Abstract
Apathy is a common neurobehavioral feature in a variety of neuropsychiatric disorders. Apathy is often interpreted as a sign of deppression or as a nonspecific symptom of other medical conditions. However, recent research indicates that the essential meaning of apathy is lack of motivation. This article presents a frame work for the classification and differential diagnosis of apathy and addresses issues related to the assessment and treatment of apathy in neuro phychiatric patients.

Introduction
To most clinicians, apathy is a vaguely defined symptom suggesting a lack of Interest or emotion. Patients who present with these and related symptoms (eg. lack of feeling or concern, indifference, flat affect and/or emotional unresponsiveness) are often described as being apathetic. In the clinical setting, apathy is commonly interpreted as a sign of depression or as a non-specific symptom of a variety of other medical disorders. The prevalence of apathy in different neuropsychiatric populations and research data indicating that apathy may occur in the absence of other depressive symptoms have led to the development of a framework for classification and differential diagnosis of apathyl. Additionally, criteria for diagnosing apathy as a clinical syndrome have been proposed 2,3.

Definition of Apathy
Defining apathy as a lack of emotion or interst leads to ambiguity because emotion and interests are related but clearly not the same. More recently, apathy has been defined as lack of motivationl-3. Lack of motivation is operationalized as the "simultaneous decrease in the overt behavioral, emotional, and cognitive concomitants of goal-directed behaviors"3. The central role of gole-directed behavior in the definition indentifies apathy with the domain of psychological functioning concerned with motivation. The diagnsis of apathy requires a diminution in observable goal- directed behavior relative to a person's age and culture. Apathy under the above definition also requires evidence of a descrease in emotional reactivity. For example, patients with apathy will show diminished emotinal distress in response to pleasant or unpleasant event. Finally, thought content must be considered. The diagnosis of apathy requires diminition of goal-realated cognitions such as diminished goals for the future, diminished interest.

Syndrome of Apathy
The application of the above definition of apathy to clinical practice requires guidelines for distinguishing apathy as a symptom and syndrome. According to the American Psychiatric Association 4, a syndrome is a recurring and discriminable pattern of symtoms that has heuristic value for diagnosing and treating patients. Once the presence of apathy has been determined, therefore, the next question is whether to regard as a symtptom of some other syndrome or as a syndrome itself.
    
                                                               Table 1: Criteria for the syndrome of Apathy

A. Lack of motivation relative to the patient's previous level of functioning or the standards of his/her age and culture, as evidenced by all three of the following: I. Diminished goal-directed behavior •   Lack of productivity •   Lack of effort •   Lack of time spent in activities of interest •   Lack of initiative or perseverance •   Compliance/dependency on others to structure activity •   Diminished socialization or recreation ll . Diminished goal-directed cognition •   Lack of interests, lack of interest in learning new things,lack of interest in      newexperiences •   Lack of concern about one's personal health or functional problems •   Diminished importance or value attributed to such goal- related domains as      socialization,    recreation, productivity , initiative, preseverance, curiosity. lll. Diminished emotional concomitants of goal-directed behavior •   Unchanging affect •   Lack of emotional responsitivity to positive and negative events •   Euphoric or flat affect •   Absence of excitement or emotional intensity B. Lack of motivation is the dominant feature of the clinical presentation. If the lack of motivation is not the dominant feature, then apathy is a symptom of some other syndrome such as dementia, delirium, or depression.

Definition of Apathy
As a general rule, apathy is considered to be a symptom if the apathy is mild relative to other symptom. In such cases, the patient is described syndromally in terms of the other syndrome and apathy is considered a symptom of that syndrome. Examples include syndromes of intellectual impairment (ego dementia) and syndromes of impaired level of consciousness (eg, delirium).
The esential feature of the syndrome of apathy is diminished goal-directed behavior due to a lack of motivation 1-3. The extent to which apathy dominates the clinical picture determins the presence of a syndrom of apathy. In other

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1. Prof. Dr. A. H Mohammad Firoz, MBBS, D PM, MAPA, MCPA, MBA, FCPS, MRCP, FRCP
    Professor of Psychiatry, Director, National Institute of Mental Health, Dhaka
2. Dr. AHM Mustafizur Rahman
    Asstt. Professor of Psychiatry, National Institute of Mental Health, Dhaka