Mikhail Gorbachev major campaign to limit alcohol consumption, which Gorbachev—who believed it would improve health and work efficiency—oversaw. His wife keenly supported the measure. As a result, crime rates fell and life expectancy grew slightly between 1986 and 1987. The reform had significant costs to the Soviet economy, resulting in losses of up to $100 billion between 1985 and 1990. Gorbachev later considered the campaign to have been an error. In April 1986 the Chernobyl disaster occurred; in the immediate aftermath, officials fed Gorbachev incorrect information to downplay the incident. As the scale of the disaster became apparent, 336,000 people were evacuated
Mikhail Gorbachev attaining a PhD in sociology in 1967 from the Moscow Pedagogical Institute; while in Stavropol she too joined the Communist Party. Stalin was ultimately succeeded as Soviet leader by Nikita Khrushchev, who denounced Stalin and his cult of personality in a speech given in February 1956, after which he launched a de-Stalinization process throughout Soviet society. Later biographer William Taubman suggested that Gorbachev "embodied" the "reformist spirit" of the Khrushchev era. Gorbachev was among those who saw themselves as "genuine Marxists" or "genuine Leninists" in contrast to what they regarded as the perversions of Stalin. He helped spread Khrushchev's anti-Stalinist