**Question:** Good prognostic factor in schizophrenia:

A. Duration of illness
B. Age of onset
C. Severity of positive symptoms
D. Number of positive symptoms

**Core Concept:** In schizophrenia, a good prognostic factor refers to an element that predicts a more favorable disease course and prognosis. These factors are generally associated with better treatment outcomes and a lower risk of relapse.

**Why the Correct Answer is Right:**

The correct answer is **B. Age of onset**. The age of onset of schizophrenia is considered a good prognostic factor because it has been found to have a significant impact on the disease course. Generally, a younger age of onset (typically before 20 years) is associated with a more severe and chronic course of the disease. This may lead to a worse response to treatment and higher risk of relapse.

**Why Each Wrong Option is Incorrect:**

A. **Duration of illness (A)** is not a good prognostic factor. In schizophrenia, the duration of illness may not have a consistent correlation with prognosis, as the course can vary widely even within the same duration.

C. **Severity of positive symptoms (C)** is not a good prognostic factor. Although severe positive symptoms may indicate a more severe disease, they do not necessarily predict a better prognosis, as the presence of negative symptoms, cognitive impairment, and overall functional impairment are more relevant for prognosis.

D. **Number of positive symptoms (D)** is not a good prognostic factor. The number of positive symptoms does not directly correlate with prognosis, as other factors, such as age of onset, duration of illness, and overall functioning, are more influential.

**Clinical Pearl:**

In schizophrenia, a careful evaluation of multiple factors is essential for predicting prognosis. These factors include age of onset, duration of illness, severity of negative symptoms, cognitive impairment, and overall functional impairment. The presence of fewer positive symptoms does not guarantee a better prognosis, as these factors have a more significant impact on the disease course and treatment outcomes.