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In first-episode schizophrenia, longer duration of untreated psychosis (DUP) predicts poorer outcomes.
To address whether the relationship between DUP and outcome is a direct causal one or the result of association between symptoms and/or cognitive functioning and social functioning at the same time point.
Symptoms, social function and cognitive function were assessed in 98 patients with first-episode schizphrenia at presentation and 1 year later.
There was no significant clinical difference between participants with short and long DUP at presentation. Linear regression analyses revealed that longer DUP significantly predicted more severe positive and negative symptoms and poorer social function at 1 year, independent of scores at presentation. Path analyses revealed independent direct relationships between DUP and social function, core negative symptoms and positive symptoms. There was no significant association between DUP and cognition.
Longer DUP predicts poor social function independently of symptoms. The findings underline the importance of taking account of the phenomenological overlap between measures of negative symptoms and social function when investigating the effects of DUP.
Substance use may be a risk factor for the onset of schizophrenia.
To examine the association between substance use and age at onset in a UK, inner-city sample of people with recent-onset schizophrenia.
The study sample consisted of 152 people recruited to the West London First-Episode Schizophrenia Study. Self-reported data on drug and alcohol use, as well as information on age at onset of psychosis, were collected. Mental state, cognition (IQ, memory and executive function) and social function were also assessed.
In total, 60% of the participants were smokers, 27% reported a history of problems with alcohol use, 35% reported current substance use (not including alcohol), and 68% reported lifetime substance use (cannabis and psychostimulants were most commonly used). Cannabis use and gender had independent effects on age at onset of psychosis, after adjusting for alcohol misuse and use of other drugs.
The strong association between self-reported cannabis use and earlier onset of psychosis provides further evidence that schizophrenia may be precipitated by cannabis use and/or that the early onset of symptoms is a risk factor for cannabis use.
Studies of chronic schizophrenia suggest that there are subgroups with different profiles of cognitive impairment.
To determine whether such heterogeneity is present at illness onset and any relationship to clinical variables.
Ninety-three community patients with first-episode schizophrenia and 50 healthy volunteers were assessed for premorbid (Revised National Adult Reading Test) and current IQ, memory and executive function.
Half of those with schizophrenia had preserved IQ in the normal range but there was evidence of a specific impairment in spatial working memory even in those with high/average IQ; 37 out of 93 (40%) had generalised cognitive decline. Those with low premorbid IQ were significantly younger at illness onset. For the entire group, age at onset correlated positively with premorbid but not current IQ.
At illness onset, cognitive heterogeneity is present in people with schizophrenia, with a high proportion having undergone general cognitive decline. However, working memory impairment may be a common feature. Lower premorbid IQ is a risk factor for an earlier onset.
Many studies have demonstrated early generalised cognitive impairment in schizophrenia.
To examine executive function in first-episode schizophrenia, characterise the nature of the impairment and specify any relationships with symptoms and duration of untreated psychosis (DUP).
Patients (n=136) and normal controls (n=81) were assessed with the Cambridge Automated Neuropsychological Test Battery, National Adult Reading Test IQ, and Scales for the Assessment of Positive and Negative Symptoms.
Memory and executive impairments in patients were independent of IQ level. Spatial working memory was impaired because of inadequate strategy use. On a planning task, patients showed reduced planning times and suboptimal problem-solving. On an attentional set-shifting task, 75% of patients were able to perform an extra-dimensional shift thought to be a core attribute of prefrontal cortex function. Those who failed had significantly longer DUP.
Prefrontal cortex function deteriorates at the onset of psychosis and continues to worsen over time.
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