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Thinking, Feeling and Moving: The Effect of Mood and Cognition on the Mobility Performance of Older Adults

The following abstract was presented as part of London Health Research Day 2017.
 

Research Areas: Mental health and wellness; Mechanisms of disease
First Author: Anish Naidu
Supervisor(s): Drs. Amer Burhan, Akshya Vasudev and Manuel Montero-Odasso

Introduction:
Aging associated cognitive decline has been shown to have a negative impact on mobility, which in turn is associated with an increased risk of falls. Depression is prevalent in old age and can cause cognitive decline if untreated. However, the effect of depression on the interaction between cognition and mobility is not well understood. Dual-task gait refers to walking while performing a cognitive challenge and it is an accepted way to evaluate cognitive-mobility interaction. A larger decrease in gait velocity during dual-tasking compared to one’s baseline gait (dual-task cost) is associated with a higher risk of falls. The aim of this pilot study is to investigate the effect of depression on dual-task cost.

Hypothesis:
Depression in older adults (age 60–85) is associated with a larger dual-task cost when compared to a non-depressed control group.

Materials and Methods:
We recruited 23 community-dwelling participants (age 60–85) from London clinics who met criteria for mild-moderate major depression (Hamilton Depression Scale [HAMD-17] score of 8–22) but did not have a diagnosis of dementia. Participants were asked to complete questionnaires regarding quality of life, mood, anxiety and physical activity. They then completed a baseline gait assessment and a dual-task challenge of naming animals aloud while walking casually. Gait velocity was recorded using an electronic walkway. The change in gait velocity between baseline and dual-task was quantified using the dual-task cost percentage given by: (baseline gait velocity – dual-task gait velocity)/(baseline gait velocity). This reduced the effects of patient specific factors such as height, weight, health and physical activity on the results. For comparison, 23 healthy controls and 23 mild cognitive impairment (MCI) patients with no significant depression (Geriatric Depression Scale score below 5) were randomly selected from the databases of participants from our previous studies on gait and cognition. The three groups were matched with respect to age, gender and comorbidities. The matching and statistical analyses were performed using SPSS v23.

Results:
All three groups had a mean age between 69.0 and 69.6 years, and the mean number of comorbidities between 4.2 and 4.9. Each group had 8 males and 15 females. The mean (± SD) HAMD-17 score of the depression group was 13.5 ± 3.4. The mean (± SD) dual-task cost percentage of the healthy, depression and MCI groups were 2.4 ± 11.4%, 11.8 ± 9.9% and 22.2 ± 16.7%, respectively. One-way ANOVA showed statistically significant difference among the groups with p < 0.001. A post-hoc Tukey HSD test revealed that all three groups were statistically different from one another with p < 0.05.

Discussion and Conclusions:
Our results suggest that dual-task cost, an indicator of the risk of falls, is significantly larger in older adults with clinical depression, though to a lesser degree than in those with MCI. Although our preliminary results should be treated cautiously due to a small sample size, it is important to further assess if gait impairment caused by depression is reversible with appropriate intervention. The mechanism by which depression affects the cognition-mobility interaction needs to be clarified via larger studies with long-term follow-up. Nevertheless, our findings suggest that older adults with mild-moderate depression are at a higher risk of falls and hence fall-prevention strategies are important to consider.