**Core Concept**
Disorders of form of thought refer to abnormalities in the organization and structure of thought processes, which can manifest as disorganized thinking, loose associations, or a lack of logical coherence. This concept is crucial in psychiatry and psychology for diagnosing and managing various mental health conditions.

**Why the Correct Answer is Right**
The correct answer is a disorder that does not primarily affect the form or organization of thought. To determine this, we need to consider the characteristics of each option. Disorders of form of thought are often associated with schizophrenia, schizoaffective disorder, and other psychotic conditions.

**Why Each Wrong Option is Incorrect**
**Option A:** Schizophrenia is a classic example of a disorder that affects the form of thought, characterized by disorganized thinking, loose associations, and a lack of logical coherence.
**Option B:** Schizoaffective disorder also involves disorganized thinking and a break from reality, making it another disorder of form of thought.
**Option C:** Catatonia is a disorder that affects the content of thought, but it can also involve disorganized thinking and a break from reality, making it a disorder of form of thought as well.

**Clinical Pearl / High-Yield Fact**
Disorders of form of thought are often associated with a break from reality, which can manifest as delusions or hallucinations. This is a key distinguishing feature from other psychiatric conditions.

**Correct Answer: D. Depression.**