Objective Huntington's Disease (HD) is an inherited progressive neurodegenerative disorder, characterised by a triad of motor, cognitive and psychiatric symptoms. Depression is common in patients with HD, but does not correlate well with motor or cognitive measures of disease progression, suggesting that different neuropathological process may be involved. However clinical experience suggests that depressive symptoms in HD are variable and tend to fluctuate from day to day and in response to environmental factors and mental stimulation, suggesting that HD related cognitive changes and impaired motivation might contribute to the aetiology of depressive symptoms. The aim of the present exploratory pilot study was therefore to compare the clinical features of depression in HD with depression in general population.
Method A cross sectional comparison study was completed with 15 depressed Huntington's Disease patients and 15 depressed patients from general population. Recruitment of the participants was based on specific inclusion and exclusion criteria and selected patients with moderate depression. The comparison group was matched for age, sex and Visual Analogue Mood Scores. All subjects in both groups completed the Hospital Anxiety and Depression Scale, Beck Depression Inventory, Test for Anhedonia questionnaire and Montgomery Asberg Depression Rating Scale; the latter was modified for this study with 3 extra questions about environmental susceptibility of low mood.
Results The results of the study indicate that there was no significant difference between groups in the clinical features of depression, based on the total score of all the questionnaires used. Depressed patients without HD had significantly higher scorers on the lack of enjoyment (anhedonia) item from the Hospital Anxiety and Depression Scale; however, this was the only significant difference between the groups, and this finding did not survive Bonferroni Correction. There was a trend for concentration difficulties and improvement in mood based on changes in environmental factors to be more pronounced in HD patients, but this difference was not statistically significant based on p values and confidence intervals.
Conclusion We conclude that there is no significant difference in the clinical features of depression in Huntington's disease compared to depressed patients from general population. The overall effect size for the whole study was low to medium and based on the calculations more significant results could be obtained with more than 100 participants in each group in future studies. We plan a further study looking at the pervasiveness of low mood over time in the two groups.