Gemini AI, when asked to play the role of an experienced psychiatrist, pretty much concurs with the above. Here goes:

Prompt: "For a change, play the role of an experienced psychiatrist. Tell me the difference between depression and negative symptoms in a schizoaffective disorder.

Gemini's generation:

It's an important question, and the distinction between depressive symptoms and negative symptoms in schizoaffective disorder is indeed one that can be subtle and challenging, even for experienced clinicians. They often look similar on the surface, but their underlying mechanisms and implications for treatment can differ.

Let's break down the differences from a psychiatric perspective:

Depression (as a Mood Episode)
When we talk about a major depressive episode in the context of schizoaffective disorder, we're referring to the mood symptoms that are also seen in Major Depressive Disorder (MDD). These symptoms reflect a disturbance in affect and cognition.

Key features of a depressive episode (DSM-5 criteria):

Depressed mood: Feeling sad, empty, hopeless, or irritable for most of the day, nearly every day.

Anhedonia: Markedly diminished interest or pleasure in all, or almost all, activities. This is a core symptom.

Weight/Appetite changes: Significant weight loss or gain, or decrease/increase in appetite.

Sleep disturbances: Insomnia (difficulty sleeping) or hypersomnia (sleeping too much).

Psychomotor agitation or retardation: Observable restlessness or slowed movements/speech.

Fatigue/Loss of energy: Feeling tired nearly every day.

Feelings of worthlessness or excessive/inappropriate guilt: Often pervasive and not easily dismissed.

Diminished ability to think or concentrate: Difficulty focusing, indecisiveness.

Recurrent thoughts of death or suicide: Ranging from ideation to plans or attempts.

Crucially, with depression, these symptoms are often accompanied by subjective distress. The person usually feels bad, knows they are depressed, and often seeks help or expresses a desire for things to change. There's often a sense of sadness, despair, or profound emotional pain.

Negative Symptoms (of Schizoaffective Disorder/Schizophrenia Spectrum)
Negative symptoms represent a diminution or absence of normal mental functions or behaviors that should be present. They are considered core features of psychotic disorders and can be particularly debilitating.

Key features of negative symptoms:

Diminished emotional expression (formerly "flat affect"): Reduced intensity in the expression of emotions through facial expressions, eye contact, intonation of speech (monotone voice), and gestures. The person might feel emotions but not show them outwardly.

Avolition: A decrease in motivated, self-initiated purposeful activities. This is more than just feeling tired or unmotivated (as in depression); it's a profound lack of drive to engage in even basic daily tasks (e.g., hygiene, work, school).

Alogia (poverty of speech): A decrease in the amount or fluency of speech. The person might give brief, empty replies, or appear to have difficulty thinking of what to say.

Anhedonia: (This one is tricky, as it overlaps with depression.) A diminished ability to experience pleasure from positive stimuli. However, in negative symptoms, it might be a more pervasive, baseline inability to anticipate or experience pleasure, rather than primarily a loss of interest due to low mood.

Asociality: Apparent lack of interest in social interactions, leading to social withdrawal. This is often due to a lack of motivation to seek social contact, rather than social anxiety or sadness (though those can also be present).

Crucially, people experiencing prominent negative symptoms often have less insight or subjective distress about these symptoms compared to depressive symptoms. They might not realize their affect is flat, or that they lack motivation. Family members often notice these symptoms more than the individual themselves. They can often appear apathetic or indifferent, even if they're not necessarily sad."