Avolition is defined as a reduction in the motivation to initiate or persist in goal-directed behaviour. It forms part of the cluster of symptoms known as the negative syndrome of schizophrenia. ‘Negative’ refers to the deficit of symptoms. (Compare positive symptoms which refer to the ‘surplus’ of symptoms).
The other symptoms which form part of the negative cluster of symptoms include asociality, avolition and anhedonia (a reduction in the ability to experience pleasure). Flat affect or diminished expression of emotion and alogia (diminished speaking) – manifest as impoverished thinking - are often included in this group.
Negative symptoms are important because unlike the positive symptoms, they can sometimes be difficult to recognise. Positive symptoms are also ‘easier’ to treat compared to negative symptoms which contribute significantly to the functional decline of schizophrenia patients.
Avolition and other negative symptoms are a major public health concern.
These negative symptoms are sometimes distinguished into 2 groups, viz primary negative symptoms and secondary symptoms. Secondary negative symptoms may be attributable to factors such as persisting positive symptoms, the adverse effects of medications or to the social isolation which schizophrenia patients sometimes experience. Primary negative symptoms are directly attributable to the schizophrenia disease itself and are associated with poorer clinical and functional outcomes.
There are numerous complicated theories about the underlying dysfunction which is beyond the scope of this article. Different classes of neurotransmitters and various neural circuits in the brain have been suggested to be implicated in the pathogenesis of avolition and the negative syndrome. These have included dopamine, serotonin, opioids, noradrenaline, the orbito-frontal circuit, ventral and dorsal parts of the striatum, midbrain, dorsal anterior cingulate cortex and the dorsolateral prefrontal circuit.
Negative symptoms are, simplistically, seen to arise when individuals are unable to develop an internal representation of external events, experiences, rewards and goals. There are therefore no desired future goals and this leads to the decline of functional capacity. It is not to say that these individuals do not enjoy these experiences, they do not have the motivational drive to put themselves in the position to obtain it.
Currently there is a lack of reliable and effective treatment for avolition and other primary negative symptoms, but despite this, accurate diagnosis is still required to identify secondary negative symptoms which may be caused by a comorbid mood, cognitive or physical disorder, and which may be treatable.
Some reports have suggested that antidepressant medication might be effective in managing the negative syndrome.
The second generation antipsychotics (SGAs) were marketed as being effective for relieving negative symptoms. This was based on the observation that it increased levels of dopamine in the frontal regions of the brain. Initial experiments were never successfully replicated in the real world with various patient populations and setting and differing comorbidities.
Scales to measure Negative Symptoms
The SANS, PANSS, BNSS and SDS are commonly used to measure negative symptoms.
The BNSS (Brief Negative Symptom Scale) is a 13-item instrument designed for clinical trials and other studies.
The PANSS (Positive and Negative Syndrome Scale). The negative symptom scale from the PANSS3 includes 7 items tapping blunted affect, emotional withdrawal, poor rapport, passive/apathetic social withdrawal, difficulty in abstract thinking, lack of spontaneity and flow of conversation, and stereotyped thinking.
The SANS (Scale for assessment of negative symptoms) currently consists of 19 items (prior versions included an additional item of inappropriate affect2 that was subsequently dropped39), representing 5 rationally derived scales: Affective Flattening or Blunting, Alogia, Avolition-Apathy, Anhedonia-Asociality, and Inattention.
The SDS (Schedule for the deficit syndrome) consists of 6 negative symptoms involving restricted affect, diminished emotional range, poverty of speech, curbing of interests, diminished sense of purpose, and diminished social drive