Depression Through the Generations
Hi and welcome to “This Week in Parenting Research”! This is a bimonthly column where I attempt to find new research that may be of interest to parents/those raising kids.
This week I saw a rather interesting headline “Is depression in parents, grandparents linked to grandchildren’s depression?” and decided to check out the study behind it. I was fully expecting it would be some sort of questionnaire, study, but what I actually found was a lot more interesting. It’s actually a four generation study that’s been operating out of Yale (in New Haven, CT) for over 30 years.
The history: You can read the full history of the project here and here, but basically it was started in 1982 studying parents who had been diagnosed with and were being treated for major depression. The researchers then also recruited families from the same town who had no history of depression to use as a control. The data has been collected in waves, approximately every ten years: 1982-1986, 1992-1994, 1999-2002, and 2002-2007. Each wave has enrolled subsequent children of the families, and we are now up to the great-grandchildren of the original participants.
The goal: The goal is to understand how depression can potentially run through families. This study is one of the only longitudinal multigenerational study on depression currently being run. In addition to providing baseline information on risk, one of the goals of the study is to help researchers identify possible biomarkers for depression. Basically if you have 3 generations of very depressed people, the chances that you’ll be able to find a gene or other biomarker they have in common that may be driving the depression is higher. Additionally, if you can identify family risk, you can hopefully help catch high risk kids earlier on.
The caveats: Of course there are always caveats. Because of the labor intensive nature of this study, the sample size is relatively small: 91 families. The exact number of people in each cohort has changed since offspring are included. All of the originally selected participant were Caucasian, and all living in the area around Yale in New Haven, CT. The depressed patients were recruited from an outpatient clinic and had all been diagnosed with moderate to severe unipolar depression. Again, this was in 1982, so selection was all based on criteria used at that time. Given that psychiatric help was less available at the time and many mental health issues less recognized, this population may be different from what we think of today. All of these things can limit the generalizability of the results.
The methods: As each wave of data collection occurs, the researchers call up the subjects and have them come in for a full psychological assessment including EEGs and MRIs. The actual people doing the assessments are blinded to family history of the person they are assessing. This set up means they catch even people whose depression wasn’t diagnosed, and also helps eliminate researcher bias.
The results: One of the coolest things about this project is that the make all of their publications freely available here. The most recent one wasn’t posted yet, so I took a look at one from earlier this year that tracked major depression risk over the lifespan. This was a cool study because of the sheer length of time it looked at people. Overall, the found that children of depressed parents had much higher rates of major depression (74% vs 34%) and anxiety (72% vs 48%), but were not more likely to have a substance abuse problem, be bipolar, have dysthymic disorder or have other mental health problems. Overall the chances of having any mental health problem at any point in life was actually pretty high: 93% for the children of depressed parents and 77% for the children of non-depressed parents. This difference did not reach statistical significance (p=.06). One of the more interesting charts was the “age of onset” charts for major depression:And this one for anxiety:
Conclusions: It’s interesting to see how major depression and anxiety travel through families. With new methods of treatment available since the early 80s, it will be interesting to see how these patterns change (or not) going forward. It was interesting to note that the rates of major depression and anxiety were much higher in this study in both the study and the control group than normal estimates of the general population suggest. That may be due to the increased psychiatric screening, or it may show that these groups were not random. While the study is small and hard to generalize, it is incredibly valuable to track mental health over the entire life span. Hopefully as this research continues we will be able to improve our ability to assess risk and subsequently improve our ability to intervene early.
Featured image credit: Dominika Komender