Portrait of a Depressed Danish Journalist Living in Paris : SNAKE IN THE HEART by Henrik Stangerup translated from the Danish by Anne Born; Marion Boyars $24.95, 315 pages

Even paranoid people have enemies, the saying goes, with the implied corollary: enemies they probably wouldn’t have if they weren’t paranoid in the first place.

Depressives are no better off, if we are to believe this sometimes satirical, sometimes gloomy novel about a Danish journalist in Paris, first published in 1969. Its antihero, Max Mollerup, is chronically insecure, and every quick fix he finds for his wobbly ego only sabotages him in the long run.

Henrik Stangerup, a journalist himself as well as one of Denmark’s leading fiction writers, uses a quotation from the young Karl Marx as his epigraph: “Self-disgust is a snake that constantly pierces and gnaws at the breast, sucks the lifeblood out of the heart and blends it with the poison of despair and the hatred of humanity.”

How serious is he, we wonder. Such portentous words seem to mock Mollerup’s downfall, which has such trivial, even comical, causes as his flubbing a question at one of Charles de Gaulle’s press conferences in 1964 and being caught by his mother in the bedroom of his live-in Spanish maid. Yet the downfall is real and convincing.

The answer seems to be that Stangerup, who dealt with the age of Kierkegaard in “The Seducer,” the Spanish colonization of Mexico in “Brother Jacob” and the ordeals of a 19th century Danish scientist in Brazil in “The Road to Lagoa Santa,” is a serious writer indeed, but one who is working here in a lighter style--for him.

Mollerup has plenty of reasons to be depressed. His once-bright promise as a reporter has been tarnished by what, in his more honest moments, he admits is his own growing sloppiness. A rival correspondent is scooping him, and a youngster at his own newspaper is gunning for Mollerup’s job. He is a disappointment to his mother, who was a silent film star of the 1920s and is still a renowned figure in the European cinema world.

A bachelor in his 40s, Mollerup prefers the company of prostitutes to more involving relationships. Early in “Snake in the Heart,” he meets an attractive Italian woman, Claudia Benedetti, but their affair founders--either because he is afraid to show he cares for her or because she cares too little for him; he can’t figure it out, exactly, and neither can we.

This is typical of Stangerup’s approach. He isn’t interested in explaining Mollerup’s neurosis. He just shows how it works.

Mollerup’s escalating blunders--some verging on slapstick--are described in voluminous detail, as are Paris and Copenhagen and the artistic and political controversies of the day.

Some of this can’t help but make for heavy reading, despite Anne Born’s lucid translation. Elsewhere, though, it’s a key to the novel’s humor. Stangerup is poking fun at the inferiority complex felt by Danes like Mollerup--whose language “was understood by a nation of only 4 [million] or 5 million people”--in a big country like France, which in turn was being “Americanized” by an even bigger one.

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The surprising thing about “Snake in the Heart,” in fact, is how little it has dated.

This isn’t just because artistic and political controversies all have a family resemblance. It’s because Stangerup has such a firm grasp of the insecure mind. Failing to adapt to the world as it is, the depressive begins to cut down the world to fit him, lopping off human contacts here, shrinking expectations there, until he is left with--as Dostoevsky wrote in “Notes From Underground”--a mere mouse hole.

“Do you know how your thoughts can be more real than . . . reality?” a mad American tourist asks Mollerup in Venice, where his last-ditch effort to win Claudia has landed him a bit part in a movie--while, back in Paris, the book he wrote in a last-ditch effort to revive his career is about to be exposed in a plagiarism scandal. “Then you know everything in the world is made up purely of mental processes.”