MEASUREMENT OF "MENTAL CLOUDING" AND OTHER SUBJECTIVE EFFECTS OF MORPHINE

¹ The Anesthesia Laboratory of the Harvard Medical School at the Massachusetts General Hospital, Boston, Massachusetts

Sixty-one nonaddict, nonpatient, adult, male, college and graduate students were given subcutaneous injections of placebo and morphine phosphate (10 mg/70 kg body weight). Before medication and at specified times after medication, the subjects gave information concerning various aspects of their sensations and moods by responding to a 12-item questionnaire and a 78-item adjective check list and by volunteering 3 or more adjectives or phrases to describe their feelings best at that time. The four experimental conditions under which medications were given and the methods of obtaining and quantitatively evaluating the subjective responses have been discussed.

The major subjective responses to morphine in the "somatic" area were dizziness, nausea, itchiness, headache and warmness. The major responses in the "nonsomatic" area were mental clouding, physical inactivity and mental inactivity, as defined in the text. An increase in dejection was also found. However this effect was weak in comparison to the effects in the other areas just mentioned. So also were the effects in the other emotional areas (friendliness, unfriendliness, security and anxiety). Possible influences of the testing situation on subjective morphine effects were discussed.

Certain of the "somatic" and inactivity responses were present to a significant degree as late as 7 hours after medication. However the period of peak action was between 1 and 4 hours after medication for most responses.

Most of the unpleasant or undesirable subjective responses given by the 61 subjects were ones classified under the headings of mental clouding, physical inactivity, mental inactivity and "somatic" responses rather than under the headings of dejection, anxiety and unfriendliness.

Mental clouding and physical and mental inactivity are powerful morphine effects. They are, for the first time, expressed here in quantitative terms.

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