Schizophrenia | What's the Difference Between Added Perceptions and Removed Emotions?

In the context of schizophrenia, the term "positive" does not imply something beneficial. Instead, it refers to the addition of psychotic behaviors not seen in healthy individuals. These symptoms represent a distortion of normal functions and include experiences that are not based in reality. The most prominent positive symptoms are hallucinations and delusions. Hallucinations are sensory experiences that occur in the absence of any external stimulus; auditory hallucinations, such as hearing voices, are the most common. Delusions are firmly held false beliefs that are resistant to reason or contradictory evidence. Examples include persecutory delusions, where an individual believes they are being harmed or plotted against, or grandiose delusions, involving a belief of exceptional talent or fame. Other positive symptoms can include disorganized thinking, which becomes apparent through confused or illogical speech, and grossly disorganized or catatonic behavior, which involves unpredictable agitation or a marked decrease in reactivity to the environment.

Negative symptoms represent the absence or reduction of normal emotions and behaviors. Unlike the more dramatic positive symptoms, negative symptoms are often more subtle and can be mistaken for depression or laziness, yet they are a core component of schizophrenia and cause severe impairment in daily life. Key negative symptoms include "affective flattening" or "flat affect," which is a reduced expression of emotions via facial expression, eye contact, and tone of voice. Another is "avolition," a significant lack of motivation to engage in purposeful activities, making it difficult to perform daily tasks like work, school, or personal hygiene. "Anhedonia" is the diminished capacity to experience pleasure from positive stimuli, while "alogia" refers to a reduction in the quantity of speech. These symptoms collectively contribute to social withdrawal and a profound inability to sustain relationships and independent living.

Yes, current evidence indicates that positive and negative symptoms are associated with distinct dysfunctions in the brain's dopamine pathways. The "dopamine hypothesis" of schizophrenia posits that positive symptoms, such as hallucinations and delusions, are linked to an overactivity of dopamine in the mesolimbic pathway. In contrast, negative symptoms, along with cognitive deficits, are thought to be related to a deficit of dopamine activity, or hypoactivity, in the mesocortical pathway, which projects to the prefrontal cortex. This neurobiological distinction explains why a single treatment approach may not be equally effective for all symptoms of the disorder.

The differential response to treatment is rooted in the neurochemical differences between the symptom types. Traditional antipsychotic medications primarily function as dopamine D2 receptor antagonists, meaning they block dopamine activity. This mechanism is highly effective at mitigating the dopamine hyperactivity in the mesolimbic pathway, thereby controlling positive symptoms. However, these medications do not effectively address, and can sometimes worsen, the dopamine hypoactivity in the mesocortical pathway responsible for negative symptoms. Consequently, negative symptoms persist as a major therapeutic challenge, often causing more long-term disability and poor functional outcomes than the more overt positive symptoms.

Cognitive symptoms are a core and enduring feature of schizophrenia that significantly impact an individual's ability to function. These deficits in thought processes are distinct from positive and negative symptoms and are a primary predictor of long-term functional outcome. Key cognitive impairments include poor "executive functioning," which is the ability to understand information, process it, and use it to make decisions and plan for the future. Individuals also experience deficits in "working memory," the capacity to hold and manipulate information for short periods, which is essential for reasoning and learning. Furthermore, problems with "attention" make it difficult to focus on tasks and filter out irrelevant information. These cognitive deficits are not as dramatic as psychosis but are pervasive, consistently interfering with a person's ability to manage finances, maintain employment, and live independently.