Reduced affect display, sometimes referred to as emotional blunting or emotional numbing, is a condition of reduced emotional reactivity in an individual. It manifests as low emotional expressivity, whether verbally or nonverbally, especially when talking about issues that would normally be expected to engage emotions. In this condition, expressive gestures are rare and there is little animation in facial expression or vocal inflection. Additionally, reduced affect can be symptomatic of autism, schizophrenia, depression, post-traumatic stress disorder, depersonalization-derealization disorder, and schizoid personality disorder. It may also be a side effect of certain medications (e.g., antipsychotics and antidepressants). However, reduced affect should be distinguished from apathy and anhedonia, which explicitly refer to a lack of emotional sensation. The ICD-11 identifies several types of affect disturbances, particularly focusing on variations in the reduction of emotional expression. Constricted affect refers to a noticeable limitation in the range and intensity of expressed emotions, though it is less pronounced than blunted affect. Blunted affect, in turn, describes a more severe reduction in emotional expressiveness, though not as extreme as flat affect, which is characterised by an almost complete absence of any observable emotional expression.
Types
Constricted affect A restricted or constricted affect is a reduction in an individual's expressive range and the intensity of emotional responses.
Blunted and flat affect Blunted affect is a lack of affect more severe than restricted or constricted affect, but less severe than flat or flattened affect. "The difference between flat and blunted affect is in degree. A person with flat affect has no or nearly no emotional expression. They may not react at all to circumstances that usually evoke strong emotions in others. A person with blunted affect, on the other hand, has a significantly reduced intensity in emotional expression".
Shallow affect Shallow affect has an equivalent meaning to blunted affect. In the Psychopathy Checklist, Factor 1 identifies shallow affect as a common attribute of psychopathy.
Brain structures Individuals with schizophrenia with blunted affect show different regional brain activity in fMRI scans when presented with emotional stimuli when compared to individuals with schizophrenia without blunted affect. For instance, individuals with schizophrenia without blunted affect show activation in the following brain areas when shown emotionally negative pictures: midbrain, pons, anterior cingulate cortex, insula, ventrolateral orbitofrontal cortex, anterior temporal pole, amygdala, medial prefrontal cortex and extrastriate visual cortex. Individuals with schizophrenia exhibiting blunted affect instead only show activation in the midbrain, pons, anterior temporal pole and extrastriate visual cortex.
Limbic structures Individuals with schizophrenia exhibiting flat affect show decreased activation in the limbic system when viewing emotional stimuli. In these individuals, neural processes begin in the occipitotemporal region of the brain, routing through the ventral visual pathway and the limbic structures until they reach the inferior frontal areas. Damage to the amygdala of adult rhesus macaques early in life can permanently alter affective processing. Lesioning the amygdala causes blunted affect responses to both positive and negative stimuli. This effect is irreversible in the rhesus macaques; neonatal damage produces the same effect as damage that occurs later in life. The macaques' brain cannot compensate for early amygdala damage, even though significant neuronal growth may occur. There is some evidence that blunted affect in schizophrenia patients is not only caused by low amygdala response, but also lack of integration with other areas of the brain associated with emotional processing, particularly in amygdala-prefrontal cortex coupling. Damage in the limbic region prevents the amygdala from correctly interpreting emotional stimuli in individuals with schizophrenia by compromising the link between the amygdala and other brain regions associated with emotion.
Brainstem Parts of the brainstem are responsible for passive emotional coping strategies characterized by disengagement or withdrawal from the external environment (quiescence, immobility, hyporeactivity), similar to what is seen in blunted affect. Individuals with schizophrenia with blunted affect show activation of the brainstem during fMRI scans, particularly the right medulla and the left pons, when shown "sad" film excerpts. The bilateral midbrain is also activated in individuals with schizophrenia diagnosed with blunted affect. Activation of the midbrain is thought to be related to autonomic responses associated with the perceptual processing of emotional stimuli. In individuals with schizophrenia, impaired connection of the midbrain and prefrontal cortex is associated with reduced emotional affect.
Prefrontal cortex The prefrontal cortex, similarly to the limbic system, plays a role in the induction of an emotion and the regulation of emotions in healthy individuals. Individuals with schizophrenia show no changes in activation of the prefrontal cortex (PFC) when observing external sad stimuli, whereas healthy controls and patients with schizophrenia who were treated with quetiapine for blunted affect show activation of the medial PFC on fMRI. Individuals with schizophrenia who were reconditioned with quetiapine showed activation in other areas of the PFC as well, including the right medial prefrontal gyrus and the right and left orbitofrontal gyrus. This lack of PFC activity in people with schizophrenia with blunted affect has been postulated to be related to the impaired emotional processing observed in such individuals.
Anterior cingulate cortex A positive correlation has been found between activation of the anterior cingulate cortex and the reported magnitude of sad feelings evoked by viewing sad film excerpts. The rostral subdivision of this region is possibly involved in detecting emotional signals. This region is different in individuals with schizophrenia with blunted affect.
Diagnoses
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