BJP -- eLetters for Collishaw et al., 185 (4) 350-351

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Stephan Collishaw, Barbara Maughan, and Andrew Pickles
Affective problems in adults with mild learning disability: the roles of social disadvantage and ill health
The British Journal of Psychiatry 2004; 185: 350-351 [Abstract] [Full text] [PDF]

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Affective problems in adults with mild learning disability- Confounding factors?: C Feroz-Nainar (25 February 2005)

Re: Affective problems in adults with mild learning disability- Confounding factors?: Stephan M Collishaw, Barbara Maughan, Andrew Pickles (8 April 2005)

Affective problems in adults with mild learning disability- Confounding factors? 25 February 2005

C Feroz-Nainar,
Acting Consultant in Learning Disability Psychiatry
South Birmingham PCT
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Re: Affective problems in adults with mild learning disability- Confounding factors?

doctorferoz{at}yahoo.co.uk C Feroz-Nainar

The point prevalence of a major depressive illness in people with learning disability is 2-7% which means that depression in this patient group can be twice as common as in the general population (Vee Prasher, 1999).
The study by Collishaw et al (2004) seems to show strong evidence in favour of directing strategies of primary prevention towards socio- economic deprivation and ill health in people with mild learning disabilities. However, these results should be viewed with caution as the study did not control for certain important factors. Certain groups of people with learning disability are known to be at a risk of developing a depressive illness, for example people with Down’s syndrome, Fragile X syndrome or Epilepsy (Vee Prasher, 1999). Down’s syndrome and Fragile X syndrome are among the commonest genetic causes of learning disabilities and epilepsy is 10 times more common in people with mild learning disability compared with the general population (Oliver Russell, 1997).
This may imply that the socio-economic deprivation could have well been a confounding factor as the above 3 at-risk groups may have had a depressed mood irrespective of the social factors.
References:
1. Stephan Collishaw, Barbara Maughan, and Andrew Pickles 'Affective problems in adults with mild learning disability: the roles of social disadvantage and ill health' Br J Psychiatry 2004; 185: 350-351
2. Oliver Russell 'The Psychiatry of Learning Disabilities', College Seminar Series, Gaskell, 1997, The Royal College of Psychiatrists
3. Vee Prasher 'Presentation and management of depression in people with learning disability', Advances in Psychiatric Treatment, 1999, 5: 447 -54

Re: Affective problems in adults with mild learning disability- Confounding factors? 8 April 2005

Stephan M Collishaw,
Lecturer
Institute of Psychiatry, King's College London,
Barbara Maughan, Andrew Pickles
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Re: Re: Affective problems in adults with mild learning disability- Confounding factors?

s.collishaw{at}iop.kcl.ac.uk Stephan M Collishaw, et al.

Collishaw, Maughan and Pickles (2004) tested the extent to which adult social adversity and ill health contributed to an elevated risk for depressed mood among adults with mild learning disability (MLD). The study used data from the 1958 National Child Development Study (NCDS), a nationally representative cohort followed from birth to age 43.
Dr. Feroz-Nainar makes the point that epilepsy, Fragile X, and Down's syndrome are among the biological/genetic causes and correlates of learning disabilities (BJP e-letter published 25 February 2005), and raises the question whether these factors could have contributed to the higher rate of depressed affect associated with MLD.
A previous report on the NCDS birth cohort confirms that epilepsy and other neurological abnormalities were indeed more common for individuals with mild learning disabilities (MLD) than for non-learning disabled controls included in our studies. However, the majority of individuals with MLD had no known neuro-epileptic abnormalities and mild learning disability was more commonly associated with childhood social and family adversity (Maughan et al., 1999).
To test the possibility that MLD/non-MLD group differences in depressed affect were due to biological factors such as epilepsy, we re- analysed the statistical models reported in our recent paper (Collishaw et al., 2004). Controls for childhood epilepsy/neurological problems did not reduce group differences in adult depressed affect (model adjusted only for gender: OR = 2.84 [1.7-4.9], p < .001; model adjusted for gender and childhood neurological problems/epilepsy: OR = 2.79 [1.6-4.8], p < .001). This stands in contrast to the partial mediating effect of controlling for childhood social adversity (Maughan et al., 1999; Collishaw et al., 2004) and the almost complete mediating effect of additional controls for adult ill health and adult social adversity (Collishaw et al., 2004).
We cannot of course rule out completely the possibility that some other unmeasured third factor is confounded with social adversity and could explain our findings. We also acknowledge that specific biological factors may be of particular importance for understanding affective problems in some individuals with MLD. Nevertheless, when assessed in an unselected general population cohort such as the NCDS, social factors and adult health do appear to play an important role in contributing to depressed mood among people with mild learning disability.
Declaration of interest: none
References: Collishaw S., Maughan B., Pickles A. (2004). Affective problems in adults with mild learning disability: the roles of social disadvantage and ill health. British Journal of Psychiatry, 185 (4), 350-351. Feroz-Nainar, C. (2005). Affective problems in adults with mild learning disability - confounding factors? British Journal of Psychiatry, electronic letter published 25 February 2005. Maughan B., Collishaw S., Pickles A. (1999). Mild mental retardation: Psychosocial functioning in adulthood. Psychological Medicine, 29, 351- 366.