Isn't faking a mental illness, kinda a mental illness in itself?
The underlying reason for faking it could be to get some sort of advantage. This extreme approach could be due to sociopathic/psychopathic/apathic behavior. Or an irrational need for attention.
Malingering can take many forms. However, as specifically related to mental illness, the tendency is to fake more common disorders such as major depressive disorder , post-traumatic stress disorder , and panic disorder with agoraphobia . With very little coaching or research, even a beginner can simulate symptoms of these disorders. Generalized symptoms such as headaches, dizziness, low back pain, stomach pain, etc., are easily manufactured, and x rays, magnetic resonance imaging (MRIs), or CAT scans (computed axial tomography) are unable to determine a physical cause.
Malingerers tend to avoid symptoms such as those associated with more serious psychiatric disorders, because the pretense is very difficult to maintain and objective measures could detect the difference. For example, hearing voices and seeing demons, or living with the idea that others can hear unspoken thoughts, would become a difficult act to maintain over time. On the other hand, to feign a sad mood, loss of interest in formerly enjoyed activities, or a low energy level may not be so difficult to demonstrate. Likewise, responding positively to a series of questions about having heart palpitations, sweating, dizziness, or fear of impending death, could be done readily.
The concept that fakers use less severe symptoms to escape detection was validated in 2001 in a research study. Individuals were asked to fake mental illnesses in such a way as to avoid detection by sophisticated psychological tests. All or portions of the following tests were employed in the research: the Structured Inventory of Malingered Symptomatology, the Psychopathic Personality Inventory, the M-Test, and the Trauma Symptom Inventory. Slightly over 11% of the 540 research participants successfully avoided detection and were diagnosed with real disorders instead of with malingering. Questionnaires completed by those who successfully faked symptoms showed that they avoided detection by endorsing fewer actual symptoms, staying away from unduly strange or bizarre symptoms, and responding based upon personal experience.