IT IS NOT TRUE that people began to write music about drugs only in the '60s. The oldest (and still the best) piece of music about a bad trip was composed in 1830 and is featured in this week's National Symphony concerts.

In the "Symphonie Fantastique" of Hector Berlioz, a young musician, victim of a blighted romance, takes opium in a suicide attempt. Instead of dying, he falls into a long sleep, full of strange, obsessive visions. The woman of his fantasies is represented by a melody that recurs throughout, with changing symbolic and emotional overtones.

In his fantasy, he murders her and is marched to the guillotine. As the blade ends his life, the thematic melody running through his mind is chopped off half-finished. Then a grotesque dance of witches, ghosts and monsters is held to celebrate his death. In the melody's final transformation, the loved one "joins the infernal orgy." There is a strange passage where the violins and violas are played with the wooden side of the bow rather than the horsehair, producing a sound that might be skeletons dancing.

In the last two movements, Berlioz goes far beyond anything ever done before in music, and the art of modern orchestration is born.

A score of versions of the "Symphonie Fantastique" have already been issued on compact disc. The vivid reading by Charles Dutoit with the Orchestre Symphonique de Montreal gives great satisfaction, but the old Charles Munch recording (remastered for CD with a superb performance of the Berlioz Requiem) also deserves consideration. SYMPHONIE FANTASTIQUE --

Conducted by Dutoit (London 414 203-2); conducted by Munch (RCA 6201-2-RC; two CDs).

To be performed by the NSO at 1:30 Friday, 8:30 Saturday and 7 Tuesday at the Kennedy Center Concert Hall.