ASD Characteristics in Elderly with Mood and Anxiety Disorders

Background:  

Recently it was shown that the prevalence of autism spectrum disorders (ASDs) is 1% independent of age. However, in elderly it could well be that ASD is not yet recognized as such as when these elderly were children, specific ASD diagnoses were not broadly known. Moreover, it has been acknowledged relatively recently that ASD can be present among all possible intelligence levels. The most common earlier diagnoses for adults with ASDs who received their ASD diagnosis in adulthood were mood and anxiety disorders (Geurts & Jansen, 2011). Hence, we hypothesize that especially in elderly known with mood and anxiety disorders there will be undiagnosed cases of ASD.

Objectives:  

We investigated whether in elderly with a history of mood and anxiety disorders a larger number of these elderly would score above the clinical cut off of an autism screening instrument than elderly without such a psychiatric history.

Methods:  

The short version of the Autism Spectrum Quotient (short AQ; 28 items; self report; Hoekstra et al., 2010) was filled out by 117 healthy elderly (Controls; M=69 years, 44 males/73 females) and 259 elderly with a known history of mood and anxiety disorders (Mood; M=70 years, 83 males/167 females). A cutoff of 70 (4-point scale) was used. None of the included elderly was known with an ASD diagnosis, and all elderly took part in a large longitudinal cohort study (NESDO).

Results:  In the healthy elderly group 5.1 % had a score above the short AQ cutoff, while in the mood disordered group 30.9% scored above this cutoff. There was a significant correlation of age and AQ for the controls (r=.30), but not for those with a known history of mood disorders (r=-.10). In both groups we observed significant correlations of the AQ score with anxiety (Controls r=.41 ;Mood r=.30) and mood self-reports (Controls r=.37; Mood r=.32).

Conclusions:  As predicted, a larger proportion of elderly with a history of mood disorders showed more ASD characteristics. Moreover, an increase in the severity of the ASD characteristics was related to an increase in self-reported anxiety and mood problems. However, this does not necessarily implies that there is indeed a larger number of missed ASD cases in this sample of elderly with mood disorders, but does warrant a follow up study to determine whether the AQ can be used in such a specific group of elderly to detect previously missed cases of ASD.