The self report of everyday memory deterioration in neurologically impaired subjects : reliability and validity

The present study investigated the reliability and validity of neurologically impaired patients' ability to report on the deterioration in their everyday memory. In order to do so, a thirty-five item questionnaire, the Metamemory Change Questionnaire (M.M. C. Q.), was constructed and subjects' responses were validated against their performance on the Wechsler Memory Scale (W .M. S.), an objective index of memory deterioration, and a close relative's ratings concerning the patient's memory problems. Forty one outpatients with confirmed neurological conditions were selected according to a set of inclusion criteria. Each subject endorsed the M.M.C.Q. twice in order to determine the questionnaire reliability, and they were also required to indicate their overall perception of change on a single five point Likert scale. On the second occasion, he/she was also administered the W.N.S. and the National Adult Reading Test. An index of deterioration was then calculated by comparing his current memory quotient to his estimated premorbid verbal I.Q.. At that stage a relative was also requested to independently endorse the N.M.C.Q. according to that person's perception of the patient. The data obtained from these various measures were then subjected to correlation analyses. The M.M.C.Q. was found to be a very reliable instrument, and good agreement was obtained between the patients' and relatives' estimates of the subjects' memory deterioration. Its relationship to the I.Q. minus M.Q. index of deterioration was, however, dependent on the severity of the respondent's memory impairment. Thus the magnitude of correlations between subjective reports and test performance was substantially greater in the more severely affected subjects. A similar pattern of results was obtained with the simple overall rating scale, so that the relative merits of using the entire M. M. C. Q. over that global judgement will require further investigation. The results of this study are interpreted as suggesting that more severe memory impairment is associated with more accurate self report of deterioration. Alternative explanations are discussed and suggestions for further research offered.