There appears to be a link between depression/anxiety/PTSD and dementia, although the evidence is incomplete and the reason is unclear. Mental illness may cause dementia or may be prodromal or comorbid with dementia, or dementia may trigger a relapse of symptoms in individuals with a history of mental illness. This study examined the link between depression/anxiety/PTSD and dementia by evaluating the prevalence of these disorders in people with dementia, relative to their healthy peers. Existing meta-analyses have examined the prevalence of clinically-significant depression and anxiety in Alzheimer’s disease (AD), and depression in frontotemporal dementia (FTD), but have not considered vascular dementia (VaD), dementia with Lewy bodies (DLB), PTSD, or anxiety in FTD. The current meta-analysis compared the prevalence of clinically-significant depression, anxiety and PTSD in the four most common types of dementia (AD, VaD, DLB, FTD) and in unspecified dementia to that of healthy controls (PROSPERO number: CRD42017082086). PubMed, EMBASE, PsycINFO and CINAHL database searches identified 120 eligible studies. Prevalence rates were calculated for depression and anxiety in AD, VaD, DLB, FTD, unspecified dementia, and controls. PTSD data were only available for unspecified dementia. Subgroup analyses indicated that depression, but not anxiety, was more prevalent in people with dementia compared to controls; however, the anxiety analyses were probably under-powered. The results support a link between depression and dementia; however, the link between anxiety or PTSD and dementia remains unclear due to insufficient data. Longitudinal data is now needed to clarify whether depression/anxiety/PTSD may be risk factors for dementia.

中文翻译：

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痴呆症患者的抑郁，焦虑和PTSD患病率：系统评价和荟萃分析

抑郁/焦虑/ PTSD与痴呆之间似乎存在联系，尽管证据不完整且原因尚不清楚。精神疾病可能会导致痴呆症，或者可能是痴呆症的前驱症或合并症，或者痴呆症可能会导致具有精神病史的人复发症状。这项研究通过评估痴呆症患者相对于健康同伴的患病率，研究了抑郁症/焦虑症/ PTSD与痴呆症之间的联系。现有的荟萃分析检查了阿尔茨海默氏病（AD）和额颞叶痴呆（FTD）的临床上重要的抑郁症和焦虑症的患病率，但尚未考虑血管性痴呆（VaD），路易体痴呆（DLB），PTSD或FTD中的焦虑症。当前的荟萃分析比较了四种最常见类型的痴呆（AD，VaD，DLB，FTD）和未明确的痴呆与健康对照者的临床上显着的抑郁症，焦虑症和PTSD的发生率（PROSPERO编号：CRD42017082086）。PubMed，EMBASE，PsycINFO和CINAHL数据库搜索确定了120项合格研究。计算AD，VaD，DLB，FTD，未指明的痴呆症和对照中抑郁症和焦虑症的患病率。PTSD数据仅适用于未指定的痴呆症。亚组分析表明，与对照组相比，痴呆症患者的抑郁症而非焦虑症更为普遍。然而，焦虑分析的动力不足。结果支持抑郁症和痴呆症之间的联系；然而，由于数据不足，焦虑或PTSD与痴呆之间的联系仍不清楚。现在需要纵向数据来阐明抑郁症/焦虑症/ PTSD是否可能是痴呆症的危险因素。