Definition
Noogenic neurosis (Gr. nous - spirit) is a neurosis whose source is not a psychological conflict in the traditional sense but a spiritual problem: a crisis of meaning, a conflict of conscience, a clash of values.
Frequency
Frankl and his co-workers estimated that about 20% of neuroses are noogenic. Psychometric research (including Crumbaugh and Maholick, 1964, the PIL test) showed that a low sense of meaning is a phenomenon distinct from classical neurotic symptoms.
Therapy
Noogenic neurosis calls above all for specific logotherapy - work on meaning and values, not only on symptoms. Frankl distinguished it from psychogenic and somatogenic neuroses.
Today
The current ICD-11 classification covers phenomena close to this concept under the heading of so-called demoralisation (loss of hope and meaning).
Sources
Wikipedia: Noogenic neurosis; Logotherapy; J. Crumbaugh, L. Maholick, An experimental study in existentialism (1964).