Table 1.
Study characteristics
| Study type and setting, location | Follow-up/look-back period, years (SD) | Mean age, years (SD) | Female, n (%) | Education level, n (%) | Dropout rate/response rate percentage | Baseline cognition measure | Anxiety measure; cut-off | Baseline anxiety, n (%) | Controls for depression; baseline depression measure | Dementia diagnosis; criteria (no of cases); OR/HR (95% CI) | |
| Boot et al19 (N=441) | Population-based matched case-controlled, Mayo Clinic Rochester, Minnesota, USA | Lifelong diagnoses documented by medical record | 72.5 (7.3) —DLB cases age at diagnosis | 103 (23.1) | >9 years education; (95) | NR | NR | Clinical diagnosis, present in medical history section of medical record | 23 (27) cases; 14 (5) controls |
Yes; clinical diagnosis from medical history record | DLB diagnosis by behavioural neurologist; published criteria by McKeith et al25 (n=147); OR 7.4 (3.5 to 16) |
| Gallacher et al20 (N=1160) |
Prospective, community-based cohort; Caerphilly, Wales, UK | Mean follow-up period; 17.3 (1.3) | 56.1 (4.4)—mean age at inclusion | 0 | No qualifications; 601 (55) | 20 | NR; dementia unlikely at inclusion (mean age <60 years) | STAI; score of ≥35 | 585 (50) | Yes; GHQ-30 | Dementia diagnosis; DSM-IV or medical records (n=90); OR 1.62 (0.59 to 4.41) |
| Petkus et al21 (N=1082) | Prospective, community based cohort; Swedish twins drawn from Swedish Twin Registry, Sweden | Follow-up period; 28 (0) | 60.86 (11.15)—mean age at inclusion | 612 (56.6) | Beyond elementary education; 423 (39) |
29.8 | MMSE | State anxiety subscale of STPI; STPI>1 SD Q1-Q4 (assessments over four time points) |
403 (37) | Yes; OARS Depression Subscale, CES-D | Dementia diagnosis; DSM-III or DMS-IV (n=172); HR 1.48 (1.01 to 2.18) |
| Zilkens et al18 (N=27 136) |
Population-based matched case-controlled, Western Australia | Mean look-back period; cases 20.4 (10.4), controls 20.0 (10.3) | 78.7 (4.7)—mean age at final time point | 15 359 (56.6) | NR | 6.17 (excluded individuals) |
NR | Clinical diagnosis using ICD-10 AM (Australian Modification) codes documented in health records; meeting diagnostic threshold | 379 (2.8) cases | Yes; clinical diagnosis by GP | Dementia diagnosis; ICD-10 (n=13 568); OR 1.61 (1.28 to 2.02) (>10 years look-back period) |
CES-D, Centre of Epidemiological Studies Depression Subscale; DLB, Dementia with Lewy bodies; DSM III/IV, Diagnostic and Statistical Manual of Mental Disorders III/IV; GHQ-30, 30-item General Health Questionnaire; GP, general practitioner; ICD-10, International Classification of Diseases, 10th Revision; MMSE, Mini-Mental State Examination; NR, not recorded; OARS, older American resources and services; STAI, State Trait Anxiety Inventory; STPI, State Trait Personality Inventory.