HealthDay News) -- Occasionally forget an appointment or a friend's name? Then you may have a loss of brain volume, a new study suggests.

Researchers scanned the brains of almost 500 people reporting such momentary forgetfulness and found that the size of their hippocampus -- an area of the brain important for memory and one of the first areas damaged by Alzheimer's disease -- was a few fractions of a millimeter smaller than people without such lapses.

The study was expected to be published in the Oct. 7 issue of Neurology.

WASHINGTON (Reuters) - Long-term heavy use of marijuana may cause two important brain structures to shrink, Australian researchers said on Monday.

Brain scans showed the hippocampus and amygdala were smaller in men who were heavy marijuana users compared to nonusers, the researchers said. The men had smoked at least five marijuana cigarettes daily for on average 20 years.

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