O4‐06‐02: Mental health versus physical health as determinants of cognition in midlife

Abstract

We now know that Alzheimer's pathology develops over many years prior to the emergence of the clinical syndrome. To minimise later risk for dementia, there is increasing emphasis on managing both mental health, including depression, and physical health including cardiovascular and metabolic function, throughout life. The CANTAB paired associates learning (PAL) test is a non-verbal assessment of episodic memory which is, in older adults, highly sensitive to the early signs of Alzheimer's disease. We investigated the extent to which performance on this test in the general population during middle adulthood is associated with physical and mental health. At the age of 46 years, 5607 members of the 1966 Northern Finland Birth Cohort completed the CANTAB PAL. This unique longitudinal study has followed from birth 96% of all children born in Northern Finland whose expected day of birth was in the year 1966. Mental health was assessed at ages 31 and 46 using the Hopkins Symptom Check List questionnaire, a 25-item measure including depression and anxiety subscales. Indicators of physical health were reported at age 46 including current smoking status, body mass index, measures of physical activity, and measures of inactivity (time spent sitting). Demographics (sex and education level) together explained 4% of variance in memory scores in midlife. Controlling for these, neither current levels of depression or anxiety, nor depression or anxiety measured 15 years prior were significantly associated with memory performance. Indicators of physical health were significantly associated with memory performance, together explaining a further 3% of variance in cognitive scores. Midlife memory performance is highly influenced by physical health but - in this general population birth cohort - unaffected by common symptoms of anxiety and depression. This large study provides strong evidence for the importance of lifestyle in determining brain health, even in middle age. Primary and secondary prevention strategies for dementia may need to take into account lifestyle throughout adulthood in determining who is at highest risk and which interventions will be most effective.