Negative symptoms are thoughts, feelings, or behaviors normally present that are absent or diminished in a person with a mental disorder.
Examples of negative symptoms are social withdrawal, apathy (decreased motivation), poverty of speech (brief replies), inability to experience pleasure (anhedonia), limited emotional expression, or defects in attention control. The term "negative symptoms" is specifically used for describing schizophrenia , but sometimes used more generally in reference to disorders such as depression or dementia . These symptoms may be associated with altered brainwave activity or brain damage. They can be more difficult to diagnose than positive symptoms ( hallucinations , delusions , bizarre behavior, or formal thought disorder) because they represent a lesser degree of normal, desirable activity rather than the presence of undesirable or bizarre behavior. Side effects of certain medications, demoralization (loss of positive emotions like hope or confidence usually as the result of situations in which one feels powerless), or a lack of stimulation in one's environment can also cause negative symptoms, so these possibilities must be ruled out before attributing the symptoms to a disorder.
Sandra L. Friedrich, M.A.