Understanding subjective memory complaints in ageing : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University, Wellington, New Zealand
Everyday memory difficulties are a common experience with age, and cause
considerable distress for many people when they are interpreted as potential indicators
of age-related disease. However, research literature examining the relationship between
these difficulties (known as subjective memory complaints; SMCs) and actual memory
performance on neuropsychological tests has shown mixed results, suggesting that
SMCs are not a pure reflection of memory ability, but instead that their aetiology is
complicated and not fully understood. Both psychological and methodological factors
are also implicated, although no research has yet comprehensively examined how a
combination of these factors might predict SMCs.
The current research aimed to test a new aetiological model of SMCs that incorporated
a range of potential confounds. It was hypothesised that SMCs would be predicted by
measures of processing speed and executive functioning, and that this relationship
would be moderated by measures of anxiety and depression.
First, a meta-analysis and systematic review of existing research on the relationship
between subjective and objective memory was conducted as a platform to inform
subsequent analyses. Then, Study A addressed current variation in assessment methods
by describing differences in SMCs when assessed with both an open-ended measure and
a prescriptive questionnaire. Study B examined how these differences in subjective
reports related to objective memory performance. Finally, Study C tested the proposed
aetiological model of SMCs.
Study A showed that different measures of SMCs garnered non-overlapping reports.
SMCs gathered via the open-ended measure were fewer in number, but rated as more
distressing, than those endorsed on the questionnaire. Spontaneous reports appeared to
be more ecologically valid reflections of SMCs, although questionnaire assessments
were by their nature more robust to a “catch 22” situation whereby some endorsed
SMCs were not reported spontaneously (perhaps due to memory failures in themselves).
Study B found that neither method of assessing SMCs produced reports that were
significantly convergent with objective measures of memory functioning. Study C
found partial support for the hypothesised aetiological model. SMCs (as assessed by the
questionnaire) were inversely related to processing speed, but only when depressive
symptoms were relatively high. Collectively, results offer important insights into the
interaction of cognitive and psychological factors in explaining SMCs, and highlight the
previously undelineated context in which processing speed contributes to SMCs.