Acquisition and short-term retention of inhaler techniques require intact executive function in elderly subjects

Background: patients with dementia are almost invariably unable to use any form of inhaler. Some elderly patients are unable to learn to use a metered dose inhaler or Turbohaler(*) despite a normal abbreviated mental test score. Studies have shown that in many people this is due to unrecognised cognitive impairment and/or dyspraxia. The executive domains of cognition are particularly important in planning and sequencing; it might be expected therefore that disordered frontal (executive) function could be a predictor of poor inhaler technique in subjects with no overt features of dementia. Objective: to explore the relationship between cognitive, and executive, function and the ability to acquire metered dose inhaler and Turbohaler technique in old age. Design: a prospective randomised observational study with blinded evaluation. Subjects: 30 inhaler-naive inpatients (21 female) with a mean age of 85 (range 75-94) and having a normal (8-10) abbreviated mental test score. Methods: subjects received standardised metered dose inhaler and Turbohaler training and were scored on an analogue scale (for metered dose inhaler) or for competence (Turbohaler) the following day. The Mini-Mental State Examination and EXIT25 (for executive function) were performed by separate observers. Results: significant correlation was found between the metered dose inhaler score and Mini-Mental State Examination (r 0.540, P<0.002) and EXIT25 (r -0.702, P<0.0001). Threshold effects emerged for the metered dose inhaler in that 18/19 with a competent score compared to 2/11 scored as incompetent had a Mini-Mental State Examination of >23 (P<0.01) and 19/19 compared to 0/11 had an EXIT25 of <15 (P<0.01). Similarly, for the Turbohaler 21/21 of the competent subjects had a Mini-Mental State Examination of >23 compared with 3/9 incompetent subjects (P<0.01), with 21/21 competent compared with 0/9 incompetent having an EXIT25 < 15 (P<0.01). Conclusion: acquisition and short-term retention of metered dose inhaler and Turbohaler techniques is unlikely to be successful in frail elderly people who have an abnormal Mini-Mental State Examination and/or EXIT25 test. The latter test, when abnormal, is probably the superior predictor of inability to learn inhaler techniques.