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- The survey relied on by World Bank captures only symptoms
- Respondents have to be clinically diagnosed by a professional
- World Bank has since revised its brief to make this clear
“In Nigeria, chronic depression affects one in five adults,” The Guardian stated in February 2018 article.
Could long-term depression be this common?
4,581 Nigerian households interviewed
As its source, the daily directed Africa Check to a brief on the website of the World Bank’s Mind Behaviour and Development Unit. It stated: “On average, 22% of Nigerians are chronically depressed.”
The unit attributed this statistic to a nationally representative study, carried out in 2015-2016 by Nigeria’s National Bureau of Statistics. The bureau interviewed 4,581 households as part of its General Household Survey Panel, which is done every two to three years.
The survey was administered six times by visiting the same households twice every week for three weeks, the data agency’s methodology division head, Tunde Adebisi, told Africa Check.
Only household heads screened
The General Household Survey Panel included a measure of depression of the household head. For this, the survey used a version of the Center for Epidemiological Studies Depression Scale, the Mind Behaviour and Development Unit’s Julie Perng told Africa Check.
The 10-question scale is a screening test for depression and depressive disorder. But unlike the rest of the panel survey, the scale was only administered once.
Respondents were asked how many times in the past seven days they felt that everything they did was a burden and how many times their sleep was restless, for example.
The number of instances was then added up. Those who scored over 10 were “defined as those with chronic depression”, Perng said. But these people didn’t receive any follow-up diagnostic screening.
Scale just a measure of symptoms
Experts told Africa Check that while a higher score on the scale meant it was likely that a person would be depressed, multiple diagnostic interviews over time would be required to confirm this.
“It’s important to understand that the [scale] does not yield a diagnosis of depression - it’s a measure of symptoms,” Dr Ian Gotlib, chair of the department of psychology at Stanford University, told Africa Check.
“A single administration of the [scale] cannot lead to a conclusion about ‘chronic depression’ no matter what the score,” Gotlib said. “So if the researchers administered the scale only once, any statement about chronic depression based only on that measure is not warranted.”
Gotlib co-edited the Handbook of Depression with Dr Constance Hammen, who is a distinguished professor at the department of psychology and behavioural sciences at the University of California, Los Angeles.
She said the scale “certainly can be used to suggest potentially clinically significant depression if the scores are sufficiently high”. However, it “would be more appropriate from a single testing to suggest that a certain percent of Nigerian respondents experience elevated levels of depressive symptoms”.
World Bank amends brief
Following Africa Check’s query, Perng said the language in the World Bank’s public brief - referring to 22% of Nigerians - had not been “as precise” as that in their more detailed blog post.
“We will modify the brief to emphasise that we are indeed referring to household heads,” she said.
The bank has since changed it to read that “[o]ne in five Nigerian household heads have depressive symptoms”. Their blog post still refers to “chronic depression”, though.
How common is depression in Nigeria?
The true extent of depression in Nigeria is difficult to gauge, Ayodeji Ajayi, who is a clinical psychologist at the Federal Neuro-Psychiatric Hospital in Lagos, told Africa Check.
More training is needed for health personnel to diagnose depression, while hospitals should also be equipped for treatment, Ajayi said.
He further pointed out that the country’s current policy on mental health is inadequate. It dates back to 1991, while a bill first introduced in the national assembly in 2003 is yet to be passed.
Conclusion: Claim incorrect that 1-in-5 Nigerians adults are chronically depressed
One in five Nigerian adults were suffering from long-term depression, a major daily said, and that it underlies rising suicide in the country.
It attributed this statistic to the World Bank’s behavioural sciences unit. In a public brief, the unit had said the results of a depression scale had shown that “22% of Nigerians were chronically depressed”.
Experts told Africa Check that the scale does not provide a diagnosis of depression but only measures symptoms. To be certain, a mental health professional would need to make a clinical diagnosis.
The World Bank unit has since revised its brief, saying that 22% of Nigerian heads of households displayed “depressive symptoms”.