How long have you got? The majority of post-classical works dwell on anxiety at some point, such is the Romantic flavour. Let's see...
- Mahler Symphonies 1,2,3,5,6,7 and 9, along with the Kindertolenlieder
- Near enough every note of Rachmaninov, save perhaps certain movement of the symphonies and piano concerti. Particularly anxious are the opening of the Second, Isle of the Dead, The Bells, most of the piano preludes (especially Op5 C# Minor; Op.32 nos 2 and 10)
- Tchaikovsky 4,5,6, Manfred, Swan Lake, Eugene Onegin,
- Bartok Duke Bluebeard's Castle; Miraculous Manderin; Music for Strings, Percussion and Celeste; Concerto for Orchestra mvts 1 and 3; String quartets
- Every Shostakovich symphony from 4 onwards, and no.1; string quartets (especially 8), violin concerto no.1,
- Leonard Bernstein On the Waterfront score, and much of West Side Story and his symphonies (one is called 'The Age of Anxiety')
- Britten Peter Grimes, Turn of the Screw, War Requiem, Nocturne, Sinfonia da Requiem.
- Sibelius Tapiola, Symphony 1,5 mvt. 1 and Kullervo
As for a frenzy:
- Beethoven Grosse Fugue
- Shostakovich 10 mvt. 2
- Mahler 9 mvt. 3
- Sibelius The Tempest music
- Final sections of The Rite of Spring