CANNABIS USE AND COGNITIVE DECLINE IN PERSONS UNDER 65 YEARS OF AGE

The purpose of this study was to investigate possible adverse effects
of cannabis use on cognitive decline after 12 years in persons under
age 65 years.

This was a follow-up study of a probability sample of the adult
household residents of East Baltimore. The analyses included 1,318
participants in the Baltimore, Maryland, portion of the Epidemiologic
Catchment Area study who completed the Mini-Mental State (MMSE)
examination during three study waves in 1981, 1982, and 1993--1996.
Individual MMSE score differences between waves 2 and 3 were
calculated for each study participant. After 12 years, study
participants' scores declined a mean of 1.20 points on the MMSE
(standard deviation 1.90), with 66% having scores that declined by at
least one point.

Significant numbers of scores declined by three points or more (15% of
participants in the 18--29 age group). There were no significant
differences in cognitive decline between heavy users, light users, and
nonusers of cannabis.

There were also no male-female differences in cognitive decline in
relation to cannabis use. The authors conclude that over long time
periods, in persons under age 65 years, cognitive decline occurs in
all age groups. This decline is closely associated with aging and
educational level but does not appear to be associated with cannabis
use.