Understanding the Impact of Brain Disorders: Towards a 'Horizontal Epidemiology' of Psychosocial Difficulties and Their Determinants.
OBJECTIVE
To test the hypothesis of 'horizontal epidemiology', i.e. that psychosocial difficulties (PSDs), such as sleep disturbances, emotional instability and difficulties in personal interactions, and their environmental determinants are experienced in common across neurological and psychiatric disorders, together called brain disorders.


METHODS
A multi-method study involving systematic literature reviews, content analysis of patient-reported outcomes and outcome instruments, clinical input and a qualitative study was carried out to generate a pool of PSD and environmental determinants relevant for nine different brain disorders, namely epilepsy, migraine, multiple sclerosis, Parkinson's disease, stroke, dementia, depression, schizophrenia and substance dependency. Information from these sources was harmonized and compiled, and after feedback from external experts, a data collection protocol including PSD and determinants common across these nine disorders was developed. This protocol was implemented as an interview in a cross-sectional study including a convenience sample of persons with one of the nine brain disorders. PSDs endorsed by at least 25% of patients with a brain disorder were considered associated with the disorder. PSD were considered common across disorders if associated to 5 out of the 9 brain disorders and if among the 5 both neurological and psychiatric conditions were represented.


METHODS
The data collection protocol with 64 PSDs and 20 determinants was used to collect data from a convenience sample of 722 persons in four specialized health care facilities in Europe.


RESULTS
57 of the PSDs and 16 of the determinants included in the protocol were found to be experienced across brain disorders.


CONCLUSIONS
This is the first evidence that supports the hypothesis of horizontal epidemiology in brain disorders. This result challenges the brain disorder-specific or vertical approach in which clinical and epidemiological research about psychosocial difficulties experienced in daily life is commonly carried in neurology and psychiatry and the way in which the corresponding health care delivery is practiced in many countries of the world.
Faculty of Social and Human Sciences, School of Psychology, University of Southampton, Southampton, United Kingdom; Department of Medical Informatics, Biometry and Epidemiology (IBE), Chair for Public Health and Health Services Research, Research Unit for Biopsychosocial Health, Ludwig-Maximilians-University (LMU), Munich, Germany; Swiss Paraplegic Research, Nottwil, Switzerland.
Alarcos
A
Cieza
Department of Psychiatry, Institute of Psychiatry and Neurology, Warsaw, Poland.
Marta
M
Anczewska
Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Department of Psychiatry, Universidad Autónoma de Madrid, Psychiatry Service, Instituto de Investigación del Hospital Universitario de La Princesa (IIS-IP), Madrid, Spain.
Jose Luis
JL
Ayuso-Mateos
European Brain Council, Brussels, Belgium.
Mary
M
Baker
Swiss Paraplegic Research, Nottwil, Switzerland.
Jerome
J
Bickenbach
Multi-Country Studies, Department of Measurement and Health Information Systems, World Health Organization, Geneva, Switzerland.
Somnath
S
Chatterji
Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, United Kingdom; Faculty of Health Sciences, University of Sydney, Sydney, New South Wales, Australia; The London School of Hygiene and Tropical Medicine, London, United Kingdom.
Sally
S
Hartley
Neurology, Public Health and Disability Unit, Scientific Directorate, Neurological Institute Carlo Besta IRCCS Foundation, Milan, Italy.
Matilde
M
Leonardi
A-Clinic Foundation, Helsinki, Finland.
Tuuli
T
Pitkänen
D000328:Adult; D000342:Affective Symptoms / Q000453:epidemiology / Q000209:etiology; D000368:Aged; D000369:Aged, 80 and over; D001294:Attitude to Health; D001927:Brain Diseases / Q000150:complications* / Q000453:epidemiology / Q000523:psychology; D017281:Cost of Illness; D003625:Data Collection; D005060:Europe; D005260:Female; D017144:Focus Groups; D006801:Humans; D007398:Interpersonal Relations; D007406:Interview, Psychological; D008297:Male; D001523:Mental Disorders / Q000150:complications* / Q000453:epidemiology / Q000523:psychology; D008875:Middle Aged; D008960:Models, Psychological; D062072:Patient Acuity; D063868:Patient Outcome Assessment; D010361:Patients / Q000523:psychology; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000209:etiology; D012931:Social Environment; D057545:Social Stigma; D012944:Social Support