July 30, 2018
The more stressors experienced in midlife, such as money problems and job pressure, the higher the risk for subsequent dementia, new research shows.
"These findings suggest that problems related to sparse resources may impact brain health over the long term and may contribute to inequalities in dementia risk," said author Paola Gilsanz, ScD, staff scientist at the Kaiser Permanente Northern California Division of Research.
The study was presented here at the Alzheimer's Association International Conference (AAIC) 2018.
Midlife Stress a Major Culprit
Dementia rates differ by race and ethnicity, Gilsanz told meeting delegates. African Americans have the highest rates, while Asian Americans have the lowest.
Reducing this inequality "is viewed as national priority," she said.
"However, the underling causes and drivers of these inequalities are unclear. And identifying them, understanding what these possible drivers are, is an important step in diminishing these racial and ethnic inequalities," she said.
"This is very valuable because it's occurring before changes in the brain are happening," she said.
Stress may be related to dementia through a number of possible pathways. These include activation of the hypothalamic-pituitary-adrenal axis, an increase in the level of glucocorticoids, hypertension and other health conditions, and health behaviors, said Gilsanz.
For this new study, the researchers used data from Kaiser Permanente Northern California, an integrated healthcare delivery system. In the 1960s and 1970s, Kaiser incorporated questionnaires into routine clinical care.
The 1972 and 1973 questionnaires asked respondents if they were experiencing serious or disturbing problems with their marriage, family, or employment or had financial problems, used drugs, or had other concerns.
The study included 12,263 persons aged 40 to 55 years at the time of the 1972 or 1973 checkup who remained a Kaiser member until 1996. The sample was 63% white, 17% African American, 8% Asian, 5% Hispanic, and 3% of other ethnic category.
From the questionnaires, researchers examined the number of stressors as well as stressor type. For the dementia outcome, they used dementia codes as captured by electronic health records.
Study participants were followed from 1996 to dementia diagnosis, death, end of Kaiser membership, or the year 2017.
Researchers adjusted for demographics, including sex, race, and education. Some models also adjusted for midlife health indicators, for example, body mass index, the presence of hypertension, smoking status, and late-life health indicators, such as stroke, heart failure, and diabetes.
Gilsanz noted that these health indicators "could be on a causal pathway between stress and dementia."
Stressors by Race
The investigators found that overall for all individual ethic/racial groups, most participants reported no stressors. "This was especially true for Asians, among whom 84% reported no stressors," said Gilsanz.
About 24% of the sample reported at least one stressor. Blacks (27%) and Hispanics (28%) were more likely to report at least one stressor compared to Asians (16%) and whites (23%).
As for the type of stressor, overall, few participants reported drug use as a problem, but about 7% reported financial stress, and 6% reported job stress.
Some stressors were more common among the different groups. For example, marital stress was reported by about 8% of blacks and Hispanics but by fewer than 3% of Asians, whereas family stressors were most often reported by Hispanics. Financial problems were more common among blacks and Hispanics than among whites or Asians.
The analysis of the relationship between stressors and dementia risk, which was adjusted for both demographics and health indicators, showed that overall, any stressor was associated with a 14% increase in dementia risk (hazard ratio, 1.14).
Compared to respondents who reported no stressor, those who reported one had a 12% increased risk for dementia; those with two stressors had a 17% increased risk. Whites and blacks accounted for much of that risk.
With respect to the type of stress, job stress (26%) and financial problems (25%) increased dementia risk the most. This was particularly true for blacks.
A limitation of the study was that some ethnic groups may be reluctant to report stress to health professionals. In addition, the researchers did not have information on duration or severity of stressors or neuroimaging data that might have lent insight into dementia diagnoses.
Following the presentation, a meeting delegate asked whether the researchers looked into stressful events in childhood, which, he said, "might be more impactful than midlife stressors."
Gilsanz responded that the data did not include information on early-life stress, "but that would be a really interesting thing to look into," she said.
Another delegate pointed out that the ability or inability to cope with stress might be as important as stress itself when it comes to dementia risk.
"I would agree," said Gilsanz. "Unfortunately, we didn't have information regarding coping mechanisms, but I do think that's important."
Addressing another query, Gilsanz said that investigating relationships within families, for example, among siblings, "is something we will definitely keep in mind."
Dr Gilsanz has disclosed no relevant financial relationships.