1. Association of Body Mass Index (BMI) and Depression Severity
Poster Number: NR7-40
Association of Body Mass Index (BMI) and Depression Severity
in Late Life Depression
Alana Kivowitz*, BA, Derek Pisner*, BA, Ross Crothers, BA, Katie Tegenkamp, BS, David Bickford, BA,
J. Craig Nelson, MD, & R. Scott Mackin, PhD
Late Life Depression Program
We gratefully acknowledge grant support for this study: NIMH K08 MH , UCSF Leon Epstein Fund, the ADNI-Depression Project
Figure 1a & 1b: Association of BMI and Depression Severity
OBJECTIVE:
This study was conducted to evaluate the association between Body Mass Index (BMI) and depression severity in Late Life Depression (LLD). We hypothesize that when compared to age and education matched patients, LLD individuals with a high BMI will rate higher on clinical scales of depression severity than LLD individuals within the normal BMI range.
BACKGROUND:
Major Depressive Disorder (MDD) is a significant psychiatric illness, and up to 15% of adults over the age of 65 suffer from Late Life Depression (LLD). Previous research has found a positive relationship between BMI and depression severity in young adult populations (1) , however research on this topic within the geriatric population has been limited.
Further, studies which have looked at this association in older adults commonly used the Geriatric Depression Scale (GDS), which is a self-reported measure of depression severity (2). These studies have also explored physical activity and diabetic status as important factors. While some of the findings have shown an inverse linear relationship between BMI and depression in older adult men (3), no studies to our knowledge have used a clinician rating of depression, such as the Hamilton Depression Rating Scale (HDRS). The purpose of this study was to therefore examine the association between BMI and depression severity using a clinical measure of depression (HDRS), and to compare findings when using a subjective measure (GDS).
METHODS:
Eligibility: Eligibility criteria included older adults (> 65 years of age) with a SCID diagnosis of Major Depressive Disorder (MDD), a score of 19 or greater on the HDRS, and not having dementia (MMSE > 24).
Assessment of Depression and Body Mass Index:
Depression was evaluated by licensed psychologists using the Structured Clinical Interview for the Diagnoses of DSM-IV Disorders (SCID) and criteria from the Diagnostic and Statistical Manual, 4th edition (DSM-IV). Depression Severity was assessed using the clinician administered 24-item Hamilton Depression Rating Scale (HDRS), and the 15-item Geriatric Depression Scale (GDS) as a self report measure.
BMI was calculated through self-reported weight and height information. Participants in the sample were divided into two groups, based on the following BMI thresholds: those having a BMI equal to or above 25 were defined as “high BMI” and those having a BMI less than 25 were defined as “normal BMI.” These groupings are based on obesity standards set by the World Health Organization (WHO).
Information on diabetic status and quantity of daily exercise was also collected.
DATA ANALYTIC PROCEDURE:
Analyses of Covariance (ANCOVA) were used to compare depression severity between groups, controlling for age and education, in addition to physical activity and diabetic status.
RESULTS:
Participants included 71 individuals enrolled in an ongoing study on LLD. Thirty-two participants were categorized as “normal BMI” (45%) and 39 as “high BMI” (55%). There were no statistical differences in age, education, or gender between groups (Table 1). Covariates in the analyses (age, education, diabetic status, and physical activity) were not significant.
BMI was not significantly associated with depression severity as measured by the HDRS, F(5,67) = 0.415, p = BMI was significantly associated, however, with self-reported depression severity on the GDS, F(5,61) = 6.756, p = Specifically, increased BMI is associated with lower self-reported depression severity (Table 2, Figures 1a & 1b).
DISCUSSION:
Despite evidence that would suggest a meaningful relationship between BMI and depression severity, the present study revealed no such association based on the standard HDRS measure of depression. This finding diverges from the common assumption that a positive linear relationship exists between BMI and depression. On the other hand, our findings did reveal that the “normal BMI” group reported more severe depressive symptoms than did the “high BMI” group on a self-reported measure (GDS). These findings suggest that other biological or sociocultural mechanisms may contribute to this phenomenon, perhaps that individuals within the normal BMI group are more self-conscious and sensitive to societal stigmas, and in turn report higher depression severity on the GDS.
One point of interest is the contrast between the two measures of depression severity. While the present findings suggest that an individual’s BMI classification may contribute to their self-perceived depression without a similar objective diagnostic rating, these findings are interpreted with caution. Though significant, the difference between mean scores on the GDS is small. Further, a selection bias may confound the results due to a reduced variation in scores, as our sample only included MDD patients with a HDRS of 19 or greater. Finally, self-reported data, such as height and weight information, may not be a reliable measure of BMI.
Further research is warranted to investigate the difference between perception of depression relative to clinician ratings of depression. Future research should also be conducted to clarify the precise mechanisms of association between BMI and depression severity.
CONCLUSION:
Contrary to the popular assumptions and stigmas surrounding high BMI and mental health, our findings suggest that higher BMI is significantly associated with lower self-perceived depression severity. The HDRS measure of clinical depression severity was not significantly associated with BMI in this sample.
Table 1: Demographic Characteristics
“Normal BMI”
“High BMI” n
Mean (sd) F p
Age 31
72.0 (5.7) 39
71.8 (6.6)
0.02 
0.904
Education 32
16.2 (2.4)
15.7 (2.8)
 0.54
0.462
BMI
32 
22.1 (2.0)
29.9 (4.5) % F  p 
Diabetic Status
(Diabetic)
9.4
23.1
2.36 
0.129
Daily Exercise
(Less than 30 minutes)
37.5
56.4
 2.53
0.116 χ2
Gender
(Female)
78.1
74.4
0.14
0.780
Table 2: Adjusted Means of Depression Severity between Groups
Normal BMI
High BMI n
Mean (sd) F p
HDRS 32
22.7 (5.0) 37
24.1 (4.9)
0.415
0.522
GDS 28
10.3 (2.1) 35
8.6 (2.7)
6.756
0.012
HDRS = Hamilton Depression Rating Scale, GDS = Geriatric Depression Scale, BMI = Body Mass Index
REFERENCES:
1. Hoare, E., et al. (2014). Journal of Epidemiology & Community Health.
2. Luppino, F.S., et al. (2010). Archives of General Psychiatry;
3. Dong, Q., et al. (2012). International Journal of Geriatric Psychiatry