% approximately.

–       Greater life time risk in males.-       Prevalence rate of 4 to 7 per 1000.-       Higher prevalence in lower socio-economic classes.-       Mortality rates are 2 to 3 times higher when compared to general population.-       Life time risk for suicide in schizophrenia is 5%.           Schizophrenia includes diverse set of signs and symptoms. Schizophrenia is characterized by an admixture of different symptom domains consisting of positive, negative, disorganization, cognitive, psychomotor, and mood symptoms.

?Positive symptoms are the obvious and dramatic symptoms of illness which includes delusions, hallucinations abnormalities of thought, hostility. Negative symptoms include blunted affect, alogia, asociality, avolition and anhedonia (32). Cognitive deficits also have been documented and it is being debated to be included in the diagnostic criteria. It includes deficits in attention, verbal learning and memory, working memory and executive functions (33,34).

          Auditory verbal hallucinations are the hallmark symptom of schizophrenia. They are defined as vocal perceptions in the absence of the corresponding external stimulus. They occur at sufficient similarity as real percept and most of individuals suffering from it consider them to be out of their control (35).

AVH are most prevalent in diagnosed cases of schizophrenia and schizoaffective disorder (36). But they also occur in substance intoxication, bipolar disorder and organic brain disorders. Epidemiological studies have shown that the prevalence of AVH ranges from 5 to 28% in general population (37).  Auditory hallucinations may range from elementary noises to fully formed voices. Voices may be single or multiple and may talk to or about the person. Typically the negative comments and commands from ‘voices’ , the patient may be cognitively and emotionally drained (38). This results in disorientation of reality and inward attentional focus (39). As per ‘inner speech model’, AVHs are caused by a failure to adequately acknowledge verbal thoughts as coming from the inside rather than from the outside of the individual’s head (40).

Auditory hallucinations are hallmark symptom of schizophrenia. Various neuro-imaging studies have provided the evidence that structural and functional abnormalities of brain regions involving areas of language processing, memory, emotion, insula, hippocampus, limbic area and Broca’s area (7,17,18,41,42). TPJ has been considered critical in the presence and severity of AVH (7,43). It has been found that there is hyperactivity of TPJ and reduced functional connectivity of TPJ with frontal areas and speech perception areas(7).           Antipsychotic medications are capable of inducing a rapid improvement in AVH severity.

 If there is no response to the antipsychotic agent of first choice it is probably best to switch to another antipsychotic agent at a relatively early stage. Clozapine is considered drug of first choice if other antipsychotic agents fail to act (44). Chronic auditory hallucinations which are refractory to treatment occur in 25 % of cases of schizophrenia (8). Refractory AVH leads to severe disability and impairment in quality of living. Non- pharmacological approaches include CBT and non-invasive brain stimulation and other new modalities which needs further research.

A recent meta-analysis has shown low effect size of CBT in resistant AVH (10). Non-invasive brain stimulation holds promise in this area and active research is undergoing in this particular area.