Objective is to explore how multimorbidity is defined in the scientific literature, with a focus on the roles of diseases, risk factors, and symptoms in the definitions. Design: Systematic review. Methods: MEDLINE (PubMed), Embase, and The Cochrane Library were searched for relevant publications up until October 2013. One author extracted the information. Ambiguities were resolved, and consensus reached with one co-author. Outcome measures were: cut-off point for the number of conditions included in the definitions of multimorbidity; setting; data sources; number, kind, duration, and severity of diagnoses, risk factors, and symptoms. We reviewed 163 articles. In 61 articles (37%), the cut-off point for multimorbidity was two or more conditions (diseases, risk factors, or symptoms). The most frequently used setting was the general population (68 articles, 42%), and primary care (41 articles, 25%). Sources of data were primarily self-reports (56 articles, 42%). Out of the 163 articles selected, 115 had individually constructed multimorbidity definitions, and in these articles diseases occurred in all definitions, with diabetes as the most frequent. Risk factors occurred in 98 (85%) and symptoms in 71 (62%) of the definitions. The severity of conditions was used in 26 (23%) of the definitions, but in different ways. The definition of multimorbidity is heterogeneous and risk factors are more often included than symptoms. The severity of conditions is seldom included. Since the number of people living with multimorbidity is increasing there is a need to develop a concept of multimorbidity that is more useful in daily clinical work. Key pointsThe increasing number of multimorbidity patients challenges the healthcare system. The concept of multimorbidity needs further discussion in order to be implemented in daily clinical practice.Many definitions of multimorbidity exist and most often a cut-off point of two or more is applied to a range of 4–147 different conditions.Diseases are included in all definitions of multimorbidity.Risk factors are often included in existing definitions, whereas symptoms and the severity of the conditions are less frequently included.

IMPORTANCE Although depression and type 2 diabetes mellitus (DM) may independently increase the risk for dementia, no studies have examined whether the risk for dementia among people with comorbid depression and DM is higher than the sum of each exposure individually.OBJECTIVE To examine the risk for all-cause dementia among persons with depression, DM, or both compared with persons with neither exposure. DESIGN, SETTING, AND PARTICIPANTSWe performed a national population-based cohort study of 2 454 532 adults, including 477 133 (19.4%) with depression, 223 174 (9.1%) with DM, and 95 691 (3.9%) with both. We included all living Danish citizens 50 years or older who were free of dementia from January 1, 2007, through December 31, 2013 (followed up through December 31, 2013). Dementia was ascertained by physician diagnosis from the Danish National Patient Register or the Danish Psychiatric Central Register and/or by prescription of a cholinesterase inhibitor or memantine hydrochloride from the Danish National Prescription Registry. Depression was ascertained by psychiatrist diagnosis from the Danish Psychiatric Central Research Register or by prescription of an antidepressant from the Danish National Prescription Registry. Diabetes mellitus was identified using the National Diabetes Register. MAIN OUTCOMES AND MEASURESWe estimated the risk for all-cause dementia associated with DM, depression, or both using Cox proportional hazards regression models that adjusted for potential confounding factors (eg, demographics) and potential intermediates (eg, medical comorbidities).RESULTS During 13 834 645 person-years of follow-up, 59 663 participants (2.4%) developed dementia; of these, 6466 (10.8%) had DM, 15 729 (26.4%) had depression, and 4022 (6.7%) had both. The adjusted hazard ratio for developing all-cause dementia was 1.83 (95% CI, 1.80-1.87) for persons with depression, 1.20 (95% CI, 1.17-1.23) for persons with DM, and 2.17 (95% CI, 2.10-2.24) for those with both compared with persons who had neither exposure. The excess risk for all-cause dementia observed for individuals with comorbid depression and DM surpassed the summed risk associated with each exposure individually, especially for persons younger than 65 years (hazard ratio, 4.84 [95% CI,). The corresponding attributable proportion due to the interaction of comorbid depression and DM was 0.25 (95% CI, 0.13-0.36; P < .001) for those younger than 65 years and 0.06 (95% CI, 0.02-0.10; P = .001) for those 65 years or older.CONCLUSIONS AND RELEVANCE Depression and DM were independently associated with a greater risk for dementia, and the combined association of both exposures with the risk for all-cause dementia was stronger than the additive association.

Objective To assess the efficacy at 12 months of an early psychosocial counselling and support programme for outpatients with mild Alzheimer's disease and their primary care givers.Design Multicentre, randomised, controlled, rater blinded trial. Setting Primary care and memory clinics in five Danish districts.Participants 330 outpatients with mild Alzheimer's disease and their 330 primary care givers.Interventions Participating dyads (patient and primary care giver) were randomised to control support during follow-up or to control support plus DAISY intervention (multifaceted and semi-tailored counselling, education, and support).Main outcome measures Primary outcomes at 12 months for patients were change from baseline in mini mental state examination (MMSE) score, Cornell depression scale score, and proxy rated European quality of life visual analogue scale (EQ-VAS) score. For care givers, outcomes were change from baseline in geriatric depression scale (GDS 30 items) score and EQ-VAS score.Results Because of multiple testing, statistical significance was set at an adjusted P limit of <0.0005. At 12 months there were no significant differences between the two allocation groups in changes from baseline in the primary and secondary outcomes. However, although non-significant with the adjusted P limit, a small difference was observed for one of the primary patient outcomes (Cornell depression scale score) in patients in favour of the DAISY intervention group before and after adjusting for attrition (P=0.0146 and P=0.0103 respectively). ConclusionsThe multifaceted, semi-tailored intervention with counselling, education, and support for patients with mild Alzheimer's disease and their care givers did not have any significant effect beyond that with well structured follow-up support at 12 months after adjustment for multiple comparisons. The small positive effect found in the unadjusted primary outcome addressing depressive symptoms in patients may call for further research focusing on patients with Alzheimer's disease and comorbid depression. Trial registration ISRCTN74848736. IntroductionAlzheimer's disease is a common neurodegenerative disease characterised by progressive decline in cognitive, social, and occupational function, and often associated with affective symptoms and behavioural disturbances. 1 Alzheimer's disease accounts for 60-80% of all cases of dementia, and recent figures indicate that as many as 35 million people worldwide have dementia, which is projected to increase to 65 million within the next two decades. 2 Most patients with Alzheimer's disease reside in the community and require assistance and supervision from care givers. BeingCorrespondence to: F B Waldorff fransw@sund.ku.dk Extra material supplied by the author. Effect of the intervention compared with control (intention-to-treat analysis) on the primary and secondary outcomes and the difference of these outcomes from baseline, with outcomes reported as medians with interquartile ranges (see http://www.bmj.com/content/345/bmj.e469...