The effects of berry juice on cognitive decline in older adults : a thesis presented in partial fulfilment of the requirements of Master of Arts in Psychology at Massey University, Palmerston North, New Zealand

This study examined the effects of blackcurrant and boysenberry juices on cognitive processes in older adults. Current research suggests that fruits such as these may be able to reverse some of the effects of ageing on cognition. The free radical theory of ageing proposes that individuals age because oxidative damage accumulates in cells and interferes with cell functions. The hardest working tissues such as the brain accumulate the most oxidative damage through respiration. Antioxidants can protect against free radical formation and damage. Anthocyanins can contribute to half of the antioxidant capacity of deeply coloured berry fruit. An increase in dietary antioxidants such as anthocyanins may help to alleviate free radical damage within the brain. Research has shown that oxidative damage within the brain can impair cognitive functioning. Working memory shows age-related decline, along with visuospatial abilities, word retrieval and sustained attention. Some of this decline is thought to be related to oxidative damage of neurotransmitters such as acetylcholine and areas of the brain such as the hippocampus. Past research with humans has shown that some antioxidants can affect cognitive functioning in an older population. Animal studies have also established that diets enriched with anthocyanins can improve memory, motor control and neurotransmitter functioning. The present study involved giving berry juice drinks to 52 older adults that had been assessed as having a mild impairment of cognitive function. The participants were divided into three groups and drank 200mL a day of either blackcurrant juice, boysenberry juice or a placebo for twelve weeks. The participants were assessed at three different times over the course of the experiment using the RBANS. The RBANS is sensitive to small changes in its tests of memory, visuospatial ability, language and attention. The results of this study did not support previous research on antioxidants and cognitive functioning. There were no significant interactions between berry juices and any of the cognitive domains assessed by the RBANS over the course of the experiment. Some of the limitations of the study may be responsible for a lack of effect. The experiment was short with a low dose of antioxidants, and there was little control over the participants altering their own diet after being informed of the reasoning behind the study

The effects of late-life depression on memory : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Clinical Psychology at Massey University, Manawatu, New Zealand

Depression is a common mental health issue. It can result in a number of difficulties with cognitive functions such as memory. This is particularly pertinent for those experiencing late-life depression (those aged 65 years and older), as it can lead to a reduced quality of life. The relationship between depression, short-term memory, working memory, and prospective memory in the literature was explored, with a special emphasis on memory and late-life depression. In general, past research is somewhat mixed although tends towards depression having a negative impact on all the above types of memory. The impact of depression on short-term, working, and prospective memories was investigated in a group of younger adults aged 20-29 years (n = 50) and older adults aged 70-79 years (n = 50). A between groups design was used, with each participant completing measures of depression, short-term memory (recall list), working memory (letter-number sequencing and reading span tasks), and prospective memory (with both time-based and event-based tasks). As moderating factors of memory, processing speed and an estimate of IQ were measured. Anxiety and perceived stress were measured as moderating factors for depression. The results of the present study were mixed. There were small effects for Depression and Depression x Age interactions across some of the working memory and time-based prospective memory analyses. Interesting results were obtained when the moderators were investigated. Visual processing speed and IQ had some small to medium effects for Depression and Depression x Age interactions for recall, reading span, and time-based prospective memory, although these effects were not always in the anticipated direction. Similar variable patterns appeared when the impact of anxiety and stress on memory were analysed. The implications of these mixed results are that a review of the way the constructs of depression, anxiety and stress are defined and measured is necessary for ongoing research in this area. Tests of depression are variable and have correlations with each other that are only marginally higher than their correlations with anxiety and stress measures. Difficulties with construct measurement extend to tests of working memory, with low correlations between working memory tests. This indicates that these tests may not be measuring the same things, yet current research on depression and memory often compares findings across multiple depression scales and tests of memory. This may have led to the inconsistent findings in the literature and may continue to do so until the issues of construct definition and measurement are addressed