Table 1.

Differential diagnosis of negative symptoms.

Negative symptoms	Depression	Parkinsonism
Emotional blunting	Anhedonia, indifference, anesthesia	Indifference, amimia
Apatho-abulic disorders (reduced psychic energy potential)	Motor retardation	Akinesia, increased muscle tone
Cognitive impairment, poverty of speech and associative thinking	Mental retardation, difficulties with concentration	Bradypsychia, cognitive impairment, decreased vigilance, difficulties with concentration, impaired speech production
Autism	Social withdrawal	Forced restriction of social contacts