Dear Carsten Spohr,
No medical or psychological tests can ever disclose a typical unipolar depression unless the tests are performed during the periods of illness.
This is why medical and psychological testing MUST always be combined with a thorough medical history questioning also family members and/or others persons that know the person in question well. If scrutinizing a persons medical history means an unipolär illness or anything close to it is discovered the person is not suitable for a pilots work. Especially as unipolar illnesses have a tendency to become more severe over the years.
Being a specialist on malingering, i.e. illness deception, I like to add a comment that some patients actually simulate being healthy although they are severely ill.
We are all deeply concerned re. this unbelievable tragedy.
Dr. Thomas Jackson, psychiatrist