Investigating the relationship between comorbid headache disorders and depression

2017-02-26T23:56:27Z (GMT) by Wynd, Alexander William
Headaches and depression are comorbid at greater than chance rates, and a range of possible explanations exist to explain this. One possibility is that headaches and depression impact on each other in either a unidirectional or bidirectional manner. There is theoretical, observational, and quasi-experimental evidence indicating how headaches can and do impact on depression in certain cases and vice versa. However, it is unclear which if any direction of influence is predominant, or whether third variables, with a focus on environmental rather than biological third variables in this case, that impact on both conditions have a greater impact. The aim of this thesis is therefore to explore which of the possible non-biological contributors, if any, is predominant. The first paper attempted to test this question using three techniques. Firstly, the order of onset of headaches and depression was assessed, followed by examining for differences in headaches and depression based on order of onset, and a series of case studies were undertaken. Thirty participants were involved who had been diagnosed with headaches and depression in an earlier integrated cognitive behavioural treatment trial for both conditions. The Life History Calendar was used to establish the order of onset of headaches and depression. The results were that the order of onset was statistically equivalent, and that the headaches first group had significantly more intense headaches, suggesting that headaches may be contributing to depression in this group. In contrast, more participants believed that depression was causing or contributing to their headaches than the reverse. Also, 28 out of 30 participants believed that life events had contributed to both conditions. It was concluded that headaches may contribute to depression when intense, but that depression contributing to headaches may be more common. The first part of the second study (study 2A) involved the secondary aim of testing the ability of the Life History Calendar to improve recall of depression from five years ago, given that the Life History Calendar has been shown to improve recall of numerous other life events. Eighteen participants, who had been diagnosed with depression five years ago on average during the aforementioned treatment trial for both conditions, were asked to recall whether they were depressed or not at this time using either the Life History Calendar or the Composite International Diagnostic Interview. The results were that there was no significant difference between the two groups, with both groups having poor memory of their depression of less than 50%. It was concluded that depression from this long ago may be difficult to recall regardless of the interview method used. With regards to future research, a test of the Life History Calendar over a shorter recall period would be useful, such as the last one to two years. The second part of the second study (study 2B) expanded upon the results of study one by using a Life History Calendar with finer time units to further differentiate onset times of headaches and depression, and assessed the occurrence and timing of 17 major life events. Using the same 18 participants as in study 2A, it was surprisingly found that depression preceded and overlapped with headaches in just one out of 15 people who had experienced both conditions in the past five years. It was more common for either headaches to precede depression, both conditions to start in the same month, or the conditions to not overlap. Life events closely preceded most instances of both headaches and depression, further reinforcing the findings of study one. It was concluded that there was more evidence of headaches contributing to depression, and less evidence of the reverse, in study 2B than in study one. This may be best explained by improved depression post-treatment and by complex bidirectional influences of headaches and depression that are not fully explained by the order of onset. Finally, this final study as a secondary aim also explored long term treatment outcome five years following an integrated cognitive behaviour therapy program for headaches and depression using validated self-report questionnaires. Depression and anxiety remained significantly improved relative to pre-treatment, whereas headaches and quality of life remained unchanged. Given that headaches did improve in the entire treatment sample and from pre-treatment to post-treatment in this sample, a larger sample with greater statistical power is required to more conclusively investigate long-term headache outcome. Overall, looking at the results of all studies, it was firstly concluded that life events appear to be a critical factor. Headaches may contribute to depression when intensely painful, and although it is known that depression also likely contributes to many cases of headaches, greater research is required to more clearly identify the timing of onset when depression contributes to headaches. Weekly or even daily diaries would be ideal for this.